2 .\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
4 .\" %%%LICENSE_START(VERBATIM_ONE_PARA)
5 .\" Permission is granted to distribute possibly modified copies
6 .\" of this page provided the header is included verbatim,
7 .\" and in case of nontrivial modification author and date
8 .\" of the modification is added to the header.
11 .\" Based on the original comments from Alexey Kuznetsov, written with
12 .\" help from Matthew Wilcox.
13 .\" $Id: rtnetlink.7,v 1.8 2000/01/22 01:55:04 freitag Exp $
15 .TH rtnetlink 7 (date) "Linux man-pages (unreleased)"
17 rtnetlink \- Linux routing socket
20 .B #include <asm/types.h>
21 .B #include <linux/netlink.h>
22 .B #include <linux/rtnetlink.h>
23 .B #include <sys/socket.h>
25 .BI "rtnetlink_socket = socket(AF_NETLINK, int " socket_type ", NETLINK_ROUTE);"
28 Rtnetlink allows the kernel's routing tables to be read and altered.
29 It is used within the kernel to communicate between
30 various subsystems, though this usage is not documented here, and for
31 communication with user-space programs.
32 Network routes, IP addresses, link parameters, neighbor setups, queueing
33 disciplines, traffic classes and packet classifiers may all be controlled
37 It is based on netlink messages; see
40 .\" FIXME . ? all these macros could be moved to rtnetlink(3)
41 .SS Routing attributes
42 Some rtnetlink messages have optional attributes after the initial header:
47 unsigned short rta_len; /* Length of option */
48 unsigned short rta_type; /* Type of option */
54 These attributes should be manipulated using only the RTA_* macros
58 Rtnetlink consists of these message types
59 (in addition to standard netlink messages):
61 .BR RTM_NEWLINK ", " RTM_DELLINK ", " RTM_GETLINK
62 Create, remove, or get information about a specific network interface.
63 These messages contain an
65 structure followed by a series of
71 unsigned char ifi_family; /* AF_UNSPEC */
72 unsigned short ifi_type; /* Device type */
73 int ifi_index; /* Interface index */
74 unsigned int ifi_flags; /* Device flags */
75 unsigned int ifi_change; /* change mask */
79 .\" FIXME Document ifinfomsg.ifi_type
81 contains the device flags, see
84 is the unique interface index
85 (since Linux 3.7, it is possible to feed a nonzero value with the
87 message, thus creating a link with the given
90 is reserved for future use and should be always set to 0xFFFFFFFF.
96 rta_type:Value type:Description
98 IFLA_UNSPEC:-:unspecified
99 IFLA_ADDRESS:hardware address:interface L2 address
100 IFLA_BROADCAST:hardware address:L2 broadcast address
101 IFLA_IFNAME:asciiz string:Device name
102 IFLA_MTU:unsigned int:MTU of the device
103 IFLA_LINK:int:Link type
104 IFLA_QDISC:asciiz string:Queueing discipline
107 T}:Interface Statistics
113 .I struct rtnl_link_stats
114 .RI ( "struct net_device_stats"
115 in Linux 2.4 and earlier).
117 .BR RTM_NEWADDR ", " RTM_DELADDR ", " RTM_GETADDR
118 Add, remove, or receive information about an IP address associated with
120 In Linux 2.2, an interface can carry multiple IP addresses,
121 this replaces the alias device concept in Linux 2.0.
122 In Linux 2.2, these messages
123 support IPv4 and IPv6 addresses.
126 structure, optionally followed by
132 unsigned char ifa_family; /* Address type */
133 unsigned char ifa_prefixlen; /* Prefixlength of address */
134 unsigned char ifa_flags; /* Address flags */
135 unsigned char ifa_scope; /* Address scope */
136 unsigned int ifa_index; /* Interface index */
141 is the address family type (currently
146 is the length of the address mask of the address if defined for the
147 family (like for IPv4),
149 is the address scope,
151 is the interface index of the interface the address is associated with.
155 for secondary address (old alias interface),
157 for a permanent address set by the user and other undocumented flags.
163 rta_type:Value type:Description
165 IFA_UNSPEC:-:unspecified
166 IFA_ADDRESS:raw protocol address:interface address
167 IFA_LOCAL:raw protocol address:local address
168 IFA_LABEL:asciiz string:name of the interface
169 IFA_BROADCAST:raw protocol address:broadcast address
170 IFA_ANYCAST:raw protocol address:anycast address
171 IFA_CACHEINFO:struct ifa_cacheinfo:Address information
173 .\" FIXME Document struct ifa_cacheinfo
175 .BR RTM_NEWROUTE ", " RTM_DELROUTE ", " RTM_GETROUTE
176 Create, remove, or receive information about a network route.
177 These messages contain an
179 structure with an optional sequence of
181 structures following.
188 to 0 means you get all entries for the specified routing table.
189 For the other fields, except
197 unsigned char rtm_family; /* Address family of route */
198 unsigned char rtm_dst_len; /* Length of destination */
199 unsigned char rtm_src_len; /* Length of source */
200 unsigned char rtm_tos; /* TOS filter */
201 unsigned char rtm_table; /* Routing table ID;
202 see RTA_TABLE below */
203 unsigned char rtm_protocol; /* Routing protocol; see below */
204 unsigned char rtm_scope; /* See below */
205 unsigned char rtm_type; /* See below */
207 unsigned int rtm_flags;
215 RTN_UNSPEC:unknown route
216 RTN_UNICAST:a gateway or direct route
217 RTN_LOCAL:a local interface route
219 a local broadcast route (sent as a broadcast)
222 a local broadcast route (sent as a unicast)
224 RTN_MULTICAST:a multicast route
225 RTN_BLACKHOLE:a packet dropping route
226 RTN_UNREACHABLE:an unreachable destination
227 RTN_PROHIBIT:a packet rejection route
228 RTN_THROW:continue routing lookup in another table
229 RTN_NAT:a network address translation rule
231 refer to an external resolver (not implemented)
237 rtm_protocol:Route origin
239 RTPROT_UNSPEC:unknown
241 by an ICMP redirect (currently unused)
243 RTPROT_KERNEL:by the kernel
244 RTPROT_BOOT:during boot
245 RTPROT_STATIC:by the administrator
250 are not interpreted by the kernel, they are just for user information.
251 They may be used to tag the source of a routing information or to
252 distinguish between multiple routing daemons.
254 .I <linux/rtnetlink.h>
255 for the routing daemon identifiers which are already assigned.
258 is the distance to the destination:
262 RT_SCOPE_UNIVERSE:global route
264 interior route in the local autonomous system
266 RT_SCOPE_LINK:route on this link
267 RT_SCOPE_HOST:route on the local host
268 RT_SCOPE_NOWHERE:destination doesn't exist
275 are available to the user.
279 have the following meanings:
284 if the route changes, notify the user via rtnetlink
286 RTM_F_CLONED:route is cloned from another route
287 RTM_F_EQUALIZE:a multipath equalizer (not yet implemented)
291 specifies the routing table
295 RT_TABLE_UNSPEC:an unspecified routing table
296 RT_TABLE_DEFAULT:the default table
297 RT_TABLE_MAIN:the main table
298 RT_TABLE_LOCAL:the local table
301 The user may assign arbitrary values between
304 .BR RT_TABLE_DEFAULT .
305 .\" Keep table on same page
312 rta_type:Value type:Description
315 RTA_DST:protocol address:Route destination address
316 RTA_SRC:protocol address:Route source address
317 RTA_IIF:int:Input interface index
318 RTA_OIF:int:Output interface index
319 RTA_GATEWAY:protocol address:The gateway of the route
320 RTA_PRIORITY:int:Priority of route
321 RTA_PREFSRC:protocol address:Preferred source address
322 RTA_METRICS:int:Route metric
324 Multipath nexthop data
328 RTA_PROTOINFO::No longer used
329 RTA_FLOW:int:Route realm
330 RTA_CACHEINFO:struct rta_cacheinfo:(see linux/rtnetlink.h)
331 RTA_SESSION::No longer used
332 RTA_MP_ALGO::No longer used
334 Routing table ID; if set,
339 RTA_MFC_STATS:struct rta_mfc_stats:(see linux/rtnetlink.h)
340 RTA_VIA:struct rtvia:T{
341 Gateway in different AF
344 RTA_NEWDST:protocol address:T{
350 preference (see below)
352 RTA_ENCAP_TYPE:short:T{
353 Encapsulation type for
355 lwtunnels (see below)
357 RTA_ENCAP::Defined by RTA_ENCAP_TYPE
365 contains several packed instances of
367 together with nested RTAs
373 unsigned short rtnh_len; /* Length of struct + length
375 unsigned char rtnh_flags; /* Flags (see
376 linux/rtnetlink.h) */
377 unsigned char rtnh_hops; /* Nexthop priority */
378 int rtnh_ifindex; /* Interface index for this
384 There exist a bunch of
391 useful to handle these structures.
396 unsigned short rtvia_family;
397 unsigned char rtvia_addr[0];
409 .BR ICMPV6_ROUTER_PREF_LOW ,
410 .BR ICMPV6_ROUTER_PREF_MEDIUM ,
412 .B ICMPV6_ROUTER_PREF_HIGH
414 .IR <linux/icmpv6.h> .
418 .BR LWTUNNEL_ENCAP_MPLS ,
419 .BR LWTUNNEL_ENCAP_IP ,
420 .BR LWTUNNEL_ENCAP_ILA ,
422 .B LWTUNNEL_ENCAP_IP6
424 .IR <linux/lwtunnel.h> .
426 .B Fill these values in!
428 .BR RTM_NEWNEIGH ", " RTM_DELNEIGH ", " RTM_GETNEIGH
429 Add, remove, or receive information about a neighbor table
430 entry (e.g., an ARP entry).
431 The message contains an
437 unsigned char ndm_family;
438 int ndm_ifindex; /* Interface index */
439 __u16 ndm_state; /* State */
440 __u8 ndm_flags; /* Flags */
444 struct nda_cacheinfo {
453 is a bit mask of the following states:
457 NUD_INCOMPLETE:a currently resolving cache entry
458 NUD_REACHABLE:a confirmed working cache entry
459 NUD_STALE:an expired cache entry
460 NUD_DELAY:an entry waiting for a timer
461 NUD_PROBE:a cache entry that is currently reprobed
462 NUD_FAILED:an invalid cache entry
463 NUD_NOARP:a device with no destination cache
464 NUD_PERMANENT:a static entry
473 NTF_PROXY:a proxy arp entry
474 NTF_ROUTER:an IPv6 router
478 .\" document the members of the struct better
481 struct has the following meanings for the
487 NDA_UNSPEC:unknown type
488 NDA_DST:a neighbor cache n/w layer destination address
489 NDA_LLADDR:a neighbor cache link layer address
490 NDA_CACHEINFO:cache statistics
498 .I struct nda_cacheinfo
501 .BR RTM_NEWRULE ", " RTM_DELRULE ", " RTM_GETRULE
502 Add, delete, or retrieve a routing rule.
506 .BR RTM_NEWQDISC ", " RTM_DELQDISC ", " RTM_GETQDISC
507 Add, remove, or get a queueing discipline.
508 The message contains a
510 and may be followed by a series of
515 unsigned char tcm_family;
516 int tcm_ifindex; /* interface index */
517 __u32 tcm_handle; /* Qdisc handle */
518 __u32 tcm_parent; /* Parent qdisc */
527 rta_type:Value type:Description
529 TCA_UNSPEC:-:unspecified
530 TCA_KIND:asciiz string:Name of queueing discipline
531 TCA_OPTIONS:byte sequence:Qdisc-specific options follow
532 TCA_STATS:struct tc_stats:Qdisc statistics
533 TCA_XSTATS:qdisc-specific:Module-specific statistics
534 TCA_RATE:struct tc_estimator:Rate limit
537 In addition, various other qdisc-module-specific attributes are allowed.
538 For more information see the appropriate include files.
540 .BR RTM_NEWTCLASS ", " RTM_DELTCLASS ", " RTM_GETTCLASS
541 Add, remove, or get a traffic class.
542 These messages contain a
546 .BR RTM_NEWTFILTER ", " RTM_DELTFILTER ", " RTM_GETTFILTER
547 Add, remove, or receive information about a traffic filter.
548 These messages contain a
553 is a new feature of Linux 2.2.
555 This manual page is incomplete.