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diff --git a/man7/rtnetlink.7 b/man7/rtnetlink.7 new file mode 100644 index 0000000..3b6465f --- /dev/null +++ b/man7/rtnetlink.7 @@ -0,0 +1,558 @@ +'\" t +.\" SPDX-License-Identifier: Linux-man-pages-1-para +.\" +.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>. +.\" +.\" Based on the original comments from Alexey Kuznetsov, written with +.\" help from Matthew Wilcox. +.\" $Id: rtnetlink.7,v 1.8 2000/01/22 01:55:04 freitag Exp $ +.\" +.TH rtnetlink 7 2023-07-15 "Linux man-pages 6.05.01" +.SH NAME +rtnetlink \- Linux routing socket +.SH SYNOPSIS +.nf +.B #include <asm/types.h> +.B #include <linux/netlink.h> +.B #include <linux/rtnetlink.h> +.B #include <sys/socket.h> +.PP +.BI "rtnetlink_socket = socket(AF_NETLINK, int " socket_type ", NETLINK_ROUTE);" +.fi +.SH DESCRIPTION +Rtnetlink allows the kernel's routing tables to be read and altered. +It is used within the kernel to communicate between +various subsystems, though this usage is not documented here, and for +communication with user-space programs. +Network routes, IP addresses, link parameters, neighbor setups, queueing +disciplines, traffic classes and packet classifiers may all be controlled +through +.B NETLINK_ROUTE +sockets. +It is based on netlink messages; see +.BR netlink (7) +for more information. +.\" FIXME . ? all these macros could be moved to rtnetlink(3) +.SS Routing attributes +Some rtnetlink messages have optional attributes after the initial header: +.PP +.in +4n +.EX +struct rtattr { + unsigned short rta_len; /* Length of option */ + unsigned short rta_type; /* Type of option */ + /* Data follows */ +}; +.EE +.in +.PP +These attributes should be manipulated using only the RTA_* macros +or libnetlink, see +.BR rtnetlink (3). +.SS Messages +Rtnetlink consists of these message types +(in addition to standard netlink messages): +.TP +.BR RTM_NEWLINK ", " RTM_DELLINK ", " RTM_GETLINK +Create, remove, or get information about a specific network interface. +These messages contain an +.I ifinfomsg +structure followed by a series of +.I rtattr +structures. +.IP +.EX +struct ifinfomsg { + unsigned char ifi_family; /* AF_UNSPEC */ + unsigned short ifi_type; /* Device type */ + int ifi_index; /* Interface index */ + unsigned int ifi_flags; /* Device flags */ + unsigned int ifi_change; /* change mask */ +}; +.EE +.IP +.\" FIXME Document ifinfomsg.ifi_type +.I ifi_flags +contains the device flags, see +.BR netdevice (7); +.I ifi_index +is the unique interface index +(since Linux 3.7, it is possible to feed a nonzero value with the +.B RTM_NEWLINK +message, thus creating a link with the given +.IR ifindex ); +.I ifi_change +is reserved for future use and should be always set to 0xFFFFFFFF. +.TS +tab(:); +c s s +lb l l. +Routing attributes +rta_type:Value type:Description +_ +IFLA_UNSPEC:-:unspecified +IFLA_ADDRESS:hardware address:interface L2 address +IFLA_BROADCAST:hardware address:L2 broadcast address +IFLA_IFNAME:asciiz string:Device name +IFLA_MTU:unsigned int:MTU of the device +IFLA_LINK:int:Link type +IFLA_QDISC:asciiz string:Queueing discipline +IFLA_STATS:T{ +see below +T}:Interface Statistics +IFLA_PERM_ADDRESS:hardware address:T{ +hardware address provided by device (since Linux 5.5) +T} +.TE +.IP +The value type for +.B IFLA_STATS +is +.I struct rtnl_link_stats +.RI ( "struct net_device_stats" +in Linux 2.4 and earlier). +.TP +.BR RTM_NEWADDR ", " RTM_DELADDR ", " RTM_GETADDR +Add, remove, or receive information about an IP address associated with +an interface. +In Linux 2.2, an interface can carry multiple IP addresses, +this replaces the alias device concept in Linux 2.0. +In Linux 2.2, these messages +support IPv4 and IPv6 addresses. +They contain an +.I ifaddrmsg +structure, optionally followed by +.I rtattr +routing attributes. +.IP +.EX +struct ifaddrmsg { + unsigned char ifa_family; /* Address type */ + unsigned char ifa_prefixlen; /* Prefixlength of address */ + unsigned char ifa_flags; /* Address flags */ + unsigned char ifa_scope; /* Address scope */ + unsigned int ifa_index; /* Interface index */ +}; +.EE +.IP +.I ifa_family +is the address family type (currently +.B AF_INET +or +.BR AF_INET6 ), +.I ifa_prefixlen +is the length of the address mask of the address if defined for the +family (like for IPv4), +.I ifa_scope +is the address scope, +.I ifa_index +is the interface index of the interface the address is associated with. +.I ifa_flags +is a flag word of +.B IFA_F_SECONDARY +for secondary address (old alias interface), +.B IFA_F_PERMANENT +for a permanent address set by the user and other undocumented flags. +.TS +tab(:); +c s s +lb l l. +Attributes +rta_type:Value type:Description +_ +IFA_UNSPEC:-:unspecified +IFA_ADDRESS:raw protocol address:interface address +IFA_LOCAL:raw protocol address:local address +IFA_LABEL:asciiz string:name of the interface +IFA_BROADCAST:raw protocol address:broadcast address +IFA_ANYCAST:raw protocol address:anycast address +IFA_CACHEINFO:struct ifa_cacheinfo:Address information +.TE +.\" FIXME Document struct ifa_cacheinfo +.TP +.BR RTM_NEWROUTE ", " RTM_DELROUTE ", " RTM_GETROUTE +Create, remove, or receive information about a network route. +These messages contain an +.I rtmsg +structure with an optional sequence of +.I rtattr +structures following. +For +.BR RTM_GETROUTE , +setting +.I rtm_dst_len +and +.I rtm_src_len +to 0 means you get all entries for the specified routing table. +For the other fields, except +.I rtm_table +and +.IR rtm_protocol , +0 is the wildcard. +.IP +.EX +struct rtmsg { + unsigned char rtm_family; /* Address family of route */ + unsigned char rtm_dst_len; /* Length of destination */ + unsigned char rtm_src_len; /* Length of source */ + unsigned char rtm_tos; /* TOS filter */ + unsigned char rtm_table; /* Routing table ID; + see RTA_TABLE below */ + unsigned char rtm_protocol; /* Routing protocol; see below */ + unsigned char rtm_scope; /* See below */ + unsigned char rtm_type; /* See below */ +\& + unsigned int rtm_flags; +}; +.EE +.TS +tab(:); +lb l. +rtm_type:Route type +_ +RTN_UNSPEC:unknown route +RTN_UNICAST:a gateway or direct route +RTN_LOCAL:a local interface route +RTN_BROADCAST:T{ +a local broadcast route (sent as a broadcast) +T} +RTN_ANYCAST:T{ +a local broadcast route (sent as a unicast) +T} +RTN_MULTICAST:a multicast route +RTN_BLACKHOLE:a packet dropping route +RTN_UNREACHABLE:an unreachable destination +RTN_PROHIBIT:a packet rejection route +RTN_THROW:continue routing lookup in another table +RTN_NAT:a network address translation rule +RTN_XRESOLVE:T{ +refer to an external resolver (not implemented) +T} +.TE +.TS +tab(:); +lb l. +rtm_protocol:Route origin +_ +RTPROT_UNSPEC:unknown +RTPROT_REDIRECT:T{ +by an ICMP redirect (currently unused) +T} +RTPROT_KERNEL:by the kernel +RTPROT_BOOT:during boot +RTPROT_STATIC:by the administrator +.TE +.sp 1 +Values larger than +.B RTPROT_STATIC +are not interpreted by the kernel, they are just for user information. +They may be used to tag the source of a routing information or to +distinguish between multiple routing daemons. +See +.I <linux/rtnetlink.h> +for the routing daemon identifiers which are already assigned. +.IP +.I rtm_scope +is the distance to the destination: +.TS +tab(:); +lb l. +RT_SCOPE_UNIVERSE:global route +RT_SCOPE_SITE:T{ +interior route in the local autonomous system +T} +RT_SCOPE_LINK:route on this link +RT_SCOPE_HOST:route on the local host +RT_SCOPE_NOWHERE:destination doesn't exist +.TE +.sp 1 +The values between +.B RT_SCOPE_UNIVERSE +and +.B RT_SCOPE_SITE +are available to the user. +.IP +The +.I rtm_flags +have the following meanings: +.TS +tab(:); +lb l. +RTM_F_NOTIFY:T{ +if the route changes, notify the user via rtnetlink +T} +RTM_F_CLONED:route is cloned from another route +RTM_F_EQUALIZE:a multipath equalizer (not yet implemented) +.TE +.sp 1 +.I rtm_table +specifies the routing table +.TS +tab(:); +lb l. +RT_TABLE_UNSPEC:an unspecified routing table +RT_TABLE_DEFAULT:the default table +RT_TABLE_MAIN:the main table +RT_TABLE_LOCAL:the local table +.TE +.sp 1 +The user may assign arbitrary values between +.B RT_TABLE_UNSPEC +and +.BR RT_TABLE_DEFAULT . +.\" Keep table on same page +.bp +1 +.TS +tab(:); +c s s +lb2 l2 l. +Attributes +rta_type:Value type:Description +_ +RTA_UNSPEC:-:ignored +RTA_DST:protocol address:Route destination address +RTA_SRC:protocol address:Route source address +RTA_IIF:int:Input interface index +RTA_OIF:int:Output interface index +RTA_GATEWAY:protocol address:The gateway of the route +RTA_PRIORITY:int:Priority of route +RTA_PREFSRC:protocol address:Preferred source address +RTA_METRICS:int:Route metric +RTA_MULTIPATH::T{ +Multipath nexthop data +br +(see below). +T} +RTA_PROTOINFO::No longer used +RTA_FLOW:int:Route realm +RTA_CACHEINFO:struct rta_cacheinfo:(see linux/rtnetlink.h) +RTA_SESSION::No longer used +RTA_MP_ALGO::No longer used +RTA_TABLE:int:T{ +Routing table ID; if set, +.br +rtm_table is ignored +T} +RTA_MARK:int: +RTA_MFC_STATS:struct rta_mfc_stats:(see linux/rtnetlink.h) +RTA_VIA:struct rtvia:T{ +Gateway in different AF +(see below) +T} +RTA_NEWDST:protocol address:T{ +Change packet +destination address +T} +RTA_PREF:char:T{ +RFC4191 IPv6 router +preference (see below) +T} +RTA_ENCAP_TYPE:short:T{ +Encapsulation type for +.br +lwtunnels (see below) +T} +RTA_ENCAP::Defined by RTA_ENCAP_TYPE +RTA_EXPIRES:int:T{ +Expire time for IPv6 +routes (in seconds) +T} +.TE +.IP +.B RTA_MULTIPATH +contains several packed instances of +.I struct rtnexthop +together with nested RTAs +.RB ( RTA_GATEWAY ): +.IP +.in +4n +.EX +struct rtnexthop { + unsigned short rtnh_len; /* Length of struct + length + of RTAs */ + unsigned char rtnh_flags; /* Flags (see + linux/rtnetlink.h) */ + unsigned char rtnh_hops; /* Nexthop priority */ + int rtnh_ifindex; /* Interface index for this + nexthop */ +} +.EE +.in +.IP +There exist a bunch of +.B RTNH_* +macros similar to +.B RTA_* +and +.B NLHDR_* +macros +useful to handle these structures. +.IP +.in +4n +.EX +struct rtvia { + unsigned short rtvia_family; + unsigned char rtvia_addr[0]; +}; +.EE +.in +.IP +.I rtvia_addr +is the address, +.I rtvia_family +is its family type. +.IP +.B RTA_PREF +may contain values +.BR ICMPV6_ROUTER_PREF_LOW , +.BR ICMPV6_ROUTER_PREF_MEDIUM , +and +.B ICMPV6_ROUTER_PREF_HIGH +defined incw +.IR <linux/icmpv6.h> . +.IP +.B RTA_ENCAP_TYPE +may contain values +.BR LWTUNNEL_ENCAP_MPLS , +.BR LWTUNNEL_ENCAP_IP , +.BR LWTUNNEL_ENCAP_ILA , +or +.B LWTUNNEL_ENCAP_IP6 +defined in +.IR <linux/lwtunnel.h> . +.IP +.B Fill these values in! +.TP +.BR RTM_NEWNEIGH ", " RTM_DELNEIGH ", " RTM_GETNEIGH +Add, remove, or receive information about a neighbor table +entry (e.g., an ARP entry). +The message contains an +.I ndmsg +structure. +.IP +.EX +struct ndmsg { + unsigned char ndm_family; + int ndm_ifindex; /* Interface index */ + __u16 ndm_state; /* State */ + __u8 ndm_flags; /* Flags */ + __u8 ndm_type; +}; +\& +struct nda_cacheinfo { + __u32 ndm_confirmed; + __u32 ndm_used; + __u32 ndm_updated; + __u32 ndm_refcnt; +}; +.EE +.IP +.I ndm_state +is a bit mask of the following states: +.TS +tab(:); +lb l. +NUD_INCOMPLETE:a currently resolving cache entry +NUD_REACHABLE:a confirmed working cache entry +NUD_STALE:an expired cache entry +NUD_DELAY:an entry waiting for a timer +NUD_PROBE:a cache entry that is currently reprobed +NUD_FAILED:an invalid cache entry +NUD_NOARP:a device with no destination cache +NUD_PERMANENT:a static entry +.TE +.sp 1 +Valid +.I ndm_flags +are: +.TS +tab(:); +lb l. +NTF_PROXY:a proxy arp entry +NTF_ROUTER:an IPv6 router +.TE +.sp 1 +.\" FIXME . +.\" document the members of the struct better +The +.I rtattr +struct has the following meanings for the +.I rta_type +field: +.TS +tab(:); +lb l. +NDA_UNSPEC:unknown type +NDA_DST:a neighbor cache n/w layer destination address +NDA_LLADDR:a neighbor cache link layer address +NDA_CACHEINFO:cache statistics +.TE +.sp 1 +If the +.I rta_type +field is +.BR NDA_CACHEINFO , +then a +.I struct nda_cacheinfo +header follows. +.TP +.BR RTM_NEWRULE ", " RTM_DELRULE ", " RTM_GETRULE +Add, delete, or retrieve a routing rule. +Carries a +.I struct rtmsg +.TP +.BR RTM_NEWQDISC ", " RTM_DELQDISC ", " RTM_GETQDISC +Add, remove, or get a queueing discipline. +The message contains a +.I struct tcmsg +and may be followed by a series of +attributes. +.IP +.EX +struct tcmsg { + unsigned char tcm_family; + int tcm_ifindex; /* interface index */ + __u32 tcm_handle; /* Qdisc handle */ + __u32 tcm_parent; /* Parent qdisc */ + __u32 tcm_info; +}; +.EE +.TS +tab(:); +c s s +lb2 l2 l. +Attributes +rta_type:Value type:Description +_ +TCA_UNSPEC:-:unspecified +TCA_KIND:asciiz string:Name of queueing discipline +TCA_OPTIONS:byte sequence:Qdisc-specific options follow +TCA_STATS:struct tc_stats:Qdisc statistics +TCA_XSTATS:qdisc-specific:Module-specific statistics +TCA_RATE:struct tc_estimator:Rate limit +.TE +.sp 1 +In addition, various other qdisc-module-specific attributes are allowed. +For more information see the appropriate include files. +.TP +.BR RTM_NEWTCLASS ", " RTM_DELTCLASS ", " RTM_GETTCLASS +Add, remove, or get a traffic class. +These messages contain a +.I struct tcmsg +as described above. +.TP +.BR RTM_NEWTFILTER ", " RTM_DELTFILTER ", " RTM_GETTFILTER +Add, remove, or receive information about a traffic filter. +These messages contain a +.I struct tcmsg +as described above. +.SH VERSIONS +.B rtnetlink +is a new feature of Linux 2.2. +.SH BUGS +This manual page is incomplete. +.SH SEE ALSO +.BR cmsg (3), +.BR rtnetlink (3), +.BR ip (7), +.BR netlink (7) |