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$ unbound -c /etc/unbound/unbound.confNINDENT NINDENT Most settings are the defaults. Stop the server with: NDENT 0.0 NDENT 3.5
$ kill \(gacat /etc/unbound/unbound.pid\(gaNINDENT NINDENT Below is a minimal config file. The source distribution contains an extensive example.conf file with all the options. NDENT 0.0 NDENT 3.5
# unbound.conf(5) config file for unbound(8). server: directory: \(dq/etc/unbound\(dq username: unbound # make sure unbound can access entropy from inside the chroot. # e.g. on linux the use these commands (on BSD, devfs(8) is used): # mount --bind -n /dev/urandom /etc/unbound/dev/urandom # and mount --bind -n /dev/log /etc/unbound/dev/log chroot: \(dq/etc/unbound\(dq # logfile: \(dq/etc/unbound/unbound.log\(dq #uncomment to use logfile. pidfile: \(dq/etc/unbound/unbound.pid\(dq # verbosity: 1 # uncomment and increase to get more logging. # listen on all interfaces, answer queries from the local subnet. interface: 0.0.0.0 interface: ::0 access-control: 10.0.0.0/8 allow access-control: 2001:DB8::/64 allowNINDENT NINDENT
verbosity: <number> The verbosity level. NDENT 7.0
Level 0 No verbosity, only errors.
Level 1 Gives operational information.
Level 2 Gives detailed operational information including short information per query.
Level 3 Gives query level information, output per query.
Level 4 Gives algorithm level information.
Level 5 Logs client identification for cache misses. NINDENT The verbosity can also be increased from the command line and during run time via remote control. See \%unbound(8) and \%unbound-control(8) respectively. Default: 1 NINDENT NDENT 0.0
statistics-interval: <seconds> The number of seconds between printing statistics to the log for every thread. Disable with value 0 or \(dq\(dq. The histogram statistics are only printed if replies were sent during the statistics interval, requestlist statistics are printed for every interval (but can be 0). This is because the median calculation requires data to be present. Default: 0 (disabled) NINDENT NDENT 0.0
statistics-cumulative: <yes or no> If enabled, statistics are cumulative since starting Unbound, without clearing the statistics counters after logging the statistics. Default: no NINDENT NDENT 0.0
extended-statistics: <yes or no> If enabled, extended statistics are printed from \%unbound-control(8). The counters are listed in \%unbound-control(8). Keeping track of more statistics takes time. Default: no NINDENT NDENT 0.0
statistics-inhibit-zero: <yes or no> If enabled, selected extended statistics with a value of 0 are inhibited from printing with \%unbound-control(8). These are query types, query classes, query opcodes, answer rcodes (except NOERROR, FORMERR, SERVFAIL, NXDOMAIN, NOTIMPL, REFUSED) and PRZ actions. Default: yes NINDENT NDENT 0.0
num-threads: <number> The number of threads to create to serve clients. Use 1 for no threading. Default: 1 NINDENT NDENT 0.0
port: <port number> The port number on which the server responds to queries. Default: 53 NINDENT NDENT 0.0
interface: <IP address or interface name[@port]> Interface to use to connect to the network. This interface is listened to for queries from clients, and answers to clients are given from it. Can be given multiple times to work on several interfaces. If none are given the default is to listen on localhost. If an interface name is used instead of an IP address, the list of IP addresses on that interface are used. The interfaces are not changed on a reload (kill -HUP) but only on restart. A port number can be specified with @port (without spaces between interface and port number), if not specified the default port (from \%port) is used. NINDENT NDENT 0.0
ip-address: <IP address or interface name[@port]> Same as \%interface (for ease of compatibility with \%nsd.conf(5)). NINDENT NDENT 0.0
interface-automatic: <yes or no> Listen on all addresses on all (current and future) interfaces, detect the source interface on UDP queries and copy them to replies. This is a lot like \%ip-transparent, but this option services all interfaces whilst with \%ip-transparent you can select which (future) interfaces Unbound provides service on. This feature is experimental, and needs support in your OS for particular socket options. Default: no NINDENT NDENT 0.0
interface-automatic-ports: \(dq<string>\(dq List the port numbers that \%interface-automatic listens on. If empty, the default port is listened on. The port numbers are separated by spaces in the string. This can be used to have interface automatic to deal with the interface, and listen on the normal port number, by including it in the list, and also HTTPS or DNS-over-TLS port numbers by putting them in the list as well. Default: \(dq\(dq NINDENT NDENT 0.0
outgoing-interface: <IPv4/IPv6 address or IPv6 netblock> Interface to use to connect to the network. This interface is used to send queries to authoritative servers and receive their replies. Can be given multiple times to work on several interfaces. If none are given the default (all) is used. You can specify the same interfaces in \%interface and \%outgoing-interface lines, the interfaces are then used for both purposes. Outgoing queries are sent via a random outgoing interface to counter spoofing. If an IPv6 netblock is specified instead of an individual IPv6 address, outgoing UDP queries will use a randomised source address taken from the netblock to counter spoofing. Requires the IPv6 netblock to be routed to the host running Unbound, and requires OS support for unprivileged non-local binds (currently only supported on Linux). Several netblocks may be specified with multiple \%outgoing-interface options, but do not specify both an individual IPv6 address and an IPv6 netblock, or the randomisation will be compromised. Consider combining with \%prefer-ip6: yes to increase the likelihood of IPv6 nameservers being selected for queries. On Linux you need these two commands to be able to use the freebind socket option to receive traffic for the ip6 netblock: NDENT 7.0 NDENT 3.5
ip -6 addr add mynetblock/64 dev lo && \e ip -6 route add local mynetblock/64 dev loNINDENT NINDENT NINDENT NDENT 0.0
outgoing-range: <number> Number of ports to open. This number of file descriptors can be opened per thread. Must be at least 1. Default depends on compile options. Larger numbers need extra resources from the operating system. For performance a very large value is best, use libevent to make this possible. Default: 4096 (libevent) / 960 (minievent) / 48 (windows) NINDENT NDENT 0.0
outgoing-port-permit: <port number or range> Permit Unbound to open this port or range of ports for use to send queries. A larger number of permitted outgoing ports increases resilience against spoofing attempts. Make sure these ports are not needed by other daemons. By default only ports above 1024 that have not been assigned by IANA are used. Give a port number or a range of the form \(dqlow-high\(dq, without spaces. The \%outgoing-port-permit and \%outgoing-port-avoid statements are processed in the line order of the config file, adding the permitted ports and subtracting the avoided ports from the set of allowed ports. The processing starts with the non IANA allocated ports above 1024 in the set of allowed ports. NINDENT NDENT 0.0
outgoing-port-avoid: <port number or range> Do not permit Unbound to open this port or range of ports for use to send queries. Use this to make sure Unbound does not grab a port that another daemon needs. The port is avoided on all outgoing interfaces, both IPv4 and IPv6. By default only ports above 1024 that have not been assigned by IANA are used. Give a port number or a range of the form \(dqlow-high\(dq, without spaces. NINDENT NDENT 0.0
outgoing-num-tcp: <number> Number of outgoing TCP buffers to allocate per thread. If set to 0, or if \%do-tcp: no is set, no TCP queries to authoritative servers are done. For larger installations increasing this value is a good idea. Default: 10 NINDENT NDENT 0.0
incoming-num-tcp: <number> Number of incoming TCP buffers to allocate per thread. If set to 0, or if \%do-tcp: no is set, no TCP queries from clients are accepted. For larger installations increasing this value is a good idea. Default: 10 NINDENT NDENT 0.0
edns-buffer-size: <number> Number of bytes size to advertise as the EDNS reassembly buffer size. This is the value put into datagrams over UDP towards peers. The actual buffer size is determined by \%msg-buffer-size (both for TCP and UDP). Do not set higher than that value. Setting to 512 bypasses even the most stringent path MTU problems, but is seen as extreme, since the amount of TCP fallback generated is excessive (probably also for this resolver, consider tuning \%outgoing-num-tcp). Default: 1232 (\%DNS Flag Day 2020 recommendation) NINDENT NDENT 0.0
max-udp-size: <number> Maximum UDP response size (not applied to TCP response). 65536 disables the UDP response size maximum, and uses the choice from the client, always. Suggested values are 512 to 4096. Default: 1232 (same as \%edns-buffer-size) NINDENT NDENT 0.0
stream-wait-size: <number> Number of bytes size maximum to use for waiting stream buffers. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). As TCP and TLS streams queue up multiple results, the amount of memory used for these buffers does not exceed this number, otherwise the responses are dropped. This manages the total memory usage of the server (under heavy use), the number of requests that can be queued up per connection is also limited, with further requests waiting in TCP buffers. Default: 4m NINDENT NDENT 0.0
msg-buffer-size: <number> Number of bytes size of the message buffers. Default is 65552 bytes, enough for 64 Kb packets, the maximum DNS message size. No message larger than this can be sent or received. Can be reduced to use less memory, but some requests for DNS data, such as for huge resource records, will result in a SERVFAIL reply to the client. Default: 65552 NINDENT NDENT 0.0
msg-cache-size: <number> Number of bytes size of the message cache. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). Default: 4m NINDENT NDENT 0.0
msg-cache-slabs: <number> Number of slabs in the message cache. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT NDENT 0.0
num-queries-per-thread: <number> The number of queries that every thread will service simultaneously. If more queries arrive that need servicing, and no queries can be jostled out (see \%jostle-timeout), then the queries are dropped. This forces the client to resend after a timeout; allowing the server time to work on the existing queries. Default depends on compile options. Default: 2048 (libevent) / 512 (minievent) / 24 (windows) NINDENT NDENT 0.0
jostle-timeout: <msec> Timeout used when the server is very busy. Set to a value that usually results in one roundtrip to the authority servers. If too many queries arrive, then 50% of the queries are allowed to run to completion, and the other 50% are replaced with the new incoming query if they have already spent more than their allowed time. This protects against denial of service by slow queries or high query rates. The effect is that the qps for long-lasting queries is about: NDENT 7.0 NDENT 3.5
(num-queries-per-thread / 2) / (average time for such long queries) qpsNINDENT NINDENT The qps for short queries can be about: NDENT 7.0 NDENT 3.5
(num-queries-per-thread / 2) / (jostle-timeout in whole seconds) qps per threadNINDENT NINDENT about (2048/2)*5 = 5120 qps by default. Default: 200 NINDENT NDENT 0.0
delay-close: <msec> Extra delay for timeouted UDP ports before they are closed, in msec. This prevents very delayed answer packets from the upstream (recursive) servers from bouncing against closed ports and setting off all sort of close-port counters, with eg. 1500 msec. When timeouts happen you need extra sockets, it checks the ID and remote IP of packets, and unwanted packets are added to the unwanted packet counter. Default: 0 (disabled) NINDENT NDENT 0.0
udp-connect: <yes or no> Perform connect(2) for UDP sockets that mitigates ICMP side channel leakage. Default: yes NINDENT NDENT 0.0
unknown-server-time-limit: <msec> The wait time in msec for waiting for an unknown server to reply. Increase this if you are behind a slow satellite link, to eg. 1128. That would then avoid re-querying every initial query because it times out. Default: 376 NINDENT NDENT 0.0
discard-timeout: <msec> The wait time in msec where recursion requests are dropped. This is to stop a large number of replies from accumulating. They receive no reply, the work item continues to recurse. It is nice to be a bit larger than \%serve-expired-client-timeout if that is enabled. A value of 1900 msec is suggested. The value 0 disables it. Default: 1900 NINDENT NDENT 0.0
wait-limit: <number> The number of replies that can wait for recursion, for an IP address. This makes a ratelimit per IP address of waiting replies for recursion. It stops very large amounts of queries waiting to be returned to one destination. The value 0 disables wait limits. Default: 1000 NINDENT NDENT 0.0
wait-limit-cookie: <number> The number of replies that can wait for recursion, for an IP address that sent the query with a valid DNS Cookie. Since the cookie validates the client address, this limit can be higher. Default: 10000 NINDENT NDENT 0.0
wait-limit-netblock: <netblock> <number> The wait limit for the netblock. If not given the \%wait-limit value is used. The most specific netblock is used to determine the limit. Useful for overriding the default for a specific, group or individual, server. The value -1 disables wait limits for the netblock. By default the loopback has a wait limit netblock of -1, it is not limited, because it is separated from the rest of network for spoofed packets. The loopback addresses 127.0.0.0/8 and ::1/128 are default at -1. Default: (none) NINDENT NDENT 0.0
wait-limit-cookie-netblock: <netblock> <number> The wait limit for the netblock, when the query has a DNS Cookie. If not given, the \%wait-limit-cookie value is used. The value -1 disables wait limits for the netblock. The loopback addresses 127.0.0.0/8 and ::1/128 are default at -1. Default: (none) NINDENT NDENT 0.0
so-rcvbuf: <number> If not 0, then set the SO_RCVBUF socket option to get more buffer space on UDP port 53 incoming queries. So that short spikes on busy servers do not drop packets (see counter in netstat -su). Otherwise, the number of bytes to ask for, try \(dq4m\(dq on a busy server. The OS caps it at a maximum, on linux Unbound needs root permission to bypass the limit, or the admin can use sysctl net.core.rmem_max. On BSD change kern.ipc.maxsockbuf in /etc/sysctl.conf. On OpenBSD change header and recompile kernel. On Solaris ndd -set /dev/udp udp_max_buf 8388608. Default: 0 (use system value) NINDENT NDENT 0.0
so-sndbuf: <number> If not 0, then set the SO_SNDBUF socket option to get more buffer space on UDP port 53 outgoing queries. This for very busy servers handles spikes in answer traffic, otherwise: NDENT 7.0 NDENT 3.5
send: resource temporarily unavailableNINDENT NINDENT can get logged, the buffer overrun is also visible by netstat -su. If set to 0 it uses the system value. Specify the number of bytes to ask for, try \(dq8m\(dq on a very busy server. It needs some space to be able to deal with packets that wait for local address resolution, from like ARP and NDP discovery, before they are sent out, hence it is elevated above the system default by default. The OS caps it at a maximum, on linux Unbound needs root permission to bypass the limit, or the admin can use sysctl net.core.wmem_max. On BSD, Solaris changes are similar to \%so-rcvbuf. Default: 4m NINDENT NDENT 0.0
so-reuseport: <yes or no> If yes, then open dedicated listening sockets for incoming queries for each thread and try to set the SO_REUSEPORT socket option on each socket. May distribute incoming queries to threads more evenly. On Linux it is supported in kernels >= 3.9. On other systems, FreeBSD, OSX it may also work. You can enable it (on any platform and kernel), it then attempts to open the port and passes the option if it was available at compile time, if that works it is used, if it fails, it continues silently (unless verbosity 3) without the option. At extreme load it could be better to turn it off to distribute the queries evenly, reported for Linux systems (4.4.x). Default: yes NINDENT NDENT 0.0
ip-transparent: <yes or no> If yes, then use IP_TRANSPARENT socket option on sockets where Unbound is listening for incoming traffic. Allows you to bind to non-local interfaces. For example for non-existent IP addresses that are going to exist later on, with host failover configuration. This is a lot like \%interface-automatic, but that one services all interfaces and with this option you can select which (future) interfaces Unbound provides service on. This option needs Unbound to be started with root permissions on some systems. The option uses IP_BINDANY on FreeBSD systems and SO_BINDANY on OpenBSD systems. Default: no NINDENT NDENT 0.0
ip-freebind: <yes or no> If yes, then use IP_FREEBIND socket option on sockets where Unbound is listening to incoming traffic. Allows you to bind to IP addresses that are nonlocal or do not exist, like when the network interface or IP address is down. Exists only on Linux, where the similar \%ip-transparent option is also available. Default: no NINDENT NDENT 0.0
ip-dscp: <number> The value of the Differentiated Services Codepoint (DSCP) in the differentiated services field (DS) of the outgoing IP packet headers. The field replaces the outdated IPv4 Type-Of-Service field and the IPv6 traffic class field. NINDENT NDENT 0.0
rrset-cache-size: <number> Number of bytes size of the RRset cache. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). Default: 4m NINDENT NDENT 0.0
rrset-cache-slabs: <number> Number of slabs in the RRset cache. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT NDENT 0.0
cache-max-ttl: <seconds> Time to live maximum for RRsets and messages in the cache. When the TTL expires, the cache item has expired. Can be set lower to force the resolver to query for data often, and not trust (very large) TTL values. Downstream clients also see the lower TTL. Default: 86400 (1 day) NINDENT NDENT 0.0
cache-min-ttl: <seconds> Time to live minimum for RRsets and messages in the cache. If the minimum kicks in, the data is cached for longer than the domain owner intended, and thus less queries are made to look up the data. Zero makes sure the data in the cache is as the domain owner intended, higher values, especially more than an hour or so, can lead to trouble as the data in the cache does not match up with the actual data any more. Default: 0 (disabled) NINDENT NDENT 0.0
cache-max-negative-ttl: <seconds> Time to live maximum for negative responses, these have a SOA in the authority section that is limited in time. This applies to NXDOMAIN and NODATA answers. Default: 3600 NINDENT NDENT 0.0
cache-min-negative-ttl: <seconds> Time to live minimum for negative responses, these have a SOA in the authority section that is limited in time. If this is disabled and \%cache-min-ttl is configured, it will take effect instead. In that case you can set this to 1 to honor the upstream TTL. This applies to NXDOMAIN and NODATA answers. Default: 0 (disabled) NINDENT NDENT 0.0
infra-host-ttl: <seconds> Time to live for entries in the host cache. The host cache contains roundtrip timing, lameness and EDNS support information. Default: 900 NINDENT NDENT 0.0
infra-cache-slabs: <number> Number of slabs in the infrastructure cache. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT NDENT 0.0
infra-cache-numhosts: <number> Number of hosts for which information is cached. Default: 10000 NINDENT NDENT 0.0
infra-cache-min-rtt: <msec> Lower limit for dynamic retransmit timeout calculation in infrastructure cache. Increase this value if using forwarders needing more time to do recursive name resolution. Default: 50 NINDENT NDENT 0.0
infra-cache-max-rtt: <msec> Upper limit for dynamic retransmit timeout calculation in infrastructure cache. Default: 120000 (2 minutes) NINDENT NDENT 0.0
infra-keep-probing: <yes or no> If enabled the server keeps probing hosts that are down, in the one probe at a time regime. Hosts that are down, eg. they did not respond during the one probe at a time period, are marked as down and it may take \%infra-host-ttl time to get probed again. Default: no NINDENT NDENT 0.0
define-tag: \(dq<list of tags>\(dq Define the tags that can be used with \%local-zone and \%access-control. Enclose the list between quotes (\(dq\(dq) and put spaces between tags. NINDENT NDENT 0.0
do-ip4: <yes or no> Enable or disable whether IPv4 queries are answered or issued. Default: yes NINDENT NDENT 0.0
do-ip6: <yes or no> Enable or disable whether IPv6 queries are answered or issued. If disabled, queries are not answered on IPv6, and queries are not sent on IPv6 to the internet nameservers. With this option you can disable the IPv6 transport for sending DNS traffic, it does not impact the contents of the DNS traffic, which may have IPv4 (A) and IPv6 (AAAA) addresses in it. Default: yes NINDENT NDENT 0.0
prefer-ip4: <yes or no> If enabled, prefer IPv4 transport for sending DNS queries to internet nameservers. Useful if the IPv6 netblock the server has, the entire /64 of that is not owned by one operator and the reputation of the netblock /64 is an issue, using IPv4 then uses the IPv4 filters that the upstream servers have. Default: no NINDENT NDENT 0.0
prefer-ip6: <yes or no> If enabled, prefer IPv6 transport for sending DNS queries to internet nameservers. Default: no NINDENT NDENT 0.0
do-udp: <yes or no> Enable or disable whether UDP queries are answered or issued. Default: yes NINDENT NDENT 0.0
do-tcp: <yes or no> Enable or disable whether TCP queries are answered or issued. Default: yes NINDENT NDENT 0.0
tcp-mss: <number> Maximum segment size (MSS) of TCP socket on which the server responds to queries. Value lower than common MSS on Ethernet (1220 for example) will address path MTU problem. Note that not all platform supports socket option to set MSS (TCP_MAXSEG). Default is system default MSS determined by interface MTU and negotiation between server and client. NINDENT NDENT 0.0
outgoing-tcp-mss: <number> Maximum segment size (MSS) of TCP socket for outgoing queries (from Unbound to other servers). Value lower than common MSS on Ethernet (1220 for example) will address path MTU problem. Note that not all platform supports socket option to set MSS (TCP_MAXSEG). Default is system default MSS determined by interface MTU and negotiation between Unbound and other servers. NINDENT NDENT 0.0
tcp-idle-timeout: <msec> The period Unbound will wait for a query on a TCP connection. If this timeout expires Unbound closes the connection. When the number of free incoming TCP buffers falls below 50% of the total number configured, the option value used is progressively reduced, first to 1% of the configured value, then to 0.2% of the configured value if the number of free buffers falls below 35% of the total number configured, and finally to 0 if the number of free buffers falls below 20% of the total number configured. A minimum timeout of 200 milliseconds is observed regardless of the option value used. It will be overridden by \%edns-tcp-keepalive-timeout if \%edns-tcp-keepalive is enabled. Default: 30000 (30 seconds) NINDENT NDENT 0.0
tcp-reuse-timeout: <msec> The period Unbound will keep TCP persistent connections open to authority servers. Default: 60000 (60 seconds) NINDENT NDENT 0.0
max-reuse-tcp-queries: <number> The maximum number of queries that can be sent on a persistent TCP connection. Default: 200 NINDENT NDENT 0.0
tcp-auth-query-timeout: <number> Timeout in milliseconds for TCP queries to auth servers. Default: 3000 (3 seconds) NINDENT NDENT 0.0
edns-tcp-keepalive: <yes or no> Enable or disable EDNS TCP Keepalive. Default: no NINDENT NDENT 0.0
edns-tcp-keepalive-timeout: <msec> Overrides \%tcp-idle-timeout when \%edns-tcp-keepalive is enabled. If the client supports the EDNS TCP Keepalive option, If the client supports the EDNS TCP Keepalive option, Unbound sends the timeout value to the client to encourage it to close the connection before the server times out. Default: 120000 (2 minutes) NINDENT NDENT 0.0
sock-queue-timeout: <sec> UDP queries that have waited in the socket buffer for a long time can be dropped. The time is set in seconds, 3 could be a good value to ignore old queries that likely the client does not need a reply for any more. This could happen if the host has not been able to service the queries for a while, i.e. Unbound is not running, and then is enabled again. It uses timestamp socket options. The socket option is available on the Linux and FreeBSD platforms. Default: 0 (disabled) NINDENT NDENT 0.0
tcp-upstream: <yes or no> Enable or disable whether the upstream queries use TCP only for transport. Useful in tunneling scenarios. If set to no you can specify TCP transport only for selected forward or stub zones using \%forward-tcp-upstream or \%stub-tcp-upstream respectively. Default: no NINDENT NDENT 0.0
udp-upstream-without-downstream: <yes or no> Enable UDP upstream even if \%do-udp: no is set. Useful for TLS service providers, that want no UDP downstream but use UDP to fetch data upstream. Default: no (no changes) NINDENT NDENT 0.0
tls-upstream: <yes or no> Enabled or disable whether the upstream queries use TLS only for transport. Useful in tunneling scenarios. The TLS contains plain DNS in TCP wireformat. The other server must support this (see \%tls-service-key). If you enable this, also configure a \%tls-cert-bundle or use \%tls-win-cert or \%tls-system-cert to load CA certs, otherwise the connections cannot be authenticated. This option enables TLS for all of them, but if you do not set this you can configure TLS specifically for some forward zones with \%forward-tls-upstream. And also with \%stub-tls-upstream. If the \%tls-upstream option is enabled, it is for all the forwards and stubs, where the \%forward-tls-upstream and \%stub-tls-upstream options are ignored, as if they had been set to yes. Default: no NINDENT NDENT 0.0
ssl-upstream: <yes or no> Alternate syntax for \%tls-upstream. If both are present in the config file the last is used. NINDENT NDENT 0.0
tls-service-key: <file> If enabled, the server provides DNS-over-TLS or DNS-over-HTTPS service on the TCP ports marked implicitly or explicitly for these services with \%tls-port or \%https-port. The file must contain the private key for the TLS session, the public certificate is in the \%tls-service-pem file and it must also be specified if \%tls-service-key is specified. Enabling or disabling this service requires a restart (a reload is not enough), because the key is read while root permissions are held and before chroot (if any). The ports enabled implicitly or explicitly via \%tls-port and \%https-port do not provide normal DNS TCP service. NOTE: NDENT 7.0 NDENT 3.5 Unbound needs to be compiled with libnghttp2 in order to provide DNS-over-HTTPS. NINDENT NINDENT Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
ssl-service-key: <file> Alternate syntax for \%tls-service-key. NINDENT NDENT 0.0
tls-service-pem: <file> The public key certificate pem file for the tls service. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
ssl-service-pem: <file> Alternate syntax for \%tls-service-pem. NINDENT NDENT 0.0
tls-port: <number> The port number on which to provide TCP TLS service. Only interfaces configured with that port number as @number get the TLS service. Default: 853 NINDENT NDENT 0.0
ssl-port: <number> Alternate syntax for \%tls-port. NINDENT NDENT 0.0
tls-cert-bundle: <file> If null or \(dq\(dq, no file is used. Set it to the certificate bundle file, for example /etc/pki/tls/certs/ca-bundle.crt. These certificates are used for authenticating connections made to outside peers. For example \%auth-zone urls, and also DNS-over-TLS connections. It is read at start up before permission drop and chroot. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
ssl-cert-bundle: <file> Alternate syntax for \%tls-cert-bundle. NINDENT NDENT 0.0
tls-win-cert: <yes or no> Add the system certificates to the cert bundle certificates for authentication. If no cert bundle, it uses only these certificates. On windows this option uses the certificates from the cert store. Use the \%tls-cert-bundle option on other systems. On other systems, this option enables the system certificates. Default: no NINDENT NDENT 0.0
tls-system-cert: <yes or no> This the same attribute as the \%tls-win-cert attribute, under a different name. Because it is not windows specific. NINDENT NDENT 0.0
tls-additional-port: <portnr> List port numbers as \%tls-additional-port, and when interfaces are defined, eg. with the @port suffix, as this port number, they provide DNS-over-TLS service. Can list multiple, each on a new statement. NINDENT NDENT 0.0
tls-session-ticket-keys: <file> If not \(dq\(dq, lists files with 80 bytes of random contents that are used to perform TLS session resumption for clients using the Unbound server. These files contain the secret key for the TLS session tickets. First key use to encrypt and decrypt TLS session tickets. Other keys use to decrypt only. With this you can roll over to new keys, by generating a new first file and allowing decrypt of the old file by listing it after the first file for some time, after the wait clients are not using the old key any more and the old key can be removed. One way to create the file is: NDENT 7.0 NDENT 3.5
dd if=/dev/random bs=1 count=80 of=ticket.datNINDENT NINDENT The first 16 bytes should be different from the old one if you create a second key, that is the name used to identify the key. Then there is 32 bytes random data for an AES key and then 32 bytes random data for the HMAC key. Default: \(dq\(dq NINDENT NDENT 0.0
tls-ciphers: <string with cipher list> Set the list of ciphers to allow when serving TLS. Use \(dq\(dq for default ciphers. Default: \(dq\(dq NINDENT NDENT 0.0
tls-ciphersuites: <string with ciphersuites list> Set the list of ciphersuites to allow when serving TLS. This is for newer TLS 1.3 connections. Use \(dq\(dq for default ciphersuites. Default: \(dq\(dq NINDENT NDENT 0.0
pad-responses: <yes or no> If enabled, TLS serviced queries that contained an EDNS Padding option will cause responses padded to the closest multiple of the size specified in \%pad-responses-block-size. Default: yes NINDENT NDENT 0.0
pad-responses-block-size: <number> The block size with which to pad responses serviced over TLS. Only responses to padded queries will be padded. Default: 468 NINDENT NDENT 0.0
pad-queries: <yes or no> If enabled, all queries sent over TLS upstreams will be padded to the closest multiple of the size specified in \%pad-queries-block-size. Default: yes NINDENT NDENT 0.0
pad-queries-block-size: <number> The block size with which to pad queries sent over TLS upstreams. Default: 128 NINDENT NDENT 0.0
tls-use-sni: <yes or no> Enable or disable sending the SNI extension on TLS connections. NOTE: NDENT 7.0 NDENT 3.5 Changing the value requires a reload. NINDENT NINDENT Default: yes NINDENT NDENT 0.0
https-port: <number> The port number on which to provide DNS-over-HTTPS service. Only interfaces configured with that port number as @number get the HTTPS service. Default: 443 NINDENT NDENT 0.0
http-endpoint: <endpoint string> The HTTP endpoint to provide DNS-over-HTTPS service on. Default: /dns-query NINDENT NDENT 0.0
http-max-streams: <number of streams> Number used in the SETTINGS_MAX_CONCURRENT_STREAMS parameter in the HTTP/2 SETTINGS frame for DNS-over-HTTPS connections. Default: 100 NINDENT NDENT 0.0
http-query-buffer-size: <size in bytes> Maximum number of bytes used for all HTTP/2 query buffers combined. These buffers contain (partial) DNS queries waiting for request stream completion. An RST_STREAM frame will be send to streams exceeding this limit. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). Default: 4m NINDENT NDENT 0.0
http-response-buffer-size: <size in bytes> Maximum number of bytes used for all HTTP/2 response buffers combined. These buffers contain DNS responses waiting to be written back to the clients. An RST_STREAM frame will be send to streams exceeding this limit. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). Default: 4m NINDENT NDENT 0.0
http-nodelay: <yes or no> Set TCP_NODELAY socket option on sockets used to provide DNS-over-HTTPS service. Ignored if the option is not available. Default: yes NINDENT NDENT 0.0
http-notls-downstream: <yes or no> Disable use of TLS for the downstream DNS-over-HTTP connections. Useful for local back end servers. Default: no NINDENT NDENT 0.0
proxy-protocol-port: <portnr> List port numbers as \%proxy-protocol-port, and when interfaces are defined, eg. with the @port suffix, as this port number, they support and expect PROXYv2. In this case the proxy address will only be used for the network communication and initial ACL (check if the proxy itself is denied/refused by configuration). The proxied address (if any) will then be used as the true client address and will be used where applicable for logging, ACL, DNSTAP, RPZ and IP ratelimiting. PROXYv2 is supported for UDP and TCP/TLS listening interfaces. There is no support for PROXYv2 on a DoH, DoQ or DNSCrypt listening interface. Can list multiple, each on a new statement. NINDENT NDENT 0.0
quic-port: <number> The port number on which to provide DNS-over-QUIC service. Only interfaces configured with that port number as @number get the QUIC service. The interface uses QUIC for the UDP traffic on that port number. Default: 853 NINDENT NDENT 0.0
quic-size: <size in bytes> Maximum number of bytes for all QUIC buffers and data combined. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). New connections receive connection refused when the limit is exceeded. New streams are reset when the limit is exceeded. Default: 8m NINDENT NDENT 0.0
use-systemd: <yes or no> Enable or disable systemd socket activation. Default: no NINDENT NDENT 0.0
do-daemonize: <yes or no> Enable or disable whether the Unbound server forks into the background as a daemon. Set the value to no when Unbound runs as systemd service. Default: yes NINDENT NDENT 0.0
tcp-connection-limit: <IP netblock> <limit> Allow up to limit simultaneous TCP connections from the given netblock. When at the limit, further connections are accepted but closed immediately. This option is experimental at this time. Default: (disabled) NINDENT NDENT 0.0
access-control: <IP netblock> <action> Specify treatment of incoming queries from their originating IP address. Queries can be allowed to have access to this server that gives DNS answers, or refused, with other actions possible. The IP address range can be specified as a netblock, it is possible to give the statement several times in order to specify the treatment of different netblocks. The netblock is given as an IPv4 or IPv6 address with /size appended for a classless network block. The most specific netblock match is used, if none match \%refuse is used. The order of the access-control statements therefore does not matter. The action can be \%deny, \%refuse, \%allow, \%allow_setrd, \%allow_snoop, \%allow_cookie, \%deny_non_local or \%refuse_non_local. NDENT 7.0
deny Stops queries from hosts from that netblock. NINDENT NDENT 7.0
refuse Stops queries too, but sends a DNS rcode REFUSED error message back. NINDENT NDENT 7.0
allow Gives access to clients from that netblock. It gives only access for recursion clients (which is what almost all clients need). Non-recursive queries are refused. The \%allow action does allow non-recursive queries to access the local-data that is configured. The reason is that this does not involve the Unbound server recursive lookup algorithm, and static data is served in the reply. This supports normal operations where non-recursive queries are made for the authoritative data. For non-recursive queries any replies from the dynamic cache are refused. NINDENT NDENT 7.0
allow_setrd Ignores the recursion desired (RD) bit and treats all requests as if the recursion desired bit is set. Note that this behavior violates \%RFC 1034 which states that a name server should never perform recursive service unless asked via the RD bit since this interferes with trouble shooting of name servers and their databases. This prohibited behavior may be useful if another DNS server must forward requests for specific zones to a resolver DNS server, but only supports stub domains and sends queries to the resolver DNS server with the RD bit cleared. NINDENT NDENT 7.0
allow_snoop Gives non-recursive access too. This gives both recursive and non recursive access. The name allow_snoop refers to cache snooping, a technique to use non-recursive queries to examine the cache contents (for malicious acts). However, non-recursive queries can also be a valuable debugging tool (when you want to examine the cache contents). In that case use \%allow_snoop for your administration host. NINDENT NDENT 7.0
allow_cookie Allows access only to UDP queries that contain a valid DNS Cookie as specified in RFC 7873 and RFC 9018, when the \%answer-cookie option is enabled. UDP queries containing only a DNS Client Cookie and no Server Cookie, or an invalid DNS Cookie, will receive a BADCOOKIE response including a newly generated DNS Cookie, allowing clients to retry with that DNS Cookie. The allow_cookie action will also accept requests over stateful transports, regardless of the presence of an DNS Cookie and regardless of the \%answer-cookie setting. UDP queries without a DNS Cookie receive REFUSED responses with the TC flag set, that may trigger fall back to TCP for those clients. NINDENT NDENT 7.0
deny_non_local The \%deny_non_local action is for hosts that are only allowed to query for the authoritative \%local-data, they are not allowed full recursion but only the static data. Messages that are disallowed are dropped. NINDENT NDENT 7.0
refuse_non_local The \%refuse_non_local action is for hosts that are only allowed to query for the authoritative \%local-data, they are not allowed full recursion but only the static data. Messages that are disallowed receive error code REFUSED. NINDENT By default only localhost (the 127.0.0.0/8 IP netblock, not the loopback interface) is implicitly allowed, the rest is refused. The default is refused, because that is protocol-friendly. The DNS protocol is not designed to handle dropped packets due to policy, and dropping may result in (possibly excessive) retried queries. NINDENT NDENT 0.0
access-control-tag: <IP netblock> \(dq<list of tags>\(dq Assign tags to \%access-control elements. Clients using this access control element use localzones that are tagged with one of these tags. Tags must be defined in \%define-tag. Enclose list of tags in quotes (\(dq\(dq) and put spaces between tags. If \%access-control-tag is configured for a netblock that does not have an \%access-control, an access-control element with action \%allow is configured for this netblock. NINDENT NDENT 0.0
access-control-tag-action: <IP netblock> <tag> <action> Set action for particular tag for given access control element. If you have multiple tag values, the tag used to lookup the action is the first tag match between \%access-control-tag and \%local-zone-tag where \(dqfirst\(dq comes from the order of the \%define-tag values. NINDENT NDENT 0.0
access-control-tag-data: <IP netblock> <tag> \(dq<resource record string>\(dq Set redirect data for particular tag for given access control element. NINDENT NDENT 0.0
access-control-view: <IP netblock> <view name> Set view for given access control element. NINDENT NDENT 0.0
interface-action: <ip address or interface name [@port]> <action> Similar to \%access-control but for interfaces. The action is the same as the ones defined under \%access-control. Default action for interfaces is \%refuse. By default only localhost (the 127.0.0.0/8 IP netblock, not the loopback interface) is implicitly allowed through the default \%access-control behavior. This also means that any attempt to use the interface-*: options for the loopback interface will not work as they will be overridden by the implicit default \(dqaccess-control: 127.0.0.0/8 allow\(dq option. NOTE: NDENT 7.0 NDENT 3.5 The interface needs to be already specified with \%interface and that any access-control*: attribute overrides all interface-*: attributes for targeted clients. NINDENT NINDENT NINDENT NDENT 0.0
interface-tag: <ip address or interface name [@port]> <\(dqlist of tags\(dq> Similar to \%access-control-tag but for interfaces. NOTE: NDENT 7.0 NDENT 3.5 The interface needs to be already specified with \%interface and that any access-control*: attribute overrides all interface-*: attributes for targeted clients. NINDENT NINDENT NINDENT NDENT 0.0
interface-tag-action: <ip address or interface name [@port]> <tag> <action> Similar to \%access-control-tag-action but for interfaces. NOTE: NDENT 7.0 NDENT 3.5 The interface needs to be already specified with \%interface and that any access-control*: attribute overrides all interface-*: attributes for targeted clients. NINDENT NINDENT NINDENT NDENT 0.0
interface-tag-data: <ip address or interface name [@port]> <tag> <\(dqresource record string\(dq> Similar to \%access-control-tag-data but for interfaces. NOTE: NDENT 7.0 NDENT 3.5 The interface needs to be already specified with \%interface and that any access-control*: attribute overrides all interface-*: attributes for targeted clients. NINDENT NINDENT NINDENT NDENT 0.0
interface-view: <ip address or interface name [@port]> <view name> Similar to \%access-control-view but for interfaces. NOTE: NDENT 7.0 NDENT 3.5 The interface needs to be already specified with \%interface and that any access-control*: attribute overrides all interface-*: attributes for targeted clients. NINDENT NINDENT NINDENT NDENT 0.0
chroot: <directory> If \%chroot is enabled, you should pass the configfile (from the commandline) as a full path from the original root. After the chroot has been performed the now defunct portion of the config file path is removed to be able to reread the config after a reload. All other file paths (working dir, logfile, roothints, and key files) can be specified in several ways: as an absolute path relative to the new root, as a relative path to the working directory, or as an absolute path relative to the original root. In the last case the path is adjusted to remove the unused portion. The pidfile can be either a relative path to the working directory, or an absolute path relative to the original root. It is written just prior to chroot and dropping permissions. This allows the pidfile to be /var/run/unbound.pid and the chroot to be /var/unbound, for example. Note that Unbound is not able to remove the pidfile after termination when it is located outside of the chroot directory. Additionally, Unbound may need to access /dev/urandom (for entropy) from inside the chroot. If given, a chroot(2) is done to the given directory. If you give \(dq\(dq no chroot(2) is performed. Default: @UNBOUND_CHROOT_DIR@ NINDENT NDENT 0.0
username: <name> If given, after binding the port the user privileges are dropped. If you give username: \(dq\(dq no user change is performed. If this user is not capable of binding the port, reloads (by signal HUP) will still retain the opened ports. If you change the port number in the config file, and that new port number requires privileges, then a reload will fail; a restart is needed. Default: @UNBOUND_USERNAME@ NINDENT NDENT 0.0
directory: <directory> Sets the working directory for the program. On Windows the string \(dq%EXECUTABLE%\(dq tries to change to the directory that unbound.exe resides in. If you give a \%server: directory: <directory> before \%include file statements then those includes can be relative to the working directory. Default: @UNBOUND_RUN_DIR@ NINDENT NDENT 0.0
logfile: <filename> If \(dq\(dq is given, logging goes to stderr, or nowhere once daemonized. The logfile is appended to, in the following format: NDENT 7.0 NDENT 3.5
[seconds since 1970] unbound[pid:tid]: type: message.NINDENT NINDENT If this option is given, the \%use-syslog attribute is internally set to no. The logfile is reopened (for append) when the config file is reread, on SIGHUP. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
use-syslog: <yes or no> Sets Unbound to send log messages to the syslogd, using syslog(3). The log facility LOG_DAEMON is used, with identity \(dqunbound\(dq. The logfile setting is overridden when \%use-syslog: yes is set. Default: yes NINDENT NDENT 0.0
log-identity: <string> If \(dq\(dq is given, then the name of the executable, usually \(dqunbound\(dq is used to report to the log. Enter a string to override it with that, which is useful on systems that run more than one instance of Unbound, with different configurations, so that the logs can be easily distinguished against. Default: \(dq\(dq NINDENT NDENT 0.0
log-time-ascii: <yes or no> Sets logfile lines to use a timestamp in UTC ASCII. No effect if using syslog, in that case syslog formats the timestamp printed into the log files. Default: no (prints the seconds since 1970 in brackets) NINDENT NDENT 0.0
log-time-iso: <yes or no> Log time in ISO8601 format, if \%log-time-ascii: yes is also set. Default: no NINDENT NDENT 0.0
log-queries: <yes or no> Prints one line per query to the log, with the log timestamp and IP address, name, type and class. Note that it takes time to print these lines which makes the server (significantly) slower. Odd (nonprintable) characters in names are printed as \(aq?\(aq. Default: no NINDENT NDENT 0.0
log-replies: <yes or no> Prints one line per reply to the log, with the log timestamp and IP address, name, type, class, return code, time to resolve, from cache and response size. Note that it takes time to print these lines which makes the server (significantly) slower. Odd (nonprintable) characters in names are printed as \(aq?\(aq. Default: no NINDENT NDENT 0.0
log-tag-queryreply: <yes or no> Prints the word \(aqquery\(aq and \(aqreply\(aq with \%log-queries and \%log-replies. This makes filtering logs easier. Default: no (backwards compatible) NINDENT NDENT 0.0
log-destaddr: <yes or no> Prints the destination address, port and type in the \%log-replies output. This disambiguates what type of traffic, eg. UDP or TCP, and to what local port the traffic was sent to. Default: no NINDENT NDENT 0.0
log-local-actions: <yes or no> Print log lines to inform about local zone actions. These lines are like the \%local-zone type inform print outs, but they are also printed for the other types of local zones. Default: no NINDENT NDENT 0.0
log-servfail: <yes or no> Print log lines that say why queries return SERVFAIL to clients. This is separate from the verbosity debug logs, much smaller, and printed at the error level, not the info level of debug info from verbosity. Default: no NINDENT NDENT 0.0
pidfile: <filename> The process id is written to the file. Default is \(dq@UNBOUND_PIDFILE@\(dq. So, NDENT 7.0 NDENT 3.5
kill -HUP \(gacat @UNBOUND_PIDFILE@\(gaNINDENT NINDENT triggers a reload, NDENT 7.0 NDENT 3.5
kill -TERM \(gacat @UNBOUND_PIDFILE@\(gaNINDENT NINDENT gracefully terminates. Default: @UNBOUND_PIDFILE@ NINDENT NDENT 0.0
root-hints: <filename> Read the root hints from this file. Default is nothing, using builtin hints for the IN class. The file has the format of zone files, with root nameserver names and addresses only. The default may become outdated, when servers change, therefore it is good practice to use a root hints file. Default: \(dq\(dq NINDENT NDENT 0.0
hide-identity: <yes or no> If enabled \(aqid.server\(aq and \(aqhostname.bind\(aq queries are REFUSED. Default: no NINDENT NDENT 0.0
identity: <string> Set the identity to report. If set to \(dq\(dq, then the hostname of the server is returned. Default: \(dq\(dq NINDENT NDENT 0.0
hide-version: <yes or no> If enabled \(aqversion.server\(aq and \(aqversion.bind\(aq queries are REFUSED. Default: no NINDENT NDENT 0.0
version: <string> Set the version to report. If set to \(dq\(dq, then the package version is returned. Default: \(dq\(dq NINDENT NDENT 0.0
hide-http-user-agent: <yes or no> If enabled the HTTP header User-Agent is not set. Use with caution as some webserver configurations may reject HTTP requests lacking this header. If needed, it is better to explicitly set the \%http-user-agent below. Default: no NINDENT NDENT 0.0
http-user-agent: <string> Set the HTTP User-Agent header for outgoing HTTP requests. If set to \(dq\(dq, then the package name and version are used. Default: \(dq\(dq NINDENT NDENT 0.0
nsid: <string> Add the specified nsid to the EDNS section of the answer when queried with an NSID EDNS enabled packet. As a sequence of hex characters or with \(aqascii_\(aq prefix and then an ASCII string. Default: (disabled) NINDENT NDENT 0.0
hide-trustanchor: <yes or no> If enabled \(aqtrustanchor.unbound\(aq queries are REFUSED. Default: no NINDENT NDENT 0.0
target-fetch-policy: <\(dqlist of numbers\(dq> Set the target fetch policy used by Unbound to determine if it should fetch nameserver target addresses opportunistically. The policy is described per dependency depth. The number of values determines the maximum dependency depth that Unbound will pursue in answering a query. A value of -1 means to fetch all targets opportunistically for that dependency depth. A value of 0 means to fetch on demand only. A positive value fetches that many targets opportunistically. Enclose the list between quotes (\(dq\(dq) and put spaces between numbers. Setting all zeroes, \(dq0 0 0 0 0\(dq gives behaviour closer to that of BIND 9, while setting \(dq-1 -1 -1 -1 -1\(dq gives behaviour rumoured to be closer to that of BIND 8. Default: \(dq3 2 1 0 0\(dq NINDENT NDENT 0.0
harden-short-bufsize: <yes or no> Very small EDNS buffer sizes from queries are ignored. Default: yes (as described in the standard) NINDENT NDENT 0.0
harden-large-queries: <yes or no> Very large queries are ignored. Default is no, since it is legal protocol wise to send these, and could be necessary for operation if TSIG or EDNS payload is very large. Default: no NINDENT NDENT 0.0
harden-glue: <yes or no> Will trust glue only if it is within the servers authority. Default: yes NINDENT NDENT 0.0
harden-unverified-glue: <yes or no> Will trust only in-zone glue. Will try to resolve all out of zone (unverified) glue. Will fallback to the original glue if unable to resolve. Default: no NINDENT NDENT 0.0
harden-dnssec-stripped: <yes or no> Require DNSSEC data for trust-anchored zones, if such data is absent, the zone becomes bogus. If turned off, and no DNSSEC data is received (or the DNSKEY data fails to validate), then the zone is made insecure, this behaves like there is no trust anchor. You could turn this off if you are sometimes behind an intrusive firewall (of some sort) that removes DNSSEC data from packets, or a zone changes from signed to unsigned to badly signed often. If turned off you run the risk of a downgrade attack that disables security for a zone. Default: yes NINDENT NDENT 0.0
harden-below-nxdomain: <yes or no> From \%RFC 8020 (with title \(dqNXDOMAIN: There Really Is Nothing Underneath\(dq), returns NXDOMAIN to queries for a name below another name that is already known to be NXDOMAIN. DNSSEC mandates NOERROR for empty nonterminals, hence this is possible. Very old software might return NXDOMAIN for empty nonterminals (that usually happen for reverse IP address lookups), and thus may be incompatible with this. To try to avoid this only DNSSEC-secure NXDOMAINs are used, because the old software does not have DNSSEC. NOTE: NDENT 7.0 NDENT 3.5 The NXDOMAIN must be secure, this means NSEC3 with optout is insufficient. NINDENT NINDENT Default: yes NINDENT NDENT 0.0
harden-referral-path: <yes or no> Harden the referral path by performing additional queries for infrastructure data. Validates the replies if trust anchors are configured and the zones are signed. This enforces DNSSEC validation on nameserver NS sets and the nameserver addresses that are encountered on the referral path to the answer. Default is off, because it burdens the authority servers, and it is not RFC standard, and could lead to performance problems because of the extra query load that is generated. Experimental option. If you enable it consider adding more numbers after the \%target-fetch-policy to increase the max depth that is checked to. Default: no NINDENT NDENT 0.0
harden-algo-downgrade: <yes or no> Harden against algorithm downgrade when multiple algorithms are advertised in the DS record. This works by first choosing only the strongest DS digest type as per \%RFC 4509 (Unbound treats the highest algorithm as the strongest) and then expecting signatures from all the advertised signing algorithms from the chosen DS(es) to be present. If no, allows any one supported algorithm to validate the zone, even if other advertised algorithms are broken. \%RFC 6840 mandates that zone signers must produce zones signed with all advertised algorithms, but sometimes they do not. \%RFC 6840 also clarifies that this requirement is not for validators and validators should accept any single valid path. It should thus be explicitly noted that this option violates \%RFC 6840 for DNSSEC validation and should only be used to perform a signature completeness test to support troubleshooting. WARNING: NDENT 7.0 NDENT 3.5 Using this option may break DNSSEC resolution with non \%RFC 6840 conforming signers and/or in multi-signer configurations that don\(aqt send all the advertised signatures. NINDENT NINDENT Default: no NINDENT NDENT 0.0
harden-unknown-additional: <yes or no> Harden against unknown records in the authority section and additional section. If no, such records are copied from the upstream and presented to the client together with the answer. If yes, it could hamper future protocol developments that want to add records. Default: no NINDENT NDENT 0.0
use-caps-for-id: <yes or no> Use 0x20-encoded random bits in the query to foil spoof attempts. This perturbs the lowercase and uppercase of query names sent to authority servers and checks if the reply still has the correct casing. This feature is an experimental implementation of draft dns-0x20. Default: no NINDENT NDENT 0.0
caps-exempt: <domain> Exempt the domain so that it does not receive caps-for-id perturbed queries. For domains that do not support 0x20 and also fail with fallback because they keep sending different answers, like some load balancers. Can be given multiple times, for different domains. NINDENT NDENT 0.0
caps-whitelist: <domain> Alternate syntax for \%caps-exempt. NINDENT NDENT 0.0
qname-minimisation: <yes or no> Send minimum amount of information to upstream servers to enhance privacy. Only send minimum required labels of the QNAME and set QTYPE to A when possible. Best effort approach; full QNAME and original QTYPE will be sent when upstream replies with a RCODE other than NOERROR, except when receiving NXDOMAIN from a DNSSEC signed zone. Default: yes NINDENT NDENT 0.0
qname-minimisation-strict: <yes or no> QNAME minimisation in strict mode. Do not fall-back to sending full QNAME to potentially broken nameservers. A lot of domains will not be resolvable when this option in enabled. Only use if you know what you are doing. This option only has effect when \%qname-minimisation is enabled. Default: no NINDENT NDENT 0.0
aggressive-nsec: <yes or no> Aggressive NSEC uses the DNSSEC NSEC chain to synthesize NXDOMAIN and other denials, using information from previous NXDOMAINs answers. It helps to reduce the query rate towards targets that get a very high nonexistent name lookup rate. Default: yes NINDENT NDENT 0.0
private-address: <IP address or subnet> Give IPv4 of IPv6 addresses or classless subnets. These are addresses on your private network, and are not allowed to be returned for public internet names. Any occurrence of such addresses are removed from DNS answers. Additionally, the DNSSEC validator may mark the answers bogus. This protects against so-called DNS Rebinding, where a user browser is turned into a network proxy, allowing remote access through the browser to other parts of your private network. Some names can be allowed to contain your private addresses, by default all the \%local-data that you configured is allowed to, and you can specify additional names using \%private-domain. No private addresses are enabled by default. We consider to enable this for the \%RFC 1918 private IP address space by default in later releases. That would enable private addresses for 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16, fd00::/8 and fe80::/10, since the RFC standards say these addresses should not be visible on the public internet. Turning on 127.0.0.0/8 would hinder many spamblocklists as they use that. Adding ::ffff:0:0/96 stops IPv4-mapped IPv6 addresses from bypassing the filter. NINDENT NDENT 0.0
private-domain: <domain name> Allow this domain, and all its subdomains to contain private addresses. Give multiple times to allow multiple domain names to contain private addresses. Default: (none) NINDENT NDENT 0.0
unwanted-reply-threshold: <number> If set, a total number of unwanted replies is kept track of in every thread. When it reaches the threshold, a defensive action is taken and a warning is printed to the log. The defensive action is to clear the rrset and message caches, hopefully flushing away any poison. A value of 10 million is suggested. Default: 0 (disabled) NINDENT NDENT 0.0
do-not-query-address: <IP address> Do not query the given IP address. Can be IPv4 or IPv6. Append /num to indicate a classless delegation netblock, for example like 10.2.3.4/24 or 2001::11/64. Default: (none) NINDENT NDENT 0.0
do-not-query-localhost: <yes or no> If yes, localhost is added to the \%do-not-query-address entries, both IPv6 ::1 and IPv4 127.0.0.1/8. If no, then localhost can be used to send queries to. Default: yes NINDENT NDENT 0.0
prefetch: <yes or no> If yes, cache hits on message cache elements that are on their last 10 percent of their TTL value trigger a prefetch to keep the cache up to date. Turning it on gives about 10 percent more traffic and load on the machine, but popular items do not expire from the cache. Default: no NINDENT NDENT 0.0
prefetch-key: <yes or no> If yes, fetch the DNSKEYs earlier in the validation process, when a DS record is encountered. This lowers the latency of requests. It does use a little more CPU. Also if the cache is set to 0, it is no use. Default: no NINDENT NDENT 0.0
deny-any: <yes or no> If yes, deny queries of type ANY with an empty response. If disabled, Unbound responds with a short list of resource records if some can be found in the cache and makes the upstream type ANY query if there are none. Default: no NINDENT NDENT 0.0
rrset-roundrobin: <yes or no> If yes, Unbound rotates RRSet order in response (the random number is taken from the query ID, for speed and thread safety). Default: yes NINDENT NDENT 0.0
minimal-responses: <yes or no> If yes, Unbound does not insert authority/additional sections into response messages when those sections are not required. This reduces response size significantly, and may avoid TCP fallback for some responses which may cause a slight speedup. The default is yes, even though the DNS protocol RFCs mandate these sections, and the additional content could save roundtrips for clients that use the additional content. However these sections are hardly used by clients. Enabling prefetch can benefit clients that need the additional content by trying to keep that content fresh in the cache. Default: yes NINDENT NDENT 0.0
disable-dnssec-lame-check: <yes or no> If yes, disables the DNSSEC lameness check in the iterator. This check sees if RRSIGs are present in the answer, when DNSSEC is expected, and retries another authority if RRSIGs are unexpectedly missing. The validator will insist in RRSIGs for DNSSEC signed domains regardless of this setting, if a trust anchor is loaded. Default: no NINDENT NDENT 0.0
module-config: \(dq<module names>\(dq Module configuration, a list of module names separated by spaces, surround the string with quotes (\(dq\(dq). The modules can be respip, validator, or iterator (and possibly more, see below). NOTE: NDENT 7.0 NDENT 3.5 The ordering of the modules is significant, the order decides the order of processing. NINDENT NINDENT Setting this to just \(dqiterator\(dq will result in a non-validating server. Setting this to \(dqvalidator iterator\(dq will turn on DNSSEC validation. NOTE: NDENT 7.0 NDENT 3.5 You must also set trust-anchors for validation to be useful. NINDENT NINDENT Adding respip to the front will cause RPZ processing to be done on all queries. Most modules that need to be listed here have to be listed at the beginning of the line. The subnetcache module has to be listed just before the iterator. The python module can be listed in different places, it then processes the output of the module it is just before. The dynlib module can be listed pretty much anywhere, it is only a very thin wrapper that allows dynamic libraries to run in its place. Default: \(dqvalidator iterator\(dq NINDENT NDENT 0.0
trust-anchor-file: <filename> File with trusted keys for validation. Both DS and DNSKEY entries can appear in the file. The format of the file is the standard DNS Zone file format. Default: \(dq\(dq (no trust anchor file) NINDENT NDENT 0.0
auto-trust-anchor-file: <filename> File with trust anchor for one zone, which is tracked with \%RFC 5011 probes. The probes are run several times per month, thus the machine must be online frequently. The initial file can be one with contents as described in \%trust-anchor-file. The file is written to when the anchor is updated, so the Unbound user must have write permission. Write permission to the file, but also to the directory it is in (to create a temporary file, which is necessary to deal with filesystem full events), it must also be inside the \%chroot (if that is used). Default: \(dq\(dq (no auto trust anchor file) NINDENT NDENT 0.0
trust-anchor: \(dq<Resource Record>\(dq A DS or DNSKEY RR for a key to use for validation. Multiple entries can be given to specify multiple trusted keys, in addition to the \%trust-anchor-file. The resource record is entered in the same format as dig(1) or drill(1) prints them, the same format as in the zone file. Has to be on a single line, with \(dq\(dq around it. A TTL can be specified for ease of cut and paste, but is ignored. A class can be specified, but class IN is default. Default: (none) NINDENT NDENT 0.0
trusted-keys-file: <filename> File with trusted keys for validation. Specify more than one file with several entries, one file per entry. Like \%trust-anchor-file but has a different file format. Format is BIND-9 style format, the trusted-keys { name flag proto algo \(dqkey\(dq; }; clauses are read. It is possible to use wildcards with this statement, the wildcard is expanded on start and on reload. Default: \(dq\(dq (no trusted keys file) NINDENT NDENT 0.0
trust-anchor-signaling: <yes or no> Send \%RFC 8145 key tag query after trust anchor priming. Default: yes NINDENT NDENT 0.0
root-key-sentinel: <yes or no> Root key trust anchor sentinel. Default: yes NINDENT NDENT 0.0
domain-insecure: <domain name> Sets <domain name> to be insecure, DNSSEC chain of trust is ignored towards the <domain name>. So a trust anchor above the domain name can not make the domain secure with a DS record, such a DS record is then ignored. Can be given multiple times to specify multiple domains that are treated as if unsigned. If you set trust anchors for the domain they override this setting (and the domain is secured). This can be useful if you want to make sure a trust anchor for external lookups does not affect an (unsigned) internal domain. A DS record externally can create validation failures for that internal domain. Default: (none) NINDENT NDENT 0.0
val-override-date: <rrsig-style date spec> WARNING: NDENT 7.0 NDENT 3.5 Debugging feature! NINDENT NINDENT If enabled by giving a RRSIG style date, that date is used for verifying RRSIG inception and expiration dates, instead of the current date. Do not set this unless you are debugging signature inception and expiration. The value -1 ignores the date altogether, useful for some special applications. Default: 0 (disabled) NINDENT NDENT 0.0
val-sig-skew-min: <seconds> Minimum number of seconds of clock skew to apply to validated signatures. A value of 10% of the signature lifetime (expiration - inception) is used, capped by this setting. Default is 3600 (1 hour) which allows for daylight savings differences. Lower this value for more strict checking of short lived signatures. Default: 3600 (1 hour) NINDENT NDENT 0.0
val-sig-skew-max: <seconds> Maximum number of seconds of clock skew to apply to validated signatures. A value of 10% of the signature lifetime (expiration - inception) is used, capped by this setting. Default is 86400 (24 hours) which allows for timezone setting problems in stable domains. Setting both min and max very low disables the clock skew allowances. Setting both min and max very high makes the validator check the signature timestamps less strictly. Default: 86400 (24 hours) NINDENT NDENT 0.0
val-max-restart: <number> The maximum number the validator should restart validation with another authority in case of failed validation. Default: 5 NINDENT NDENT 0.0
val-bogus-ttl: <seconds> The time to live for bogus data. This is data that has failed validation; due to invalid signatures or other checks. The TTL from that data cannot be trusted, and this value is used instead. The time interval prevents repeated revalidation of bogus data. Default: 60 NINDENT NDENT 0.0
val-clean-additional: <yes or no> Instruct the validator to remove data from the additional section of secure messages that are not signed properly. Messages that are insecure, bogus, indeterminate or unchecked are not affected. Use this setting to protect the users that rely on this validator for authentication from potentially bad data in the additional section. Default: yes NINDENT NDENT 0.0
val-log-level: <number> Have the validator print validation failures to the log. Regardless of the verbosity setting. At 1, for every user query that fails a line is printed to the logs. This way you can monitor what happens with validation. Use a diagnosis tool, such as dig or drill, to find out why validation is failing for these queries. At 2, not only the query that failed is printed but also the reason why Unbound thought it was wrong and which server sent the faulty data. Default: 0 (disabled) NINDENT NDENT 0.0
val-permissive-mode: <yes or no> Instruct the validator to mark bogus messages as indeterminate. The security checks are performed, but if the result is bogus (failed security), the reply is not withheld from the client with SERVFAIL as usual. The client receives the bogus data. For messages that are found to be secure the AD bit is set in replies. Also logging is performed as for full validation. Default: no NINDENT NDENT 0.0
ignore-cd-flag: <yes or no> Instruct Unbound to ignore the CD flag from clients and refuse to return bogus answers to them. Thus, the CD (Checking Disabled) flag does not disable checking any more. This is useful if legacy (w2008) servers that set the CD flag but cannot validate DNSSEC themselves are the clients, and then Unbound provides them with DNSSEC protection. Default: no NINDENT NDENT 0.0
disable-edns-do: <yes or no> Disable the EDNS DO flag in upstream requests. It breaks DNSSEC validation for Unbound\(aqs clients. This results in the upstream name servers to not include DNSSEC records in their replies and could be helpful for devices that cannot handle DNSSEC information. When the option is enabled, clients that set the DO flag receive no EDNS record in the response to indicate the lack of support to them. If this option is enabled but Unbound is already configured for DNSSEC validation (i.e., the validator module is enabled; default) this option is implicitly turned off with a warning as to not break DNSSEC validation in Unbound. Default: no NINDENT NDENT 0.0
serve-expired: <yes or no> If enabled, Unbound attempts to serve old responses from cache with a TTL of \%serve-expired-reply-ttl in the response. By default the expired answer will be used after a resolution attempt errored out or is taking more than \%serve-expired-client-timeout to resolve. Default: no NINDENT NDENT 0.0
serve-expired-ttl: <seconds> Limit serving of expired responses to configured seconds after expiration. 0 disables the limit. This option only applies when \%serve-expired is enabled. A suggested value per RFC 8767 is between 86400 (1 day) and 259200 (3 days). The default is 86400. Default: 86400 NINDENT NDENT 0.0
serve-expired-ttl-reset: <yes or no> Set the TTL of expired records to the \%serve-expired-ttl value after a failed attempt to retrieve the record from upstream. This makes sure that the expired records will be served as long as there are queries for it. Default: no NINDENT NDENT 0.0
serve-expired-reply-ttl: <seconds> TTL value to use when replying with expired data. If \%serve-expired-client-timeout is also used then it is RECOMMENDED to use 30 as the value (\%RFC 8767). Default: 30 NINDENT NDENT 0.0
serve-expired-client-timeout: <msec> Time in milliseconds before replying to the client with expired data. This essentially enables the serve-stale behavior as specified in \%RFC 8767 that first tries to resolve before immediately responding with expired data. Setting this to 0 will disable this behavior and instead serve the expired record immediately from the cache before attempting to refresh it via resolution. Default: 1800 NINDENT NDENT 0.0
serve-original-ttl: <yes or no> If enabled, Unbound will always return the original TTL as received from the upstream name server rather than the decrementing TTL as stored in the cache. This feature may be useful if Unbound serves as a front-end to a hidden authoritative name server. Enabling this feature does not impact cache expiry, it only changes the TTL Unbound embeds in responses to queries. NOTE: NDENT 7.0 NDENT 3.5 Enabling this feature implicitly disables enforcement of the configured minimum and maximum TTL, as it is assumed users who enable this feature do not want Unbound to change the TTL obtained from an upstream server. NINDENT NINDENT NOTE: NDENT 7.0 NDENT 3.5 The values set using \%cache-min-ttl and \%cache-max-ttl are ignored. NINDENT NINDENT Default: no NINDENT NDENT 0.0
val-nsec3-keysize-iterations: <\(dqlist of values\(dq> List of keysize and iteration count values, separated by spaces, surrounded by quotes. This determines the maximum allowed NSEC3 iteration count before a message is simply marked insecure instead of performing the many hashing iterations. The list must be in ascending order and have at least one entry. If you set it to \(dq1024 65535\(dq there is no restriction to NSEC3 iteration values. NOTE: NDENT 7.0 NDENT 3.5 This table must be kept short; a very long list could cause slower operation. NINDENT NINDENT Default: \(dq1024 150 2048 150 4096 150\(dq NINDENT NDENT 0.0
zonemd-permissive-mode: <yes or no> If enabled the ZONEMD verification failures are only logged and do not cause the zone to be blocked and only return servfail. Useful for testing out if it works, or if the operator only wants to be notified of a problem without disrupting service. Default: no NINDENT NDENT 0.0
add-holddown: <seconds> Instruct the \%auto-trust-anchor-file probe mechanism for \%RFC 5011 autotrust updates to add new trust anchors only after they have been visible for this time. Default: 2592000 (30 days as per the RFC) NINDENT NDENT 0.0
del-holddown: <seconds> Instruct the \%auto-trust-anchor-file probe mechanism for \%RFC 5011 autotrust updates to remove revoked trust anchors after they have been kept in the revoked list for this long. Default: 2592000 (30 days as per the RFC) NINDENT NDENT 0.0
keep-missing: <seconds> Instruct the \%auto-trust-anchor-file probe mechanism for \%RFC 5011 autotrust updates to remove missing trust anchors after they have been unseen for this long. This cleans up the state file if the target zone does not perform trust anchor revocation, so this makes the auto probe mechanism work with zones that perform regular (non-5011) rollovers. The value 0 does not remove missing anchors, as per the RFC. Default: 31622400 (366 days) NINDENT NDENT 0.0
permit-small-holddown: <yes or no> Debug option that allows the autotrust 5011 rollover timers to assume very small values. Default: no NINDENT NDENT 0.0
key-cache-size: <number> Number of bytes size of the key cache. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). Default: 4m NINDENT NDENT 0.0
key-cache-slabs: <number> Number of slabs in the key cache. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT NDENT 0.0
neg-cache-size: <number> Number of bytes size of the aggressive negative cache. A plain number is in bytes, append \(aqk\(aq, \(aqm\(aq or \(aqg\(aq for kilobytes, megabytes or gigabytes (1024*1024 bytes in a megabyte). Default: 1m NINDENT NDENT 0.0
unblock-lan-zones: <yes or no> If enabled, then for private address space, the reverse lookups are no longer filtered. This allows Unbound when running as dns service on a host where it provides service for that host, to put out all of the queries for the \(aqlan\(aq upstream. When enabled, only localhost, 127.0.0.1 reverse and ::1 reverse zones are configured with default local zones. Disable the option when Unbound is running as a (DHCP-) DNS network resolver for a group of machines, where such lookups should be filtered (RFC compliance), this also stops potential data leakage about the local network to the upstream DNS servers. Default: no NINDENT NDENT 0.0
insecure-lan-zones: <yes or no> If enabled, then reverse lookups in private address space are not validated. This is usually required whenever \%unblock-lan-zones is used. Default: no NINDENT NDENT 0.0
local-zone: <zone> <type> Configure a local zone. The type determines the answer to give if there is no match from \%local-data. The types are \%deny, \%refuse, \%static, \%transparent, \%redirect, \%nodefault, \%typetransparent, \%inform, \%inform_deny, \%inform_redirect, \%always_transparent, \%block_a, \%always_refuse, \%always_nxdomain, \%always_null, \%noview, and are explained below. After that the default settings are listed. Use \%local-data to enter data into the local zone. Answers for local zones are authoritative DNS answers. By default the zones are class IN. If you need more complicated authoritative data, with referrals, wildcards, CNAME/DNAME support, or DNSSEC authoritative service, setup a \%stub-zone for it as detailed in the stub zone section below. A \%stub-zone can be used to have unbound send queries to another server, an authoritative server, to fetch the information. With a \%forward-zone, unbound sends queries to a server that is a recursive server to fetch the information. With an \%auth-zone a zone can be loaded from file and used, it can be used like a local zone for users downstream, or the \%auth-zone information can be used to fetch information from when resolving like it is an upstream server. The \%forward-zone and \%auth-zone options are described in their sections below. If you want to perform filtering of the information that the users can fetch, the \%local-zone and \%local-data statements allow for this, but also the \%rpz functionality can be used, described in the RPZ section. NDENT 7.0
deny Do not send an answer, drop the query. If there is a match from local data, the query is answered. NINDENT NDENT 7.0
refuse Send an error message reply, with rcode REFUSED. If there is a match from local data, the query is answered. NINDENT NDENT 7.0
static If there is a match from local data, the query is answered. Otherwise, the query is answered with NODATA or NXDOMAIN. For a negative answer a SOA is included in the answer if present as \%local-data for the zone apex domain. NINDENT NDENT 7.0
transparent If there is a match from \%local-data, the query is answered. Otherwise if the query has a different name, the query is resolved normally. If the query is for a name given in \%local-data but no such type of data is given in localdata, then a NOERROR NODATA answer is returned. If no \%local-zone is given \%local-data causes a transparent zone to be created by default. NINDENT NDENT 7.0
typetransparent If there is a match from local data, the query is answered. If the query is for a different name, or for the same name but for a different type, the query is resolved normally. So, similar to \%transparent but types that are not listed in local data are resolved normally, so if an A record is in the local data that does not cause a NODATA reply for AAAA queries. NINDENT NDENT 7.0
redirect The query is answered from the local data for the zone name. There may be no local data beneath the zone name. This answers queries for the zone, and all subdomains of the zone with the local data for the zone. It can be used to redirect a domain to return a different address record to the end user, with: NDENT 7.0 NDENT 3.5
local-zone: \(dqexample.com.\(dq redirect local-data: \(dqexample.com. A 127.0.0.1\(dqNINDENT NINDENT queries for www.example.com and www.foo.example.com are redirected, so that users with web browsers cannot access sites with suffix example.com. NINDENT NDENT 7.0
inform The query is answered normally, same as \%transparent. The client IP address (@portnumber) is printed to the logfile. The log message is: NDENT 7.0 NDENT 3.5
timestamp, unbound-pid, info: zonename inform IP@port queryname type class.NINDENT NINDENT This option can be used for normal resolution, but machines looking up infected names are logged, eg. to run antivirus on them. NINDENT NDENT 7.0
inform_deny The query is dropped, like \%deny, and logged, like \%inform. Ie. find infected machines without answering the queries. NINDENT NDENT 7.0
inform_redirect The query is redirected, like \%redirect, and logged, like \%inform. Ie. answer queries with fixed data and also log the machines that ask. NINDENT NDENT 7.0
always_transparent Like \%transparent, but ignores local data and resolves normally. NINDENT NDENT 7.0
block_a Like \%transparent, but ignores local data and resolves normally all query types excluding A. For A queries it unconditionally returns NODATA. Useful in cases when there is a need to explicitly force all apps to use IPv6 protocol and avoid any queries to IPv4. NINDENT NDENT 7.0
always_refuse Like \%refuse, but ignores local data and refuses the query. NINDENT NDENT 7.0
always_nxdomain Like \%static, but ignores local data and returns NXDOMAIN for the query. NINDENT NDENT 7.0
always_nodata Like \%static, but ignores local data and returns NODATA for the query. NINDENT NDENT 7.0
always_deny Like \%deny, but ignores local data and drops the query. NINDENT NDENT 7.0
always_null Always returns 0.0.0.0 or ::0 for every name in the zone. Like \%redirect with zero data for A and AAAA. Ignores local data in the zone. Used for some block lists. NINDENT NDENT 7.0
noview Breaks out of that view and moves towards the global local zones for answer to the query. If the \%view-first is no, it\(aqll resolve normally. If \%view-first is enabled, it\(aqll break perform that step and check the global answers. For when the view has view specific overrides but some zone has to be answered from global local zone contents. NINDENT NDENT 7.0
nodefault Used to turn off default contents for AS112 zones. The other types also turn off default contents for the zone. The \%nodefault option has no other effect than turning off default contents for the given zone. Use \%nodefault if you use exactly that zone, if you want to use a subzone, use \%transparent. NINDENT The default zones are localhost, reverse 127.0.0.1 and ::1, the home.arpa, resolver.arpa, service.arpa, onion, test, invalid and the AS112 zones. The AS112 zones are reverse DNS zones for private use and reserved IP addresses for which the servers on the internet cannot provide correct answers. They are configured by default to give NXDOMAIN (no reverse information) answers. The defaults can be turned off by specifying your own \%local-zone of that name, or using the \%nodefault type. Below is a list of the default zone contents. NDENT 7.0
localhost The IPv4 and IPv6 localhost information is given. NS and SOA records are provided for completeness and to satisfy some DNS update tools. Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dqlocalhost.\(dq redirect local-data: \(dqlocalhost. 10800 IN NS localhost.\(dq local-data: \(dqlocalhost. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dq local-data: \(dqlocalhost. 10800 IN A 127.0.0.1\(dq local-data: \(dqlocalhost. 10800 IN AAAA ::1\(dqNINDENT NINDENT NINDENT NDENT 7.0
reverse IPv4 loopback Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dq127.in-addr.arpa.\(dq static local-data: \(dq127.in-addr.arpa. 10800 IN NS localhost.\(dq local-data: \(dq127.in-addr.arpa. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dq local-data: \(dq1.0.0.127.in-addr.arpa. 10800 IN PTR localhost.\(dqNINDENT NINDENT NINDENT NDENT 7.0
reverse IPv6 loopback Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dq1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa.\(dq static local-data: \(dq1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN NS localhost.\(dq local-data: \(dq1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dq local-data: \(dq1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN PTR localhost.\(dqNINDENT NINDENT NINDENT NDENT 7.0
home.arpa (\%RFC 8375) Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dqhome.arpa.\(dq static local-data: \(dqhome.arpa. 10800 IN NS localhost.\(dq local-data: \(dqhome.arpa. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dqNINDENT NINDENT NINDENT NDENT 7.0
resolver.arpa (\%RFC 9462) Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dqresolver.arpa.\(dq static local-data: \(dqresolver.arpa. 10800 IN NS localhost.\(dq local-data: \(dqresolver.arpa. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dqNINDENT NINDENT NINDENT NDENT 7.0
service.arpa (draft-ietf-dnssd-srp-25) Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dqservice.arpa.\(dq static local-data: \(dqservice.arpa. 10800 IN NS localhost.\(dq local-data: \(dqservice.arpa. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dqNINDENT NINDENT NINDENT NDENT 7.0
onion (\%RFC 7686) Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dqonion.\(dq static local-data: \(dqonion. 10800 IN NS localhost.\(dq local-data: \(dqonion. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dqNINDENT NINDENT NINDENT NDENT 7.0
test (\%RFC 6761) Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dqtest.\(dq static local-data: \(dqtest. 10800 IN NS localhost.\(dq local-data: \(dqtest. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dqNINDENT NINDENT NINDENT NDENT 7.0
invalid (\%RFC 6761) Default content: NDENT 7.0 NDENT 3.5
local-zone: \(dqinvalid.\(dq static local-data: \(dqinvalid. 10800 IN NS localhost.\(dq local-data: \(dqinvalid. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800\(dqNINDENT NINDENT NINDENT NDENT 7.0
reverse local use zones (\%RFC 1918) Reverse data for zones 10.in-addr.arpa, 16.172.in-addr.arpa to 31.172.in-addr.arpa, 168.192.in-addr.arpa. The \%local-zone is set static and as \%local-data SOA and NS records are provided. NINDENT NDENT 7.0
special-use IPv4 Addresses (\%RFC 3330) Reverse data for zones 0.in-addr.arpa (this), 254.169.in-addr.arpa (link-local), 2.0.192.in-addr.arpa (TEST NET 1), 100.51.198.in-addr.arpa (TEST NET 2), 113.0.203.in-addr.arpa (TEST NET 3), 255.255.255.255.in-addr.arpa (broadcast). And from 64.100.in-addr.arpa to 127.100.in-addr.arpa (Shared Address Space). NINDENT NDENT 7.0
reverse IPv6 unspecified (\%RFC 4291) Reverse data for zone 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. NINDENT NDENT 7.0
reverse IPv6 Locally Assigned Local Addresses (\%RFC 4193) Reverse data for zone D.F.ip6.arpa. NINDENT NDENT 7.0
reverse IPv6 Link Local Addresses (\%RFC 4291) Reverse data for zones 8.E.F.ip6.arpa to B.E.F.ip6.arpa. NINDENT NDENT 7.0
reverse IPv6 Example Prefix Reverse data for zone 8.B.D.0.1.0.0.2.ip6.arpa. This zone is used for tutorials and examples. You can remove the block on this zone with: NDENT 7.0 NDENT 3.5
local-zone: 8.B.D.0.1.0.0.2.ip6.arpa. nodefaultNINDENT NINDENT NINDENT You can also selectively unblock a part of the zone by making that part transparent with a \%local-zone statement. This also works with the other default zones. NINDENT NDENT 0.0
local-data: \(dq<resource record string>\(dq Configure local data, which is served in reply to queries for it. The query has to match exactly unless you configure the \%local-zone as redirect. If not matched exactly, the \%local-zone type determines further processing. If \%local-data is configured that is not a subdomain of a \%local-zone, a \%transparent local-zone is configured. For record types such as TXT, use single quotes, as in: NDENT 7.0 NDENT 3.5
local-data: \(aqexample. TXT \(dqtext\(dq\(aqNINDENT NINDENT NOTE: NDENT 7.0 NDENT 3.5 If you need more complicated authoritative data, with referrals, wildcards, CNAME/DNAME support, or DNSSEC authoritative service, setup a \%stub-zone for it as detailed in the stub zone section below. NINDENT NINDENT NINDENT NDENT 0.0
local-data-ptr: \(dqIPaddr name\(dq Configure local data shorthand for a PTR record with the reversed IPv4 or IPv6 address and the host name. For example \(dq192.0.2.4 www.example.com\(dq. TTL can be inserted like this: \(dq2001:DB8::4 7200 www.example.com\(dq NINDENT NDENT 0.0
local-zone-tag: <zone> <\(dqlist of tags\(dq> Assign tags to local zones. Tagged localzones will only be applied when the used \%access-control element has a matching tag. Tags must be defined in \%define-tag. Enclose list of tags in quotes (\(dq\(dq) and put spaces between tags. When there are multiple tags it checks if the intersection of the list of tags for the query and \%local-zone-tag is non-empty. NINDENT NDENT 0.0
local-zone-override: <zone> <IP netblock> <type> Override the local zone type for queries from addresses matching netblock. Use this localzone type, regardless the type configured for the local zone (both tagged and untagged) and regardless the type configured using \%access-control-tag-action. NINDENT NDENT 0.0
response-ip: <IP-netblock> <action> This requires use of the respip module. If the IP address in an AAAA or A RR in the answer section of a response matches the specified IP netblock, the specified action will apply. <action> has generally the same semantics as that for \%access-control-tag-action, but there are some exceptions. Actions for \%response-ip are different from those for \%local-zone in that in case of the former there is no point of such conditions as \(dqthe query matches it but there is no local data\(dq. Because of this difference, the semantics of \%response-ip actions are modified or simplified as follows: The static, refuse, transparent, typetransparent, and nodefault actions are invalid for response-ip. Using any of these will cause the configuration to be rejected as faulty. The deny action is non-conditional, i.e. it always results in dropping the corresponding query. The resolution result before applying the deny action is still cached and can be used for other queries. NINDENT NDENT 0.0
response-ip-data: <IP-netblock> <\(dqresource record string\(dq> This requires use of the respip module. This specifies the action data for \%response-ip with action being to redirect as specified by <\(dqresource record string\(dq>. <\(dqResource record string\(dq> is similar to that of \%access-control-tag-action, but it must be of either AAAA, A or CNAME types. If the <IP-netblock> is an IPv6/IPv4 prefix, the record must be AAAA/A respectively, unless it is a CNAME (which can be used for both versions of IP netblocks). If it is CNAME there must not be more than one \%response-ip-data for the same <IP-netblock>. Also, CNAME and other types of records must not coexist for the same <IP-netblock>, following the normal rules for CNAME records. The textual domain name for the CNAME does not have to be explicitly terminated with a dot (\(dq.\(dq); the root name is assumed to be the origin for the name. NINDENT NDENT 0.0
response-ip-tag: <IP-netblock> <\(dqlist of tags\(dq> This requires use of the respip module. Assign tags to response <IP-netblock>. If the IP address in an AAAA or A RR in the answer section of a response matches the specified <IP-netblock>, the specified tags are assigned to the IP address. Then, if an \%access-control-tag is defined for the client and it includes one of the tags for the response IP, the corresponding \%access-control-tag-action will apply. Tag matching rule is the same as that for \%access-control-tag and \%local-zone. Unlike \%local-zone-tag, \%response-ip-tag can be defined for an <IP-netblock> even if no \%response-ip is defined for that netblock. If multiple \%response-ip-tag options are specified for the same <IP-netblock> in different statements, all but the first will be ignored. However, this will not be flagged as a configuration error, but the result is probably not what was intended. Actions specified in an \%access-control-tag-action that has a matching tag with \%response-ip-tag can be those that are \(dqinvalid\(dq for \%response-ip listed above, since \%access-control-tag-action can be shared with local zones. For these actions, if they behave differently depending on whether local data exists or not in case of local zones, the behavior for \%response-ip-data will generally result in NOERROR/NODATA instead of NXDOMAIN, since the \%response-ip data are inherently type specific, and non-existence of data does not indicate anything about the existence or non-existence of the qname itself. For example, if the matching tag action is static but there is no data for the corresponding \%response-ip configuration, then the result will be NOERROR/NODATA. The only case where NXDOMAIN is returned is when an \%always_nxdomain action applies. NINDENT NDENT 0.0
ratelimit: <number or 0> Enable ratelimiting of queries sent to nameserver for performing recursion. 0 disables the feature. This option is experimental at this time. The ratelimit is in queries per second that are allowed. More queries are turned away with an error (SERVFAIL). Cached responses are not ratelimited by this setting. This stops recursive floods, eg. random query names, but not spoofed reflection floods. The zone of the query is determined by examining the nameservers for it, the zone name is used to keep track of the rate. For example, 1000 may be a suitable value to stop the server from being overloaded with random names, and keeps unbound from sending traffic to the nameservers for those zones. NOTE: NDENT 7.0 NDENT 3.5 Configured forwarders are excluded from ratelimiting. NINDENT NINDENT Default: 0 NINDENT NDENT 0.0
ratelimit-size: <memory size> Give the size of the data structure in which the current ongoing rates are kept track in. In bytes or use m(mega), k(kilo), g(giga). The ratelimit structure is small, so this data structure likely does not need to be large. Default: 4m NINDENT NDENT 0.0
ratelimit-slabs: <number> Number of slabs in the ratelimit tracking data structure. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT NDENT 0.0
ratelimit-factor: <number> Set the amount of queries to rate limit when the limit is exceeded. If set to 0, all queries are dropped for domains where the limit is exceeded. If set to another value, 1 in that number is allowed through to complete. Default is 10, allowing 1/10 traffic to flow normally. This can make ordinary queries complete (if repeatedly queried for), and enter the cache, whilst also mitigating the traffic flow by the factor given. Default: 10 NINDENT NDENT 0.0
ratelimit-backoff: <yes or no> If enabled, the ratelimit is treated as a hard failure instead of the default maximum allowed constant rate. When the limit is reached, traffic is ratelimited and demand continues to be kept track of for a 2 second rate window. No traffic is allowed, except for \%ratelimit-factor, until demand decreases below the configured ratelimit for a 2 second rate window. Useful to set \%ratelimit to a suspicious rate to aggressively limit unusually high traffic. Default: no NINDENT NDENT 0.0
ratelimit-for-domain: <domain> <number qps or 0> Override the global \%ratelimit for an exact match domain name with the listed number. You can give this for any number of names. For example, for a top-level-domain you may want to have a higher limit than other names. A value of 0 will disable ratelimiting for that domain. NINDENT NDENT 0.0
ratelimit-below-domain: <domain> <number qps or 0> Override the global \%ratelimit for a domain name that ends in this name. You can give this multiple times, it then describes different settings in different parts of the namespace. The closest matching suffix is used to determine the qps limit. The rate for the exact matching domain name is not changed, use \%ratelimit-for-domain to set that, you might want to use different settings for a top-level-domain and subdomains. A value of 0 will disable ratelimiting for domain names that end in this name. NINDENT NDENT 0.0
ip-ratelimit: <number or 0> Enable global ratelimiting of queries accepted per ip address. This option is experimental at this time. The ratelimit is in queries per second that are allowed. More queries are completely dropped and will not receive a reply, SERVFAIL or otherwise. IP ratelimiting happens before looking in the cache. This may be useful for mitigating amplification attacks. Clients with a valid DNS Cookie will bypass the ratelimit. If a ratelimit for such clients is still needed, \%ip-ratelimit-cookie can be used instead. Default: 0 (disabled) NINDENT NDENT 0.0
ip-ratelimit-cookie: <number or 0> Enable global ratelimiting of queries accepted per IP address with a valid DNS Cookie. This option is experimental at this time. The ratelimit is in queries per second that are allowed. More queries are completely dropped and will not receive a reply, SERVFAIL or otherwise. IP ratelimiting happens before looking in the cache. This option could be useful in combination with \%allow_cookie, in an attempt to mitigate other amplification attacks than UDP reflections (e.g., attacks targeting Unbound itself) which are already handled with DNS Cookies. If used, the value is suggested to be higher than \%ip-ratelimit e.g., tenfold. Default: 0 (disabled) NINDENT NDENT 0.0
ip-ratelimit-size: <memory size> Give the size of the data structure in which the current ongoing rates are kept track in. In bytes or use m(mega), k(kilo), g(giga). The IP ratelimit structure is small, so this data structure likely does not need to be large. Default: 4m NINDENT NDENT 0.0
ip-ratelimit-slabs: <number> Number of slabs in the ip ratelimit tracking data structure. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT NDENT 0.0
ip-ratelimit-factor: <number> Set the amount of queries to rate limit when the limit is exceeded. If set to 0, all queries are dropped for addresses where the limit is exceeded. If set to another value, 1 in that number is allowed through to complete. Default is 10, allowing 1/10 traffic to flow normally. This can make ordinary queries complete (if repeatedly queried for), and enter the cache, whilst also mitigating the traffic flow by the factor given. Default: 10 NINDENT NDENT 0.0
ip-ratelimit-backoff: <yes or no> If enabled, the rate limit is treated as a hard failure instead of the default maximum allowed constant rate. When the limit is reached, traffic is ratelimited and demand continues to be kept track of for a 2 second rate window. No traffic is allowed, except for \%ip-ratelimit-factor, until demand decreases below the configured ratelimit for a 2 second rate window. Useful to set \%ip-ratelimit to a suspicious rate to aggressively limit unusually high traffic. Default: no NINDENT NDENT 0.0
outbound-msg-retry: <number> The number of retries, per upstream nameserver in a delegation, that Unbound will attempt in case a throwaway response is received. No response (timeout) contributes to the retry counter. If a forward/stub zone is used, this is the number of retries per nameserver in the zone. Default: 5 NINDENT NDENT 0.0
max-sent-count: <number> Hard limit on the number of outgoing queries Unbound will make while resolving a name, making sure large NS sets do not loop. Results in SERVFAIL when reached. It resets on query restarts (e.g., CNAME) and referrals. Default: 32 NINDENT NDENT 0.0
max-query-restarts: <number> Hard limit on the number of times Unbound is allowed to restart a query upon encountering a CNAME record. Results in SERVFAIL when reached. Changing this value needs caution as it can allow long CNAME chains to be accepted, where Unbound needs to verify (resolve) each link individually. Default: 11 NINDENT NDENT 0.0
iter-scrub-ns: <number> Limit on the number of NS records allowed in an rrset of type NS, from the iterator scrubber. This protects the internals of the resolver from overly large NS sets. Default: 20 NINDENT NDENT 0.0
iter-scrub-cname: <number> Limit on the number of CNAME, DNAME records in an answer, from the iterator scrubber. This protects the internals of the resolver from overly long indirection chains. Clips off the remainder of the reply packet at that point. Default: 11 NINDENT NDENT 0.0
max-global-quota: <number> Limit on the number of upstream queries sent out for an incoming query and its subqueries from recursion. It is not reset during the resolution. When it is exceeded the query is failed and the lookup process stops. Default: 200 NINDENT NDENT 0.0
iter-scrub-promiscuous: <yes or no> Should the iterator scrubber remove promiscuous NS from positive answers. This protects against poisonous contents, that could affect names in the same zone as a spoofed packet. Default: yes NINDENT NDENT 0.0
fast-server-permil: <number> Specify how many times out of 1000 to pick from the set of fastest servers. 0 turns the feature off. A value of 900 would pick from the fastest servers 90 percent of the time, and would perform normal exploration of random servers for the remaining time. When \%prefetch is enabled (or \%serve-expired), such prefetches are not sped up, because there is no one waiting for it, and it presents a good moment to perform server exploration. The \%fast-server-num option can be used to specify the size of the fastest servers set. Default: 0 NINDENT NDENT 0.0
fast-server-num: <number> Set the number of servers that should be used for fast server selection. Only use the fastest specified number of servers with the \%fast-server-permil option, that turns this on or off. Default: 3 NINDENT NDENT 0.0
answer-cookie: <yes or no> If enabled, Unbound will answer to requests containing DNS Cookies as specified in RFC 7873 and RFC 9018. Default: no NINDENT NDENT 0.0
cookie-secret: \(dq<128 bit hex string>\(dq Server\(aqs secret for DNS Cookie generation. Useful to explicitly set for servers in an anycast deployment that need to share the secret in order to verify each other\(aqs Server Cookies. An example hex string would be \(dq000102030405060708090a0b0c0d0e0f\(dq. NOTE: NDENT 7.0 NDENT 3.5 This option is ignored if a \%cookie-secret-file is present. In that case the secrets from that file are used in DNS Cookie calculations. NINDENT NINDENT Default: 128 bits random secret generated at startup time NINDENT NDENT 0.0
cookie-secret-file: <filename> File from which the secrets are read used in DNS Cookie calculations. When this file exists, the secrets in this file are used and the secret specified by the \%cookie-secret option is ignored. Enable it by setting a filename, like \(dq/usr/local/etc/unbound_cookiesecrets.txt\(dq. The content of this file must be manipulated with the \%add_cookie_secret, \%drop_cookie_secret and \%activate_cookie_secret commands to the \%unbound-control(8) tool. Please see that manpage on how to perform a safe cookie secret rollover. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
edns-client-string: <IP netblock> <string> Include an EDNS0 option containing configured ASCII string in queries with destination address matching the configured <IP netblock>. This configuration option can be used multiple times. The most specific match will be used. NINDENT NDENT 0.0
edns-client-string-opcode: <opcode> EDNS0 option code for the \%edns-client-string option, from 0 to 65535. A value from the \(aqReserved for Local/Experimental\(aq range (65001-65534) should be used. Default: 65001 NINDENT NDENT 0.0
ede: <yes or no> If enabled, Unbound will respond with Extended DNS Error codes (\%RFC 8914). These EDEs provide additional information with a response mainly for, but not limited to, DNS and DNSSEC errors. When the \%val-log-level option is also set to 2, responses with Extended DNS Errors concerning DNSSEC failures will also contain a descriptive text message about the reason for the failure. Default: no NINDENT NDENT 0.0
ede-serve-expired: <yes or no> If enabled, Unbound will attach an Extended DNS Error (\%RFC 8914) Code 3 - Stale Answer as EDNS0 option to the expired response. NOTE: NDENT 7.0 NDENT 3.5 \%ede: yes needs to be set as well for this to work. NINDENT NINDENT Default: no NINDENT NDENT 0.0
dns-error-reporting: <yes or no> If enabled, Unbound will send DNS Error Reports (\%RFC 9567). The name servers need to express support by attaching the Report-Channel EDNS0 option on their replies specifying the reporting agent for the zone. Any errors encountered during resolution that would result in Unbound generating an Extended DNS Error (\%RFC 8914) will be reported to the zone\(aqs reporting agent. The \%ede option does not need to be enabled for this to work. It is advised that the \%qname-minimisation option is also enabled to increase privacy on the outgoing reports. Default: no NINDENT
control-enable: <yes or no> The option is used to enable remote control. If turned off, the server does not listen for control commands. Default: no NINDENT NDENT 0.0
control-interface: <IP address or interface name or path> Give IPv4 or IPv6 addresses or local socket path to listen on for control commands. If an interface name is used instead of an IP address, the list of IP addresses on that interface are used. By default localhost (127.0.0.1 and ::1) is listened to. Use 0.0.0.0 and ::0 to listen to all interfaces. If you change this and permissions have been dropped, you must restart the server for the change to take effect. If you set it to an absolute path, a unix domain socket is used. This socket does not use the certificates and keys, so those files need not be present. To restrict access, Unbound sets permissions on the file to the user and group that is configured, the access bits are set to allow the group members to access the control socket file. Put users that need to access the socket in the that group. To restrict access further, create a directory to put the control socket in and restrict access to that directory. NINDENT NDENT 0.0
control-port: <port number> The port number to listen on for IPv4 or IPv6 control interfaces. NOTE: NDENT 7.0 NDENT 3.5 If you change this and permissions have been dropped, you must restart the server for the change to take effect. NINDENT NINDENT Default: 8953 NINDENT NDENT 0.0
control-use-cert: <yes or no> For localhost \%control-interface you can disable the use of TLS by setting this option to \(dqno\(dq. For local sockets, TLS is disabled and the value of this option is ignored. Default: yes NINDENT NDENT 0.0
server-key-file: <private key file> Path to the server private key. This file is generated by the \%unbound-control-setup(8) utility. This file is used by the Unbound server, but not by \%unbound-control(8). Default: unbound_server.key NINDENT NDENT 0.0
server-cert-file: <certificate file.pem> Path to the server self signed certificate. This file is generated by the \%unbound-control-setup(8) utility. This file is used by the Unbound server, and also by \%unbound-control(8). Default: unbound_server.pem NINDENT NDENT 0.0
control-key-file: <private key file> Path to the control client private key. This file is generated by the \%unbound-control-setup(8) utility. This file is used by \%unbound-control(8). Default: unbound_control.key NINDENT NDENT 0.0
control-cert-file: <certificate file.pem> Path to the control client certificate. This certificate has to be signed with the server certificate. This file is generated by the \%unbound-control-setup(8) utility. This file is used by \%unbound-control(8). Default: unbound_control.pem NINDENT
stub-addr: <ip address of host[@port]>NINDENT NINDENT The Unbound resolver can then access the data, without referring to the public internet for it. This setup allows DNSSEC signed zones to be served by that authoritative server, in which case a trusted key entry with the public key can be put in config, so that Unbound can validate the data and set the AD bit on replies for the private zone (authoritative servers do not set the AD bit). This setup makes Unbound capable of answering queries for the private zone, and can even set the AD bit (\(aqauthentic\(aq), but the AA (\(aqauthoritative\(aq) bit is not set on these replies. Consider adding \%server statements for \%domain-insecure and for \%local-zone: <name> nodefault for the zone if it is a locally served zone. The insecure clause stops DNSSEC from invalidating the zone. The \%local-zone: nodefault (or \%transparent) clause makes the (reverse-) zone bypass Unbound\(aqs filtering of \%RFC 1918 zones. NDENT 0.0
name: <domain name> Name of the stub zone. This is the full domain name of the zone. NINDENT NDENT 0.0
stub-host: <domain name> Name of stub zone nameserver. Is itself resolved before it is used. To use a non-default port for DNS communication append \(aq@\(aq with the port number. If TLS is enabled, then you can append a \(aq#\(aq and a name, then it\(aqll check the TLS authentication certificates with that name. If you combine the \(aq@\(aq and \(aq#\(aq, the \(aq@\(aq comes first. If only \(aq#\(aq is used the default port is the configured \%tls-port. NINDENT NDENT 0.0
stub-addr: <IP address> IP address of stub zone nameserver. Can be IPv4 or IPv6. To use a non-default port for DNS communication append \(aq@\(aq with the port number. If TLS is enabled, then you can append a \(aq#\(aq and a name, then it\(aqll check the tls authentication certificates with that name. If you combine the \(aq@\(aq and \(aq#\(aq, the \(aq@\(aq comes first. If only \(aq#\(aq is used the default port is the configured \%tls-port. NINDENT NDENT 0.0
stub-prime: <yes or no> If enabled it performs NS set priming, which is similar to root hints, where it starts using the list of nameservers currently published by the zone. Thus, if the hint list is slightly outdated, the resolver picks up a correct list online. Default: no NINDENT NDENT 0.0
stub-first: <yes or no> If enabled, a query is attempted without the stub clause if it fails. The data could not be retrieved and would have caused SERVFAIL because the servers are unreachable, instead it is tried without this clause. Default: no NINDENT NDENT 0.0
stub-tls-upstream: <yes or no> Enabled or disable whether the queries to this stub use TLS for transport. Default: no NINDENT NDENT 0.0
stub-ssl-upstream: <yes or no> Alternate syntax for \%stub-tls-upstream. NINDENT NDENT 0.0
stub-tcp-upstream: <yes or no> If it is set to \(dqyes\(dq then upstream queries use TCP only for transport regardless of global flag \%tcp-upstream. Default: no NINDENT NDENT 0.0
stub-no-cache: <yes or no> If enabled, data inside the stub is not cached. This is useful when you want immediate changes to be visible. Default: no NINDENT
name: <domain name> Name of the forward zone. This is the full domain name of the zone. NINDENT NDENT 0.0
forward-host: <domain name> Name of server to forward to. Is itself resolved before it is used. To use a non-default port for DNS communication append \(aq@\(aq with the port number. If TLS is enabled, then you can append a \(aq#\(aq and a name, then it\(aqll check the TLS authentication certificates with that name. If you combine the \(aq@\(aq and \(aq#\(aq, the \(aq@\(aq comes first. If only \(aq#\(aq is used the default port is the configured \%tls-port. NINDENT NDENT 0.0
forward-addr: <IP address> IP address of server to forward to. Can be IPv4 or IPv6. To use a non-default port for DNS communication append \(aq@\(aq with the port number. If TLS is enabled, then you can append a \(aq#\(aq and a name, then it\(aqll check the tls authentication certificates with that name. If you combine the \(aq@\(aq and \(aq#\(aq, the \(aq@\(aq comes first. If only \(aq#\(aq is used the default port is the configured \%tls-port. At high verbosity it logs the TLS certificate, with TLS enabled. If you leave out the \(aq#\(aq and auth name from the \%forward-addr, any name is accepted. The cert must also match a CA from the \%tls-cert-bundle. NINDENT NDENT 0.0
forward-first: <yes or no> If a forwarded query is met with a SERVFAIL error, and this option is enabled, Unbound will fall back to normal recursive resolution for this query as if no query forwarding had been specified. Default: no NINDENT NDENT 0.0
forward-tls-upstream: <yes or no> Enabled or disable whether the queries to this forwarder use TLS for transport. If you enable this, also configure a \%tls-cert-bundle or use \%tls-win-cert to load CA certs, otherwise the connections cannot be authenticated. Default: no NINDENT NDENT 0.0
forward-ssl-upstream: <yes or no> Alternate syntax for \%forward-tls-upstream. NINDENT NDENT 0.0
forward-tcp-upstream: <yes or no> If it is set to \(dqyes\(dq then upstream queries use TCP only for transport regardless of global flag \%tcp-upstream. Default: no NINDENT NDENT 0.0
forward-no-cache: <yes or no> If enabled, data inside the forward is not cached. This is useful when you want immediate changes to be visible. Default: no NINDENT
name: <zone name> Name of the authority zone. NINDENT NDENT 0.0
primary: <IP address or host name> Where to download a copy of the zone from, with AXFR and IXFR. Multiple primaries can be specified. They are all tried if one fails. To use a non-default port for DNS communication append \(aq@\(aq with the port number. You can append a \(aq#\(aq and a name, then AXFR over TLS can be used and the TLS authentication certificates will be checked with that name. If you combine the \(aq@\(aq and \(aq#\(aq, the \(aq@\(aq comes first. If you point it at another Unbound instance, it would not work because that does not support AXFR/IXFR for the zone, but if you used \%url to download the zonefile as a text file from a webserver that would work. If you specify the hostname, you cannot use the domain from the zonefile, because it may not have that when retrieving that data, instead use a plain IP address to avoid a circular dependency on retrieving that IP address. NINDENT NDENT 0.0
master: <IP address or host name> Alternate syntax for \%primary. NINDENT NDENT 0.0
url: <URL to zone file> Where to download a zonefile for the zone. With HTTP or HTTPS. An example for the url is: NDENT 7.0 NDENT 3.5
http://www.example.com/example.org.zoneNINDENT NINDENT Multiple url statements can be given, they are tried in turn. If only urls are given the SOA refresh timer is used to wait for making new downloads. If also primaries are listed, the primaries are first probed with UDP SOA queries to see if the SOA serial number has changed, reducing the number of downloads. If none of the urls work, the primaries are tried with IXFR and AXFR. For HTTPS, the \%tls-cert-bundle and the hostname from the url are used to authenticate the connection. If you specify a hostname in the URL, you cannot use the domain from the zonefile, because it may not have that when retrieving that data, instead use a plain IP address to avoid a circular dependency on retrieving that IP address. Avoid dependencies on name lookups by using a notation like \(dqhttp://192.0.2.1/unbound-primaries/example.com.zone\(dq, with an explicit IP address. NINDENT NDENT 0.0
allow-notify: <IP address or host name or netblockIP/prefix> With \%allow-notify you can specify additional sources of notifies. When notified, the server attempts to first probe and then zone transfer. If the notify is from a primary, it first attempts that primary. Otherwise other primaries are attempted. If there are no primaries, but only urls, the file is downloaded when notified. NOTE: NDENT 7.0 NDENT 3.5 The primaries from \%primary and \%url statements are allowed notify by default. NINDENT NINDENT NINDENT NDENT 0.0
fallback-enabled: <yes or no> If enabled, Unbound falls back to querying the internet as a resolver for this zone when lookups fail. For example for DNSSEC validation failures. Default: no NINDENT NDENT 0.0
for-downstream: <yes or no> If enabled, Unbound serves authority responses to downstream clients for this zone. This option makes Unbound behave, for the queries with names in this zone, like one of the authority servers for that zone. Turn it off if you want Unbound to provide recursion for the zone but have a local copy of zone data. If \%for-downstream: no and \%for-upstream: yes are set, then Unbound will DNSSEC validate the contents of the zone before serving the zone contents to clients and store validation results in the cache. Default: yes NINDENT NDENT 0.0
for-upstream: <yes or no> If enabled, Unbound fetches data from this data collection for answering recursion queries. Instead of sending queries over the internet to the authority servers for this zone, it\(aqll fetch the data directly from the zone data. Turn it on when you want Unbound to provide recursion for downstream clients, and use the zone data as a local copy to speed up lookups. Default: yes NINDENT NDENT 0.0
zonemd-check: <yes or no> Enable this option to check ZONEMD records in the zone. The ZONEMD record is a checksum over the zone data. This includes glue in the zone and data from the zone file, and excludes comments from the zone file. When there is a DNSSEC chain of trust, DNSSEC signatures are checked too. Default: no NINDENT NDENT 0.0
zonemd-reject-absence: <yes or no> Enable this option to reject the absence of the ZONEMD record. Without it, when ZONEMD is not there it is not checked. It is useful to enable for a non-DNSSEC signed zone where the operator wants to require the verification of a ZONEMD, hence a missing ZONEMD is a failure. The action upon failure is controlled by the \%zonemd-permissive-mode option, for log only or also block the zone. Without the option, absence of a ZONEMD is only a failure when the zone is DNSSEC signed, and we have a trust anchor, and the DNSSEC verification of the absence of the ZONEMD fails. With the option enabled, the absence of a ZONEMD is always a failure, also for nonDNSSEC signed zones. Default: no NINDENT NDENT 0.0
zonefile: <filename> The filename where the zone is stored. If not given then no zonefile is used. If the file does not exist or is empty, Unbound will attempt to fetch zone data (eg. from the primary servers). NINDENT
name: <view name> Name of the view. Must be unique. This name is used in the \%access-control-view attribute. NINDENT NDENT 0.0
local-zone: <zone> <type> View specific local zone elements. Has the same types and behaviour as the global \%local-zone elements. When there is at least one local-zone: specified and \%view-first: no is set, the default local-zones will be added to this view. Defaults can be disabled using the nodefault type. When \%view-first: yes is set or when a view does not have a \%local-zone, the global \%local-zone will be used including it\(aqs default zones. NINDENT NDENT 0.0
local-data: \(dq<resource record string>\(dq View specific local data elements. Has the same behaviour as the global \%local-data elements. NINDENT NDENT 0.0
local-data-ptr: \(dqIPaddr name\(dq View specific local-data-ptr elements. Has the same behaviour as the global \%local-data-ptr elements. NINDENT NDENT 0.0
view-first: <yes or no> If enabled, it attempts to use the global \%local-zone and \%local-data if there is no match in the view specific options. Default: no NINDENT
python-script: <python file> The script file to load. Repeat this option for every python module instance added to the \%module-config option. NINDENT
dynlib-file: <dynlib file> The dynamic library file to load. Repeat this option for every dynlib module instance added to the \%module-config option. NINDENT
module-config: \(dqdns64 validator iterator\(dqNINDENT NINDENT and be compiled into the daemon to be enabled. NOTE: NDENT 0.0 NDENT 3.5 These settings go in the \%server: section. NINDENT NINDENT NDENT 0.0
dns64-prefix: <IPv6 prefix> This sets the DNS64 prefix to use to synthesize AAAA records with. It must be /96 or shorter. Default: 64:ff9b::/96 NINDENT NDENT 0.0
dns64-synthall: <yes or no> WARNING: NDENT 7.0 NDENT 3.5 Debugging feature! NINDENT NINDENT If enabled, synthesize all AAAA records despite the presence of actual AAAA records. Default: no NINDENT NDENT 0.0
dns64-ignore-aaaa: <domain name> List domain for which the AAAA records are ignored and the A record is used by DNS64 processing instead. Can be entered multiple times, list a new domain for which it applies, one per line. Applies also to names underneath the name given. NINDENT
do-nat64: <yes or no> Use NAT64 to reach IPv4-only servers. Consider also enabling \%prefer-ip6 to prefer native IPv6 connections to nameservers. Default: no NINDENT NDENT 0.0
nat64-prefix: <IPv6 prefix> Use a specific NAT64 prefix to reach IPv4-only servers. The prefix length must be one of /32, /40, /48, /56, /64 or /96. Default: 64:ff9b::/96 (same as \%dns64-prefix) NINDENT
dnscrypt-enable: <yes or no> Whether or not the dnscrypt config should be enabled. You may define configuration but not activate it. Default: no NINDENT NDENT 0.0
dnscrypt-port: <port number> On which port should dnscrypt should be activated. NOTE: NDENT 7.0 NDENT 3.5 There should be a matching interface option defined in the \%server: section for this port. NINDENT NINDENT NINDENT NDENT 0.0
dnscrypt-provider: <provider name> The provider name to use to distribute certificates. This is of the form: NDENT 7.0 NDENT 3.5
2.dnscrypt-cert.example.com.NINDENT NINDENT IMPORTANT: NDENT 7.0 NDENT 3.5 The name MUST end with a dot. NINDENT NINDENT NINDENT NDENT 0.0
dnscrypt-secret-key: <path to secret key file> Path to the time limited secret key file. This option may be specified multiple times. NINDENT NDENT 0.0
dnscrypt-provider-cert: <path to cert file> Path to the certificate related to the \%dnscrypt-secret-key. This option may be specified multiple times. NINDENT NDENT 0.0
dnscrypt-provider-cert-rotated: <path to cert file> Path to a certificate that we should be able to serve existing connection from but do not want to advertise over \%dnscrypt-provider \(aqs TXT record certs distribution. A typical use case is when rotating certificates, existing clients may still use the client magic from the old cert in their queries until they fetch and update the new cert. Likewise, it would allow one to prime the new cert/key without distributing the new cert yet, this can be useful when using a network of servers using anycast and on which the configuration may not get updated at the exact same time. By priming the cert, the servers can handle both old and new certs traffic while distributing only one. This option may be specified multiple times. NINDENT NDENT 0.0
dnscrypt-shared-secret-cache-size: <memory size> Give the size of the data structure in which the shared secret keys are kept in. In bytes or use m(mega), k(kilo), g(giga). The shared secret cache is used when a same client is making multiple queries using the same public key. It saves a substantial amount of CPU. Default: 4m NINDENT NDENT 0.0
dnscrypt-shared-secret-cache-slabs: <number> Number of slabs in the dnscrypt shared secrets cache. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT NDENT 0.0
dnscrypt-nonce-cache-size: <memory size> Give the size of the data structure in which the client nonces are kept in. In bytes or use m(mega), k(kilo), g(giga). The nonce cache is used to prevent dnscrypt message replaying. Client nonce should be unique for any pair of client pk/server sk. Default: 4m NINDENT NDENT 0.0
dnscrypt-nonce-cache-slabs: <number> Number of slabs in the dnscrypt nonce cache. Slabs reduce lock contention by threads. Must be set to a power of 2. Setting (close) to the number of cpus is a fairly good setting. If left unconfigured, it will be configured automatically to be a power of 2 close to the number of configured threads in multi-threaded environments. Default: (unconfigured) NINDENT
module-config: \(dqsubnetcache validator iterator\(dqNINDENT NINDENT and be compiled into the daemon to be enabled. NOTE: NDENT 0.0 NDENT 3.5 These settings go in the \%server: section. NINDENT NINDENT If the destination address is allowed in the configuration Unbound will add the EDNS0 option to the query containing the relevant part of the client\(aqs address. When an answer contains the ECS option the response and the option are placed in a specialized cache. If the authority indicated no support, the response is stored in the regular cache. Additionally, when a client includes the option in its queries, Unbound will forward the option when sending the query to addresses that are explicitly allowed in the configuration using \%send-client-subnet. The option will always be forwarded, regardless the allowed addresses, when \%client-subnet-always-forward: yes is set. In this case the lookup in the regular cache is skipped. The maximum size of the ECS cache is controlled by \%msg-cache-size in the configuration file. On top of that, for each query only 100 different subnets are allowed to be stored for each address family. Exceeding that number, older entries will be purged from cache. Note that due to the nature of how EDNS Client Subnet works, by segregating the client IP space in order to try and have tailored responses for prefixes of unknown sizes, resolution and cache response performance are impacted as a result. Usage of the subnetcache module should only be enabled in installations that require such functionality where the resolver and the clients belong to different networks. An example of that is an open resolver installation. This module does not interact with the \%serve-expired* and \%prefetch options. NDENT 0.0
send-client-subnet: <IP address> Send client source address to this authority. Append /num to indicate a classless delegation netblock, for example like 10.2.3.4/24 or 2001::11/64. Can be given multiple times. Authorities not listed will not receive edns-subnet information, unless domain in query is specified in \%client-subnet-zone. NINDENT NDENT 0.0
client-subnet-zone: <domain> Send client source address in queries for this domain and its subdomains. Can be given multiple times. Zones not listed will not receive edns-subnet information, unless hosted by authority specified in \%send-client-subnet. NINDENT NDENT 0.0
client-subnet-always-forward: <yes or no> Specify whether the ECS address check (configured using \%send-client-subnet) is applied for all queries, even if the triggering query contains an ECS record, or only for queries for which the ECS record is generated using the querier address (and therefore did not contain ECS data in the client query). If enabled, the address check is skipped when the client query contains an ECS record. And the lookup in the regular cache is skipped. Default: no NINDENT NDENT 0.0
max-client-subnet-ipv6: <number> Specifies the maximum prefix length of the client source address we are willing to expose to third parties for IPv6. Default: 56 NINDENT NDENT 0.0
max-client-subnet-ipv4: <number> Specifies the maximum prefix length of the client source address we are willing to expose to third parties for IPv4. Default: 24 NINDENT NDENT 0.0
min-client-subnet-ipv6: <number> Specifies the minimum prefix length of the IPv6 source mask we are willing to accept in queries. Shorter source masks result in REFUSED answers. Source mask of 0 is always accepted. Default: 0 NINDENT NDENT 0.0
min-client-subnet-ipv4: <number> Specifies the minimum prefix length of the IPv4 source mask we are willing to accept in queries. Shorter source masks result in REFUSED answers. Source mask of 0 is always accepted. Default: 0 NINDENT NDENT 0.0
max-ecs-tree-size-ipv4: <number> Specifies the maximum number of subnets ECS answers kept in the ECS radix tree. This number applies for each qname/qclass/qtype tuple. Default: 100 NINDENT NDENT 0.0
max-ecs-tree-size-ipv6: <number> Specifies the maximum number of subnets ECS answers kept in the ECS radix tree. This number applies for each qname/qclass/qtype tuple. Default: 100 NINDENT
module-config: \(dqipsecmod validator iterator\(dqNINDENT NINDENT and be compiled into Unbound by using --enable-ipsecmod to be enabled. NOTE: NDENT 0.0 NDENT 3.5 These settings go in the \%server: section. NINDENT NINDENT When Unbound receives an A/AAAA query that is not in the cache and finds a valid answer, it will withhold returning the answer and instead will generate an IPSECKEY subquery for the same domain name. If an answer was found, Unbound will call an external hook passing the following arguments: NDENT 0.0
QNAME Domain name of the A/AAAA and IPSECKEY query. In string format.
IPSECKEY TTL TTL of the IPSECKEY RRset.
A/AAAA String of space separated IP addresses present in the A/AAAA RRset. The IP addresses are in string format.
IPSECKEY String of space separated IPSECKEY RDATA present in the IPSECKEY RRset. The IPSECKEY RDATA are in DNS presentation format. NINDENT The A/AAAA answer is then cached and returned to the client. If the external hook was called the TTL changes to ensure it doesn\(aqt surpass \%ipsecmod-max-ttl. The same procedure is also followed when \%prefetch: yes is set, but the A/AAAA answer is given to the client before the hook is called. \%ipsecmod-max-ttl ensures that the A/AAAA answer given from cache is still relevant for opportunistic IPsec. NDENT 0.0
ipsecmod-enabled: <yes or no> Specifies whether the IPsec module is enabled or not. The IPsec module still needs to be defined in the \%module-config directive. This option facilitates turning on/off the module without restarting/reloading Unbound. Default: yes NINDENT NDENT 0.0
ipsecmod-hook: <filename> Specifies the external hook that Unbound will call with system(3). The file can be specified as an absolute/relative path. The file needs the proper permissions to be able to be executed by the same user that runs Unbound. It must be present when the IPsec module is defined in the \%module-config directive. NINDENT NDENT 0.0
ipsecmod-strict: <yes or no> If enabled Unbound requires the external hook to return a success value of 0. Failing to do so Unbound will reply with SERVFAIL. The A/AAAA answer will also not be cached. Default: no NINDENT NDENT 0.0
ipsecmod-max-ttl: <seconds> Time to live maximum for A/AAAA cached records after calling the external hook. Default: 3600 NINDENT NDENT 0.0
ipsecmod-ignore-bogus: <yes or no> Specifies the behaviour of Unbound when the IPSECKEY answer is bogus. If set to yes, the hook will be called and the A/AAAA answer will be returned to the client. If set to no, the hook will not be called and the answer to the A/AAAA query will be SERVFAIL. Mainly used for testing. Default: no NINDENT NDENT 0.0
ipsecmod-allow: <domain> Allow the IPsec module functionality for the domain so that the module logic will be executed. Can be given multiple times, for different domains. If the option is not specified, all domains are treated as being allowed (default). NINDENT NDENT 0.0
ipsecmod-whitelist: <domain> Alternate syntax for \%ipsecmod-allow. NINDENT
module-config: \(dqvalidator cachedb iterator\(dqNINDENT NINDENT and be compiled into the daemon with --enable-cachedb. If this module is enabled and configured, the specified backend database works as a second level cache; when Unbound cannot find an answer to a query in its built-in in-memory cache, it consults the specified backend. If it finds a valid answer in the backend, Unbound uses it to respond to the query without performing iterative DNS resolution. If Unbound cannot even find an answer in the backend, it resolves the query as usual, and stores the answer in the backend. This module interacts with the serve-expired-* options and will reply with expired data if Unbound is configured for that. If Unbound was built with --with-libhiredis on a system that has installed the hiredis C client library of Redis, then the redis backend can be used. This backend communicates with the specified Redis server over a TCP connection to store and retrieve cache data. It can be used as a persistent and/or shared cache backend. NOTE: NDENT 0.0 NDENT 3.5 Unbound never removes data stored in the Redis server, even if some data have expired in terms of DNS TTL or the Redis server has cached too much data; if necessary the Redis server must be configured to limit the cache size, preferably with some kind of least-recently-used eviction policy. NINDENT NINDENT Additionally, the \%redis-expire-records option can be used in order to set the relative DNS TTL of the message as timeout to the Redis records; keep in mind that some additional memory is used per key and that the expire information is stored as absolute Unix timestamps in Redis (computer time must be stable). This backend uses synchronous communication with the Redis server based on the assumption that the communication is stable and sufficiently fast. The thread waiting for a response from the Redis server cannot handle other DNS queries. Although the backend has the ability to reconnect to the server when the connection is closed unexpectedly and there is a configurable timeout in case the server is overly slow or hangs up, these cases are assumed to be very rare. If connection close or timeout happens too often, Unbound will be effectively unusable with this backend. It\(aqs the administrator\(aqs responsibility to make the assumption hold. The cachedb: clause gives custom settings of the cache DB module. NDENT 0.0
backend: <backend name> Specify the backend database name. The default database is the in-memory backend named testframe, which, as the name suggests, is not of any practical use. Depending on the build-time configuration, redis backend may also be used as described above. Default: testframe NINDENT NDENT 0.0
secret-seed: \(dq<secret string>\(dq Specify a seed to calculate a hash value from query information. This value will be used as the key of the corresponding answer for the backend database and can be customized if the hash should not be predictable operationally. If the backend database is shared by multiple Unbound instances, all instances must use the same secret seed. Default: \(dqdefault\(dq NINDENT NDENT 0.0
cachedb-no-store: <yes or no> If the backend should be read from, but not written to. This makes this instance not store dns messages in the backend. But if data is available it is retrieved. Default: no NINDENT NDENT 0.0
cachedb-check-when-serve-expired: <yes or no> If enabled, the cachedb is checked before an expired response is returned. When \%serve-expired is enabled, without \%serve-expired-client-timeout , it then does not immediately respond with an expired response from cache, but instead first checks the cachedb for valid contents, and if so returns it. If the cachedb also has no valid contents, the serve expired response is sent. If also \%serve-expired-client-timeout is enabled, the expired response is delayed until the timeout expires. Unless the lookup succeeds within the timeout. Default: yes NINDENT The following cachedb: options are specific to the redis backend. NDENT 0.0
redis-server-host: <server address or name> The IP (either v6 or v4) address or domain name of the Redis server. In general an IP address should be specified as otherwise Unbound will have to resolve the name of the server every time it establishes a connection to the server. Default: 127.0.0.1 NINDENT NDENT 0.0
redis-server-port: <port number> The TCP port number of the Redis server. Default: 6379 NINDENT NDENT 0.0
redis-server-path: <unix socket path> The unix socket path to connect to the Redis server. Unix sockets may have better throughput than the IP address option. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
redis-server-password: \(dq<password>\(dq The Redis AUTH password to use for the Redis server. Only relevant if Redis is configured for client password authorisation. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
redis-timeout: <msec> The period until when Unbound waits for a response from the Redis server. If this timeout expires Unbound closes the connection, treats it as if the Redis server does not have the requested data, and will try to re-establish a new connection later. Default: 100 NINDENT NDENT 0.0
redis-command-timeout: <msec> The timeout to use for Redis commands, in milliseconds. If 0, it uses the \%redis-timeout value. Default: 0 NINDENT NDENT 0.0
redis-connect-timeout: <msec> The timeout to use for Redis connection set up, in milliseconds. If 0, it uses the \%redis-timeout value. Default: 0 NINDENT NDENT 0.0
redis-expire-records: <yes or no> If Redis record expiration is enabled. If yes, Unbound sets timeout for Redis records so that Redis can evict keys that have expired automatically. If Unbound is configured with \%serve-expired and \%serve-expired-ttl: 0, this option is internally reverted to \(dqno\(dq. NOTE: NDENT 7.0 NDENT 3.5 Redis \(dqSET ... EX\(dq support is required for this option (Redis >= 2.6.12). NINDENT NINDENT Default: no NINDENT NDENT 0.0
redis-logical-db: <logical database index> The logical database in Redis to use. These are databases in the same Redis instance sharing the same configuration and persisted in the same RDB/AOF file. If unsure about using this option, Redis documentation (\%https://redis.io/commands/select/) suggests not to use a single Redis instance for multiple unrelated applications. The default database in Redis is 0 while other logical databases need to be explicitly SELECT\(aqed upon connecting. Default: 0 NINDENT NDENT 0.0
redis-replica-server-host: <server address or name> The IP (either v6 or v4) address or domain name of the Redis server. In general an IP address should be specified as otherwise Unbound will have to resolve the name of the server every time it establishes a connection to the server. This server is treated as a read-only replica server (\%https://redis.io/docs/management/replication/#read-only-replica). If specified, all Redis read commands will go to this replica server, while the write commands will go to the \%redis-server-host. Default: \(dq\(dq (disabled). NINDENT NDENT 0.0
redis-replica-server-port: <port number> The TCP port number of the Redis replica server. Default: 6379 NINDENT NDENT 0.0
redis-replica-server-path: <unix socket path> The unix socket path to connect to the Redis replica server. Unix sockets may have better throughput than the IP address option. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
redis-replica-server-password: \(dq<password>\(dq The Redis AUTH password to use for the Redis server. Only relevant if Redis is configured for client password authorisation. Default: \(dq\(dq (disabled) NINDENT NDENT 0.0
redis-replica-timeout: <msec> The period until when Unbound waits for a response from the Redis replica server. If this timeout expires Unbound closes the connection, treats it as if the Redis server does not have the requested data, and will try to re-establish a new connection later. Default: 100 NINDENT NDENT 0.0
redis-replica-command-timeout: <msec> The timeout to use for Redis replica commands, in milliseconds. If 0, it uses the \%redis-replica-timeout value. Default: 0 NINDENT NDENT 0.0
redis-replica-connect-timeout: <msec> The timeout to use for Redis replica connection set up, in milliseconds. If 0, it uses the \%redis-replica-timeout value. Default: 0 NINDENT NDENT 0.0
redis-replica-logical-db: <logical database index> Same as \%redis-logical-db but for the Redis replica server. Default: 0 NINDENT
dnstap-enable: <yes or no> If dnstap is enabled. If yes, it connects to the DNSTAP server and if any of the dnstap-log-..-messages: options is enabled it sends logs for those messages to the server. Default: no NINDENT NDENT 0.0
dnstap-bidirectional: <yes or no> Use frame streams in bidirectional mode to transfer DNSTAP messages. Default: yes NINDENT NDENT 0.0
dnstap-socket-path: <file name> Sets the unix socket file name for connecting to the server that is listening on that socket. Default: @DNSTAP_SOCKET_PATH@ NINDENT NDENT 0.0
dnstap-ip: <IPaddress[@port]> If \(dq\(dq, the unix socket is used, if set with an IP address (IPv4 or IPv6) that address is used to connect to the server. Default: \(dq\(dq NINDENT NDENT 0.0
dnstap-tls: <yes or no> Set this to use TLS to connect to the server specified in \%dnstap-ip. If set to no, TCP is used to connect to the server. Default: yes NINDENT NDENT 0.0
dnstap-tls-server-name: <name of TLS authentication> The TLS server name to authenticate the server with. Used when \%dnstap-tls: yes is set. If \(dq\(dq it is ignored. Default: \(dq\(dq NINDENT NDENT 0.0
dnstap-tls-cert-bundle: <file name of cert bundle> The pem file with certs to verify the TLS server certificate. If \(dq\(dq the server default cert bundle is used, or the windows cert bundle on windows. Default: \(dq\(dq NINDENT NDENT 0.0
dnstap-tls-client-key-file: <file name> The client key file for TLS client authentication. If \(dq\(dq client authentication is not used. Default: \(dq\(dq NINDENT NDENT 0.0
dnstap-tls-client-cert-file: <file name> The client cert file for TLS client authentication. Default: \(dq\(dq NINDENT NDENT 0.0
dnstap-send-identity: <yes or no> If enabled, the server identity is included in the log messages. Default: no NINDENT NDENT 0.0
dnstap-send-version: <yes or no> If enabled, the server version if included in the log messages. Default: no NINDENT NDENT 0.0
dnstap-identity: <string> The identity to send with messages, if \(dq\(dq the hostname is used. Default: \(dq\(dq NINDENT NDENT 0.0
dnstap-version: <string> The version to send with messages, if \(dq\(dq the package version is used. Default: \(dq\(dq NINDENT NDENT 0.0
dnstap-sample-rate: <number> The sample rate for log of messages, it logs only 1/N messages. With 0 it is disabled. This is useful in a high volume environment, where log functionality would otherwise not be reliable. For example 10 would spend only 1/10th time on logging, and 100 would only spend a hundredth of the time on logging. Default: 0 (disabled) NINDENT NDENT 0.0
dnstap-log-resolver-query-messages: <yes or no> Enable to log resolver query messages. These are messages from Unbound to upstream servers. Default: no NINDENT NDENT 0.0
dnstap-log-resolver-response-messages: <yes or no> Enable to log resolver response messages. These are replies from upstream servers to Unbound. Default: no NINDENT NDENT 0.0
dnstap-log-client-query-messages: <yes or no> Enable to log client query messages. These are client queries to Unbound. Default: no NINDENT NDENT 0.0
dnstap-log-client-response-messages: <yes or no> Enable to log client response messages. These are responses from Unbound to clients. Default: no NINDENT NDENT 0.0
dnstap-log-forwarder-query-messages: <yes or no> Enable to log forwarder query messages. Default: no NINDENT NDENT 0.0
dnstap-log-forwarder-response-messages: <yes or no> Enable to log forwarder response messages. Default: no NINDENT
module-config: \(dqrespip validator iterator\(dqNINDENT NINDENT QNAME, Response IP Address, nsdname, nsip and clientip triggers are supported. Supported actions are: NXDOMAIN, NODATA, PASSTHRU, DROP, Local Data, tcp-only and drop. RPZ QNAME triggers are applied after any \%local-zone and before any \%auth-zone. The RPZ zone is a regular DNS zone formatted with a SOA start record as usual. The items in the zone are entries, that specify what to act on (the trigger) and what to do (the action). The trigger to act on is recorded in the name, the action to do is recorded as the resource record. The names all end in the zone name, so you could type the trigger names without a trailing dot in the zonefile. An example RPZ record, that answers example.com with NXDOMAIN: NDENT 0.0 NDENT 3.5
example.com CNAME .NINDENT NINDENT The triggers are encoded in the name on the left NDENT 0.0 NDENT 3.5
name query name netblock.rpz-client-ip client IP address netblock.rpz-ip response IP address in the answer name.rpz-nsdname nameserver name netblock.rpz-nsip nameserver IP addressNINDENT NINDENT The netblock is written as <netblocklen>.<ip address in reverse>. For IPv6 use \(aqzz\(aq for \(aq::\(aq. Specify individual addresses with scope length of 32 or 128. For example, 24.10.100.51.198.rpz-ip is 198.51.100.10/24 and 32.10.zz.db8.2001.rpz-ip is 2001:db8:0:0:0:0:0:10/32. The actions are specified with the record on the right NDENT 0.0 NDENT 3.5
CNAME . nxdomain reply CNAME *. nodata reply CNAME rpz-passthru. do nothing, allow to continue CNAME rpz-drop. the query is dropped CNAME rpz-tcp-only. answer over TCP A 192.0.2.1 answer with this IP addressNINDENT NINDENT Other records like AAAA, TXT and other CNAMEs (not rpz-..) can also be used to answer queries with that content. The RPZ zones can be configured in the config file with these settings in the rpz: block. NDENT 0.0
name: <zone name> Name of the authority zone. NINDENT NDENT 0.0
primary: <IP address or host name> Where to download a copy of the zone from, with AXFR and IXFR. Multiple primaries can be specified. They are all tried if one fails. To use a non-default port for DNS communication append \(aq@\(aq with the port number. You can append a \(aq#\(aq and a name, then AXFR over TLS can be used and the TLS authentication certificates will be checked with that name. If you combine the \(aq@\(aq and \(aq#\(aq, the \(aq@\(aq comes first. If you point it at another Unbound instance, it would not work because that does not support AXFR/IXFR for the zone, but if you used \%url to download the zonefile as a text file from a webserver that would work. If you specify the hostname, you cannot use the domain from the zonefile, because it may not have that when retrieving that data, instead use a plain IP address to avoid a circular dependency on retrieving that IP address. NINDENT NDENT 0.0
master: <IP address or host name> Alternate syntax for \%primary. NINDENT NDENT 0.0
url: <url to zonefile> Where to download a zonefile for the zone. With HTTP or HTTPS. An example for the url is: NDENT 7.0 NDENT 3.5
http://www.example.com/example.org.zoneNINDENT NINDENT Multiple url statements can be given, they are tried in turn. If only urls are given the SOA refresh timer is used to wait for making new downloads. If also primaries are listed, the primaries are first probed with UDP SOA queries to see if the SOA serial number has changed, reducing the number of downloads. If none of the URLs work, the primaries are tried with IXFR and AXFR. For HTTPS, the \%tls-cert-bundle and the hostname from the url are used to authenticate the connection. NINDENT NDENT 0.0
allow-notify: <IP address or host name or netblockIP/prefix> With \%allow-notify you can specify additional sources of notifies. When notified, the server attempts to first probe and then zone transfer. If the notify is from a primary, it first attempts that primary. Otherwise other primaries are attempted. If there are no primaries, but only urls, the file is downloaded when notified. NOTE: NDENT 7.0 NDENT 3.5 The primaries from \%primary and \%url statements are allowed notify by default. NINDENT NINDENT NINDENT NDENT 0.0
zonefile: <filename> The filename where the zone is stored. If not given then no zonefile is used. If the file does not exist or is empty, Unbound will attempt to fetch zone data (eg. from the primary servers). NINDENT NDENT 0.0
rpz-action-override: <action> Always use this RPZ action for matching triggers from this zone. Possible actions are: nxdomain, nodata, passthru, drop, disabled and cname. NINDENT NDENT 0.0
rpz-cname-override: <domain> The CNAME target domain to use if the cname action is configured for \%rpz-action-override. NINDENT NDENT 0.0
rpz-log: <yes or no> Log all applied RPZ actions for this RPZ zone. Default: no NINDENT NDENT 0.0
rpz-log-name: <name> Specify a string to be part of the log line, for easy referencing. NINDENT NDENT 0.0
rpz-signal-nxdomain-ra: <yes or no> Signal when a query is blocked by the RPZ with NXDOMAIN with an unset RA flag. This allows certain clients, like dnsmasq, to infer that the domain is externally blocked. Default: no NINDENT NDENT 0.0
for-downstream: <yes or no> If enabled the zone is authoritatively answered for and queries for the RPZ zone information are answered to downstream clients. This is useful for monitoring scripts, that can then access the SOA information to check if the RPZ information is up to date. Default: no NINDENT NDENT 0.0
tags: \(dq<list of tags>\(dq Limit the policies from this RPZ clause to clients with a matching tag. Tags need to be defined in \%define-tag and can be assigned to client addresses using \%access-control-tag or \%interface-tag. Enclose list of tags in quotes (\(dq\(dq) and put spaces between tags. If no tags are specified the policies from this clause will be applied for all clients. NINDENT
# example settings that reduce memory usage server: num-threads: 1 outgoing-num-tcp: 1 # this limits TCP service, uses less buffers. incoming-num-tcp: 1 outgoing-range: 60 # uses less memory, but less performance. msg-buffer-size: 8192 # note this limits service, \(aqno huge stuff\(aq. msg-cache-size: 100k msg-cache-slabs: 1 rrset-cache-size: 100k rrset-cache-slabs: 1 infra-cache-numhosts: 200 infra-cache-slabs: 1 key-cache-size: 100k key-cache-slabs: 1 neg-cache-size: 10k num-queries-per-thread: 30 target-fetch-policy: \(dq2 1 0 0 0 0\(dq harden-large-queries: \(dqyes\(dq harden-short-bufsize: \(dqyes\(dqNINDENT NINDENT
@UNBOUND_RUN_DIR@ default Unbound working directory.
@UNBOUND_CHROOT_DIR@ default chroot(2) location.
@ub_conf_file@ Unbound configuration file.
@UNBOUND_PIDFILE@ default Unbound pidfile with process ID of the running daemon.
unbound.log Unbound log file. Default is to log to syslog(3). NINDENT
.