.\" .\" Copyright (C) 2022 Alexander Chernikov . .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .Dd November 1, 2022 .Dt RTNETLINK 4 .Os .Sh NAME .Nm RTNetlink .Nd Network configuration-specific Netlink family .Sh SYNOPSIS .In netlink/netlink.h .In netlink/netlink_route.h .Ft int .Fn socket AF_NETLINK SOCK_RAW NETLINK_ROUTE .Sh DESCRIPTION The .Dv NETLINK_ROUTE family aims to be the primary configuration mechanism for all network-related tasks. Currently it supports configuring interfaces, interface addresses, routes, nexthops and arp/ndp neighbors. .Sh ROUTES All route configuration messages share the common header: .Bd -literal struct rtmsg { unsigned char rtm_family; /* address family */ unsigned char rtm_dst_len; /* Prefix length */ unsigned char rtm_src_len; /* Deprecated, set to 0 */ unsigned char rtm_tos; /* Type of service (not used) */ unsigned char rtm_table; /* deprecated, set to 0 */ unsigned char rtm_protocol; /* Routing protocol id (RTPROT_) */ unsigned char rtm_scope; /* Route distance (RT_SCOPE_) */ unsigned char rtm_type; /* Route type (RTN_) */ unsigned rtm_flags; /* Route flags (not supported) */ }; .Ed .Pp The .Va rtm_family specifies the route family to be operated on. Currently, .Dv AF_INET6 and .Dv AF_INET are the only supported families. The route prefix length is stored in .Va rtm_dst_len . The caller should set the originator identity (one of the .Dv RTPROT_ values) in .Va rtm_protocol . It is useful for users and for the application itself, allowing for easy identification of self-originated routes. The route scope has to be set via .Va rtm_scope field. The supported values are: .Bd -literal -offset indent -compact RT_SCOPE_UNIVERSE Global scope RT_SCOPE_LINK Link scope .Ed .Pp Route type needs to be set. The defined values are: .Bd -literal -offset indent -compact RTN_UNICAST Unicast route RTN_MULTICAST Multicast route RTN_BLACKHOLE Drops traffic towards destination RTN_PROHIBIT Drops traffic and sends reject .Ed .Pp The following messages are supported: .Ss RTM_NEWROUTE Adds a new route. All NL flags are supported. Extending a multipath route requires NLM_F_APPEND flag. .Ss RTM_DELROUTE Tries to delete a route. The route is specified using a combination of .Dv RTA_DST TLV and .Va rtm_dst_len . .Ss RTM_GETROUTE Fetches a single route or all routes in the current VNET, depending on the .Dv NLM_F_DUMP flag. Each route is reported as .Dv RTM_NEWROUTE message. The following filters are recognised by the kernel: .Pp .Bd -literal -offset indent -compact rtm_family required family or AF_UNSPEC RTA_TABLE fib number or RT_TABLE_UNSPEC to return all fibs .Ed .Ss TLVs .Bl -tag -width indent .It Dv RTA_DST (binary) IPv4/IPv6 address, depending on the .Va rtm_family . .It Dv RTA_OIF (uint32_t) transmit interface index. .It Dv RTA_GATEWAY (binary) IPv4/IPv6 gateway address, depending on the .Va rtm_family . .It Dv RTA_METRICS (nested) Container attribute, listing route properties. The only supported sub-attribute is .Dv RTAX_MTU , which stores path MTU as uint32_t. .It Dv RTA_MULTIPATH This attribute contains multipath route nexthops with their weights. These nexthops are represented as a sequence of .Va rtnexthop structures, each followed by .Dv RTA_GATEWAY or .Dv RTA_VIA attributes. .Bd -literal struct rtnexthop { unsigned short rtnh_len; unsigned char rtnh_flags; unsigned char rtnh_hops; /* nexthop weight */ int rtnh_ifindex; }; .Ed .Pp The .Va rtnh_len field specifies the total nexthop info length, including both .Va struct rtnexthop and the following TLVs. The .Va rtnh_hops field stores relative nexthop weight, used for load balancing between group members. The .Va rtnh_ifindex field contains the index of the transmit interface. .Pp The following TLVs can follow the structure: .Bd -literal -offset indent -compact RTA_GATEWAY IPv4/IPv6 nexthop address of the gateway RTA_VIA IPv6 nexthop address for IPv4 route RTA_KNH_ID Kernel-specific index of the nexthop .Ed .It Dv RTA_KNH_ID (uint32_t) (FreeBSD-specific) Auto-allocated kernel index of the nexthop. .It Dv RTA_RTFLAGS (uint32_t) (FreeBSD-specific) rtsock route flags. .It Dv RTA_TABLE (uint32_t) Fib number of the route. Default route table is .Dv RT_TABLE_MAIN . To explicitly specify "all tables" one needs to set the value to .Dv RT_TABLE_UNSPEC . .It Dv RTA_EXPIRES (uint32_t) seconds till path expiration. .It Dv RTA_NH_ID (uint32_t) useland nexthop or nexthop group index. .El .Ss Groups The following groups are defined: .Bd -literal -offset indent -compact RTNLGRP_IPV4_ROUTE Notifies on IPv4 route arrival/removal/change RTNLGRP_IPV6_ROUTE Notifies on IPv6 route arrival/removal/change .Ed .Sh NEXTHOPS All nexthop/nexthop group configuration messages share the common header: .Bd -literal struct nhmsg { unsigned char nh_family; /* transport family */ unsigned char nh_scope; /* ignored on RX, filled by kernel */ unsigned char nh_protocol; /* Routing protocol that installed nh */ unsigned char resvd; unsigned int nh_flags; /* RTNH_F_* flags from route.h */ }; .Ed The .Va nh_family specifies the gateway address family. It can be different from route address family for IPv4 routes with IPv6 nexthops. The .Va nh_protocol is similar to .Va rtm_protocol field, which designates originator application identity. .Pp The following messages are supported: .Ss RTM_NEWNEXTHOP Creates a new nexthop or nexthop group. .Ss RTM_DELNEXTHOP Deletes nexthop or nexthhop group. The required object is specified by the .Dv RTA_NH_ID attribute. .Ss RTM_GETNEXTHOP Fetches a single nexthop or all nexthops/nexthop groups, depending on the .Dv NLM_F_DUMP flag. The following filters are recognised by the kernel: .Pp .Bd -literal -offset indent -compact RTA_NH_ID nexthop or nexthtop group id NHA_GROUPS match only nexthtop groups .Ed .Ss TLVs .Bl -tag -width indent .It Dv RTA_NH_ID (uint32_t) Nexthhop index used to identify particular nexthop or nexthop group. Should be provided by userland at the nexthtop creation time. .It Dv NHA_GROUP This attribute designates the nexthtop group and contains all of its nexthtops and their relative weights. The attribute consists of a list of .Va nexthop_grp structures: .Bd -literal struct nexthop_grp { uint32_t id; /* nexhop userland index */ uint8_t weight; /* weight of this nexthop */ uint8_t resvd1; uint16_t resvd2; }; .Ed .It Dv NHA_GROUP_TYPE (uint16_t) Nexthtop group type, set to one of the following types: .Bd -literal -offset indent -compact NEXTHOP_GRP_TYPE_MPATH default multipath group .Ed .It Dv NHA_BLACKHOLE (flag) Marks the nexthtop as blackhole. .It Dv NHA_OIF (uint32_t) Transmit interface index of the nexthtop. .It Dv NHA_GATEWAY (binary) IPv4/IPv6 gateway address .It Dv NHA_GROUPS (flag) Matches nexthtop groups during dump. .El .Ss Groups The following groups are defined: .Bd -literal -offset indent -compact RTNLGRP_NEXTHOP Notifies on nexthop/groups arrival/removal/change .Ed .Sh INTERFACES All interface configuration messages share the common header: .Bd -literal struct ifinfomsg { unsigned char ifi_family; /* not used, set to 0 */ unsigned char __ifi_pad; unsigned short ifi_type; /* ARPHRD_* */ int ifi_index; /* Interface index */ unsigned ifi_flags; /* IFF_* flags */ unsigned ifi_change; /* IFF_* change mask */ }; .Ed .Ss RTM_NEWLINK Creates a new interface. The only mandatory TLV is .Dv IFLA_IFNAME . The following attributes are returned inside the nested .Dv NLMSGERR_ATTR_COOKIE : .Pp .Bd -literal -offset indent -compact IFLA_NEW_IFINDEX (uint32) created interface index IFLA_IFNAME (string) created interface name .Ed .Ss RTM_DELLINK Deletes the interface specified by .Dv IFLA_IFNAME . .Ss RTM_GETLINK Fetches a single interface or all interfaces in the current VNET, depending on the .Dv NLM_F_DUMP flag. Each interface is reported as a .Dv RTM_NEWLINK message. The following filters are recognised by the kernel: .Pp .Bd -literal -offset indent -compact ifi_index interface index IFLA_IFNAME interface name IFLA_ALT_IFNAME interface name .Ed .Ss TLVs .Bl -tag -width indent .It Dv IFLA_ADDRESS (binary) Llink-level interface address (MAC). .It Dv IFLA_BROADCAST (binary) (readonly) Link-level broadcast address. .It Dv IFLA_IFNAME (string) New interface name. .It Dv IFLA_IFALIAS (string) Interface description. .It Dv IFLA_LINK (uint32_t) (readonly) Interface index. .It Dv IFLA_MASTER (uint32_t) Parent interface index. .It Dv IFLA_LINKINFO (nested) Interface type-specific attributes: .Bd -literal -offset indent -compact IFLA_INFO_KIND (string) interface type ("vlan") IFLA_INFO_DATA (nested) custom attributes .Ed The following types and attributes are supported: .Bl -tag -width indent .It Dv vlan .Bd -literal -offset indent -compact IFLA_VLAN_ID (uint16_t) 802.1Q vlan id IFLA_VLAN_PROTOCOL (uint16_t) Protocol: ETHERTYPE_VLAN or ETHERTYPE_QINQ .Ed .El .It Dv IFLA_OPERSTATE (uint8_t) Interface operational state per RFC 2863. Can be one of the following: .Bd -literal -offset indent -compact IF_OPER_UNKNOWN status can not be determined IF_OPER_NOTPRESENT some (hardware) component not present IF_OPER_DOWN down IF_OPER_LOWERLAYERDOWN some lower-level interface is down IF_OPER_TESTING in some test mode IF_OPER_DORMANT "up" but waiting for some condition (802.1X) IF_OPER_UP ready to pass packets .Ed .It Dv IFLA_STATS64 (readonly) Consists of the following 64-bit counters structure: .Bd -literal struct rtnl_link_stats64 { uint64_t rx_packets; /* total RX packets (IFCOUNTER_IPACKETS) */ uint64_t tx_packets; /* total TX packets (IFCOUNTER_OPACKETS) */ uint64_t rx_bytes; /* total RX bytes (IFCOUNTER_IBYTES) */ uint64_t tx_bytes; /* total TX bytes (IFCOUNTER_OBYTES) */ uint64_t rx_errors; /* RX errors (IFCOUNTER_IERRORS) */ uint64_t tx_errors; /* RX errors (IFCOUNTER_OERRORS) */ uint64_t rx_dropped; /* RX drop (no space in ring/no bufs) (IFCOUNTER_IQDROPS) */ uint64_t tx_dropped; /* TX drop (IFCOUNTER_OQDROPS) */ uint64_t multicast; /* RX multicast packets (IFCOUNTER_IMCASTS) */ uint64_t collisions; /* not supported */ uint64_t rx_length_errors; /* not supported */ uint64_t rx_over_errors; /* not supported */ uint64_t rx_crc_errors; /* not supported */ uint64_t rx_frame_errors; /* not supported */ uint64_t rx_fifo_errors; /* not supported */ uint64_t rx_missed_errors; /* not supported */ uint64_t tx_aborted_errors; /* not supported */ uint64_t tx_carrier_errors; /* not supported */ uint64_t tx_fifo_errors; /* not supported */ uint64_t tx_heartbeat_errors; /* not supported */ uint64_t tx_window_errors; /* not supported */ uint64_t rx_compressed; /* not supported */ uint64_t tx_compressed; /* not supported */ uint64_t rx_nohandler; /* dropped due to no proto handler (IFCOUNTER_NOPROTO) */ }; .Ed .El .Ss Groups The following groups are defined: .Bd -literal -offset indent -compact RTNLGRP_LINK Notifies on interface arrival/removal/change .Ed .Sh INTERFACE ADDRESSES All interface address configuration messages share the common header: .Bd -literal struct ifaddrmsg { uint8_t ifa_family; /* Address family */ uint8_t ifa_prefixlen; /* Prefix length */ uint8_t ifa_flags; /* Address-specific flags */ uint8_t ifa_scope; /* Address scope */ uint32_t ifa_index; /* Link ifindex */ }; .Ed .Pp The .Va ifa_family specifies the address family of the interface address. The .Va ifa_prefixlen specifies the prefix length if applicable for the address family. The .Va ifa_index specifies the interface index of the target interface. .Ss RTM_NEWADDR Not supported .Ss RTM_DELADDR Not supported .Ss RTM_GETADDR Fetches interface addresses in the current VNET matching conditions. Each address is reported as a .Dv RTM_NEWADDR message. The following filters are recognised by the kernel: .Pp .Bd -literal -offset indent -compact ifa_family required family or AF_UNSPEC ifa_index matching interface index or 0 .Ed .Ss TLVs .Bl -tag -width indent .It Dv IFA_ADDRESS (binary) masked interface address or destination address for p2p interfaces. .It Dv IFA_LOCAL (binary) local interface address. Set for IPv4 and p2p addresses. .It Dv IFA_LABEL (string) interface name. .It Dv IFA_BROADCAST (binary) broadcast interface address. .El .Ss Groups The following groups are defined: .Bd -literal -offset indent -compact RTNLGRP_IPV4_IFADDR Notifies on IPv4 ifaddr arrival/removal/change RTNLGRP_IPV6_IFADDR Notifies on IPv6 ifaddr arrival/removal/change .Ed .Sh NEIGHBORS All neighbor configuration messages share the common header: .Bd -literal struct ndmsg { uint8_t ndm_family; uint8_t ndm_pad1; uint16_t ndm_pad2; int32_t ndm_ifindex; uint16_t ndm_state; uint8_t ndm_flags; uint8_t ndm_type; }; .Ed .Pp The .Va ndm_family field specifies the address family (IPv4 or IPv6) of the neighbor. The .Va ndm_ifindex specifies the interface to operate on. The .Va ndm_state represents the entry state according to the neighbor model. The state can be one of the following: .Bd -literal -offset indent -compact NUD_INCOMPLETE No lladdr, address resolution in progress NUD_REACHABLE reachable & recently resolved NUD_STALE has lladdr but it's stale NUD_DELAY has lladdr, is stale, probes delayed NUD_PROBE has lladdr, is stale, probes sent NUD_FAILED unused .Ed .Pp The .Va ndm_flags field stores the options specific to this entry. Available flags: .Bd -literal -offset indent -compact NTF_SELF local station (LLE_IFADDR) NTF_PROXY proxy entry (LLE_PUB) NTF_STICKY permanent entry (LLE_STATIC) NTF_ROUTER dst indicated itself as a router .Ed .Ss RTM_NEWNEIGH Creates new neighbor entry. The mandatory options are .Dv NDA_DST , .Dv NDA_LLADDR and .Dv NDA_IFINDEX . .Ss RTM_DELNEIGH Deletes the neighbor entry. The entry is specified by the combination of .Dv NDA_DST and .Dv NDA_IFINDEX . .Ss RTM_GETNEIGH Fetches a single neighbor or all neighbors in the current VNET, depending on the .Dv NLM_F_DUMP flag. Each entry is reported as .Dv RTM_NEWNEIGH message. The following filters are recognised by the kernel: .Pp .Bd -literal -offset indent -compact ndm_family required family or AF_UNSPEC ndm_ifindex target ifindex NDA_IFINDEX target ifindex .Ed .Ss TLVs .Bl -tag -width indent .It Dv NDA_DST (binary) neighbor IPv4/IPv6 address. .It Dv NDA_LLADDR (binary) neighbor link-level address. .It Dv NDA_IFINDEX (uint32_t) interface index. .It Dv NDA_FLAGS_EXT (uint32_t) extended version of .Va ndm_flags . .El .Ss Groups The following groups are defined: .Bd -literal -offset indent -compact RTNLGRP_NEIGH Notifies on ARP/NDP neighbor arrival/removal/change .Ed .Sh SEE ALSO .Xr netlink 4 , .Xr route 4 .Sh HISTORY The .Dv NETLINK_ROUTE protocol family appeared in .Fx 13.2 . .Sh AUTHORS The netlink was implemented by .An -nosplit .An Alexander Chernikov Aq Mt melifaro@FreeBSD.org . It was derived from the Google Summer of Code 2021 project by .An Ng Peng Nam Sean .