# SPDX-License-Identifier: GPL-2.0-only # # Network configuration # menuconfig NET bool "Networking support" select NLATTR select GENERIC_NET_UTILS select BPF help Unless you really know what you are doing, you should say Y here. The reason is that some programs need kernel networking support even when running on a stand-alone machine that isn't connected to any other computer. If you are upgrading from an older kernel, you should consider updating your networking tools too because changes in the kernel and the tools often go hand in hand. The tools are contained in the package net-tools, the location and version number of which are given in . For a general introduction to Linux networking, it is highly recommended to read the NET-HOWTO, available from . if NET config WANT_COMPAT_NETLINK_MESSAGES bool help This option can be selected by other options that need compat netlink messages. config COMPAT_NETLINK_MESSAGES def_bool y depends on COMPAT depends on WEXT_CORE || WANT_COMPAT_NETLINK_MESSAGES help This option makes it possible to send different netlink messages to tasks depending on whether the task is a compat task or not. To achieve this, you need to set skb_shinfo(skb)->frag_list to the compat skb before sending the skb, the netlink code will sort out which message to actually pass to the task. Newly written code should NEVER need this option but do compat-independent messages instead! config NET_INGRESS bool config NET_EGRESS bool config NET_XGRESS select NET_INGRESS select NET_EGRESS bool config NET_REDIRECT bool config SKB_DECRYPTED bool config SKB_EXTENSIONS bool config NET_DEVMEM def_bool y depends on DMA_SHARED_BUFFER depends on GENERIC_ALLOCATOR menu "Networking options" source "net/packet/Kconfig" source "net/unix/Kconfig" source "net/tls/Kconfig" source "net/xfrm/Kconfig" source "net/iucv/Kconfig" source "net/smc/Kconfig" source "net/xdp/Kconfig" config NET_HANDSHAKE bool depends on SUNRPC || NVME_TARGET_TCP || NVME_TCP default y config NET_HANDSHAKE_KUNIT_TEST tristate "KUnit tests for the handshake upcall mechanism" if !KUNIT_ALL_TESTS default KUNIT_ALL_TESTS depends on KUNIT help This builds the KUnit tests for the handshake upcall mechanism. KUnit tests run during boot and output the results to the debug log in TAP format (https://testanything.org/). Only useful for kernel devs running KUnit test harness and are not for inclusion into a production build. For more information on KUnit and unit tests in general, refer to the KUnit documentation in Documentation/dev-tools/kunit/. config INET bool "TCP/IP networking" help These are the protocols used on the Internet and on most local Ethernets. It is highly recommended to say Y here (this will enlarge your kernel by about 400 KB), since some programs (e.g. the X window system) use TCP/IP even if your machine is not connected to any other computer. You will get the so-called loopback device which allows you to ping yourself (great fun, that!). For an excellent introduction to Linux networking, please read the Linux Networking HOWTO, available from . If you say Y here and also to "/proc file system support" and "Sysctl support" below, you can change various aspects of the behavior of the TCP/IP code by writing to the (virtual) files in /proc/sys/net/ipv4/*; the options are explained in the file . Short answer: say Y. if INET source "net/ipv4/Kconfig" source "net/ipv6/Kconfig" source "net/netlabel/Kconfig" source "net/mptcp/Kconfig" endif # if INET config NETWORK_SECMARK bool "Security Marking" help This enables security marking of network packets, similar to nfmark, but designated for security purposes. If you are unsure how to answer this question, answer N. config NET_PTP_CLASSIFY def_bool n config NETWORK_PHY_TIMESTAMPING bool "Timestamping in PHY devices" select NET_PTP_CLASSIFY help This allows timestamping of network packets by PHYs (or other MII bus snooping devices) with hardware timestamping capabilities. This option adds some overhead in the transmit and receive paths. If you are unsure how to answer this question, answer N. menuconfig NETFILTER bool "Network packet filtering framework (Netfilter)" help Netfilter is a framework for filtering and mangling network packets that pass through your Linux box. The most common use of packet filtering is to run your Linux box as a firewall protecting a local network from the Internet. The type of firewall provided by this kernel support is called a "packet filter", which means that it can reject individual network packets based on type, source, destination etc. The other kind of firewall, a "proxy-based" one, is more secure but more intrusive and more bothersome to set up; it inspects the network traffic much more closely, modifies it and has knowledge about the higher level protocols, which a packet filter lacks. Moreover, proxy-based firewalls often require changes to the programs running on the local clients. Proxy-based firewalls don't need support by the kernel, but they are often combined with a packet filter, which only works if you say Y here. You should also say Y here if you intend to use your Linux box as the gateway to the Internet for a local network of machines without globally valid IP addresses. This is called "masquerading": if one of the computers on your local network wants to send something to the outside, your box can "masquerade" as that computer, i.e. it forwards the traffic to the intended outside destination, but modifies the packets to make it look like they came from the firewall box itself. It works both ways: if the outside host replies, the Linux box will silently forward the traffic to the correct local computer. This way, the computers on your local net are completely invisible to the outside world, even though they can reach the outside and can receive replies. It is even possible to run globally visible servers from within a masqueraded local network using a mechanism called portforwarding. Masquerading is also often called NAT (Network Address Translation). Another use of Netfilter is in transparent proxying: if a machine on the local network tries to connect to an outside host, your Linux box can transparently forward the traffic to a local server, typically a caching proxy server. Yet another use of Netfilter is building a bridging firewall. Using a bridge with Network packet filtering enabled makes iptables "see" the bridged traffic. For filtering on the lower network and Ethernet protocols over the bridge, use ebtables (under bridge netfilter configuration). Various modules exist for netfilter which replace the previous masquerading (ipmasqadm), packet filtering (ipchains), transparent proxying, and portforwarding mechanisms. Please see under "iptables" for the location of these packages. if NETFILTER config NETFILTER_ADVANCED bool "Advanced netfilter configuration" depends on NETFILTER default y help If you say Y here you can select between all the netfilter modules. If you say N the more unusual ones will not be shown and the basic ones needed by most people will default to 'M'. If unsure, say Y. config BRIDGE_NETFILTER tristate "Bridged IP/ARP packets filtering" depends on BRIDGE depends on NETFILTER && INET depends on NETFILTER_ADVANCED select NETFILTER_FAMILY_BRIDGE select SKB_EXTENSIONS help Enabling this option will let arptables resp. iptables see bridged ARP resp. IP traffic. If you want a bridging firewall, you probably want this option enabled. Enabling or disabling this option doesn't enable or disable ebtables. If unsure, say N. source "net/netfilter/Kconfig" source "net/ipv4/netfilter/Kconfig" source "net/ipv6/netfilter/Kconfig" source "net/bridge/netfilter/Kconfig" endif source "net/dccp/Kconfig" source "net/sctp/Kconfig" source "net/rds/Kconfig" source "net/tipc/Kconfig" source "net/atm/Kconfig" source "net/l2tp/Kconfig" source "net/802/Kconfig" source "net/bridge/Kconfig" source "net/dsa/Kconfig" source "net/8021q/Kconfig" source "net/llc/Kconfig" source "net/appletalk/Kconfig" source "net/x25/Kconfig" source "net/lapb/Kconfig" source "net/phonet/Kconfig" source "net/6lowpan/Kconfig" source "net/ieee802154/Kconfig" source "net/mac802154/Kconfig" source "net/sched/Kconfig" source "net/dcb/Kconfig" source "net/dns_resolver/Kconfig" source "net/batman-adv/Kconfig" source "net/openvswitch/Kconfig" source "net/vmw_vsock/Kconfig" source "net/netlink/Kconfig" source "net/mpls/Kconfig" source "net/nsh/Kconfig" source "net/hsr/Kconfig" source "net/switchdev/Kconfig" source "net/l3mdev/Kconfig" source "net/qrtr/Kconfig" source "net/ncsi/Kconfig" config PCPU_DEV_REFCNT bool "Use percpu variables to maintain network device refcount" depends on SMP default y help network device refcount are using per cpu variables if this option is set. This can be forced to N to detect underflows (with a performance drop). config MAX_SKB_FRAGS int "Maximum number of fragments per skb_shared_info" range 17 45 default 17 help Having more fragments per skb_shared_info can help GRO efficiency. This helps BIG TCP workloads, but might expose bugs in some legacy drivers. This also increases memory overhead of small packets, and in drivers using build_skb(). If unsure, say 17. config RPS bool "Receive packet steering" depends on SMP && SYSFS default y help Software receive side packet steering (RPS) distributes the load of received packet processing across multiple CPUs. config RFS_ACCEL bool "Hardware acceleration of RFS" depends on RPS select CPU_RMAP default y help Allowing drivers for multiqueue hardware with flow filter tables to accelerate RFS. config SOCK_RX_QUEUE_MAPPING bool config XPS bool depends on SMP select SOCK_RX_QUEUE_MAPPING default y config HWBM bool config CGROUP_NET_PRIO bool "Network priority cgroup" depends on CGROUPS select SOCK_CGROUP_DATA help Cgroup subsystem for use in assigning processes to network priorities on a per-interface basis. config CGROUP_NET_CLASSID bool "Network classid cgroup" depends on CGROUPS select SOCK_CGROUP_DATA help Cgroup subsystem for use as general purpose socket classid marker that is being used in cls_cgroup and for netfilter matching. config NET_RX_BUSY_POLL bool default y if !PREEMPT_RT || (PREEMPT_RT && !NETCONSOLE) config BQL bool prompt "Enable Byte Queue Limits" depends on SYSFS select DQL default y config BPF_STREAM_PARSER bool "enable BPF STREAM_PARSER" depends on INET depends on BPF_SYSCALL depends on CGROUP_BPF select STREAM_PARSER select NET_SOCK_MSG help Enabling this allows a TCP stream parser to be used with BPF_MAP_TYPE_SOCKMAP. config NET_FLOW_LIMIT bool "Net flow limit" depends on RPS default y help The network stack has to drop packets when a receive processing CPU's backlog reaches netdev_max_backlog. If a few out of many active flows generate the vast majority of load, drop their traffic earlier to maintain capacity for the other flows. This feature provides servers with many clients some protection against DoS by a single (spoofed) flow that greatly exceeds average workload. menu "Network testing" config NET_PKTGEN tristate "Packet Generator (USE WITH CAUTION)" depends on INET && PROC_FS help This module will inject preconfigured packets, at a configurable rate, out of a given interface. It is used for network interface stress testing and performance analysis. If you don't understand what was just said, you don't need it: say N. Documentation on how to use the packet generator can be found at . To compile this code as a module, choose M here: the module will be called pktgen. config NET_DROP_MONITOR tristate "Network packet drop alerting service" depends on INET && TRACEPOINTS help This feature provides an alerting service to userspace in the event that packets are discarded in the network stack. Alerts are broadcast via netlink socket to any listening user space process. If you don't need network drop alerts, or if you are ok just checking the various proc files and other utilities for drop statistics, say N here. endmenu endmenu source "net/ax25/Kconfig" source "net/can/Kconfig" source "net/bluetooth/Kconfig" source "net/rxrpc/Kconfig" source "net/kcm/Kconfig" source "net/strparser/Kconfig" source "net/mctp/Kconfig" config FIB_RULES bool menuconfig WIRELESS bool "Wireless" depends on !S390 default y if WIRELESS source "net/wireless/Kconfig" source "net/mac80211/Kconfig" endif # WIRELESS source "net/rfkill/Kconfig" source "net/9p/Kconfig" source "net/caif/Kconfig" source "net/ceph/Kconfig" source "net/nfc/Kconfig" source "net/psample/Kconfig" source "net/ife/Kconfig" config LWTUNNEL bool "Network light weight tunnels" help This feature provides an infrastructure to support light weight tunnels like mpls. There is no netdevice associated with a light weight tunnel endpoint. Tunnel encapsulation parameters are stored with light weight tunnel state associated with fib routes. config LWTUNNEL_BPF bool "Execute BPF program as route nexthop action" depends on LWTUNNEL && INET default y if LWTUNNEL=y help Allows to run BPF programs as a nexthop action following a route lookup for incoming and outgoing packets. config DST_CACHE bool default n config GRO_CELLS bool default n config SOCK_VALIDATE_XMIT bool config NET_IEEE8021Q_HELPERS bool config NET_SELFTESTS def_tristate PHYLIB depends on PHYLIB && INET config NET_SOCK_MSG bool default n help The NET_SOCK_MSG provides a framework for plain sockets (e.g. TCP) or ULPs (upper layer modules, e.g. TLS) to process L7 application data with the help of BPF programs. config NET_DEVLINK bool default n config PAGE_POOL bool config PAGE_POOL_STATS default n bool "Page pool stats" depends on PAGE_POOL help Enable page pool statistics to track page allocation and recycling in page pools. This option incurs additional CPU cost in allocation and recycle paths and additional memory cost to store the statistics. These statistics are only available if this option is enabled and if the driver using the page pool supports exporting this data. If unsure, say N. config FAILOVER tristate "Generic failover module" help The failover module provides a generic interface for paravirtual drivers to register a netdev and a set of ops with a failover instance. The ops are used as event handlers that get called to handle netdev register/unregister/link change/name change events on slave pci ethernet devices with the same mac address as the failover netdev. This enables paravirtual drivers to use a VF as an accelerated low latency datapath. It also allows live migration of VMs with direct attached VFs by failing over to the paravirtual datapath when the VF is unplugged. config ETHTOOL_NETLINK bool "Netlink interface for ethtool" select DIMLIB default y help An alternative userspace interface for ethtool based on generic netlink. It provides better extensibility and some new features, e.g. notification messages. config NETDEV_ADDR_LIST_TEST tristate "Unit tests for device address list" default KUNIT_ALL_TESTS depends on KUNIT config NET_TEST tristate "KUnit tests for networking" if !KUNIT_ALL_TESTS depends on KUNIT default KUNIT_ALL_TESTS help KUnit tests covering core networking infra, such as sk_buff. If unsure, say N. endif # if NET