'\" t
-.\" Don't remove the line above, it tells man that tbl is needed.
.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" %%%LICENSE_START(VERBATIM_ONE_PARA)
.\" Permission is granted to distribute possibly modified copies
.\" of this page provided the header is included verbatim,
.\" and in case of nontrivial modification author and date
.\" of the modification is added to the header.
+.\" %%%LICENSE_END
+.\"
.\" 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 1999-04-30 "Linux" "Linux Programmer's Manual"
+.\"
+.TH RTNETLINK 7 2020-02-09 "Linux" "Linux Programmer's Manual"
.SH NAME
-rtnetlink, NETLINK_ROUTE \- Linux IPv4 routing socket
+rtnetlink \- Linux IPv4 routing socket
.SH SYNOPSIS
.B #include <asm/types.h>
.br
.B #include <linux/rtnetlink.h>
.br
.B #include <sys/socket.h>
-
-.BI "rtnetlink_socket = socket(PF_NETLINK, int " socket_type ", NETLINK_ROUTE);"
+.PP
+.BI "rtnetlink_socket = socket(AF_NETLINK, int " socket_type ", NETLINK_ROUTE);"
.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, neighbour setups, queueing
+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
+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"
+.\" FIXME . ? all these macros could be moved to rtnetlink(3)
+.SS Routing attributes
Some rtnetlink messages have optional attributes after the initial header:
-
-.nf
+.PP
+.in +4n
+.EX
struct rtattr {
unsigned short rta_len; /* Length of option */
unsigned short rta_type; /* Type of option */
/* Data follows */
};
-.fi
-
-These attributes should be only manipulated using the RTA_* macros
+.EE
+.in
+.PP
+These attributes should be manipulated using only the RTA_* macros
or libnetlink, see
.BR rtnetlink (3).
.SS Messages
.BR RTM_NEWLINK ", " RTM_DELLINK ", " RTM_GETLINK
Create, remove or get information about a specific network interface.
These messages contain an
-.B ifinfomsg
+.I ifinfomsg
structure followed by a series of
-.B rtattr
+.I rtattr
structures.
-
-.nf
+.IP
+.EX
struct ifinfomsg {
unsigned char ifi_family; /* AF_UNSPEC */
unsigned short ifi_type; /* Device type */
unsigned int ifi_flags; /* Device flags */
unsigned int ifi_change; /* change mask */
};
-.fi
-
-.\" FIXME ifi_type
-.B ifi_flags
+.EE
+.IP
+.\" FIXME Document ifinfomsg.ifi_type
+.I ifi_flags
contains the device flags, see
.BR netdevice (7);
-.B ifi_index
-is the unique interface index,
-.B ifi_change
+.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
+c s s
l l l.
Routing attributes
-rta_type:value type:description
+rta_type:Value type:Description
_
-IFLA_UNSPEC:-:unspecified.
+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_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.
+T}:Interface Statistics
.TE
-.sp
-The value type for IFLA_STATS is \fIstruct net_device_stats\fP.
+.PP
+The value type for
+.B IFLA_STATS
+is
+.IR "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,
+In Linux 2.2, an interface can carry multiple IP addresses,
this replaces the alias device concept in 2.0.
-In Linux 2.2 these messages
+In Linux 2.2, these messages
support IPv4 and IPv6 addresses.
They contain an
-.B ifaddrmsg
+.I ifaddrmsg
structure, optionally followed by
-.B rtaddr
+.I rtattr
routing attributes.
-
-.nf
+.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 */
- int ifa_index; /* Interface index */
+ unsigned int ifa_index; /* Interface index */
};
-.fi
-
-.B ifa_family
+.EE
+.IP
+.I ifa_family
is the address family type (currently
.B AF_INET
or
.BR AF_INET6 ),
-.B ifa_prefixlen
+.I ifa_prefixlen
is the length of the address mask of the address if defined for the
family (like for IPv4),
-.B ifa_scope
+.I ifa_scope
is the address scope,
-.B ifa_index
+.I ifa_index
is the interface index of the interface the address is associated with.
-.B ifa_flags
+.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
+c s s
l l l.
Attributes
-rta_type:value type:description
+rta_type:Value type:Description
_
-IFA_UNSPEC:-:unspecified.
+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_BROADCAST:raw protocol address:broadcast address
IFA_ANYCAST:raw protocol address:anycast address
-IFA_CACHEINFO:struct ifa_cacheinfo:Address information.
+IFA_CACHEINFO:struct ifa_cacheinfo:Address information
.TE
-.\" FIXME struct ifa_cacheinfo
+.\" 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
-.B rtmsg
+.I rtmsg
structure with an optional sequence of
-.B rtattr
+.I rtattr
structures following.
For
-.B RTM_GETROUTE
+.BR RTM_GETROUTE ,
setting
-.B rtm_dst_len
+.I rtm_dst_len
and
-.B rtm_src_len
+.I rtm_src_len
to 0 means you get all entries for the specified routing table.
-For the other fields except
-.B rtm_table
+For the other fields, except
+.I rtm_table
and
-.B rtm_protocol
+.IR rtm_protocol ,
0 is the wildcard.
-
-.nf
+.IP
+.EX
struct rtmsg {
unsigned char rtm_family; /* Address family of route */
- unsigned char rtm_dst_len; /* Length of source */
- unsigned char rtm_src_len; /* Length of destination */
+ 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 */
+ 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;
};
-.fi
-
+.EE
.TS
tab(:);
-l l
l l.
rtm_type:Route type
_
refer to an external resolver (not implemented)
T}
.TE
-
.TS
tab(:);
l l.
-rtm_protocol:Route origin.
+rtm_protocol:Route origin
_
RTPROT_UNSPEC:unknown
RTPROT_REDIRECT:T{
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
-.IR <linux/rtnetlink.h>
+.I <linux/rtnetlink.h>
for the routing daemon identifiers which are already assigned.
-
-.B rtm_scope
+.IP
+.I rtm_scope
is the distance to the destination:
-
.TS
tab(:);
l l.
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
-.B rtm_flags
+.I rtm_flags
have the following meanings:
-
.TS
tab(:);
l l.
if the route changes, notify the user via rtnetlink
T}
RTM_F_CLONED:route is cloned from another route
-RTM_F_EQUALIZE:a multicast equalizer (not yet implemented)
+RTM_F_EQUALIZE:a multipath equalizer (not yet implemented)
.TE
-
-.B rtm_table
+.sp 1
+.I rtm_table
specifies the routing table
-
.TS
tab(:);
l l.
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
-l l l.
+c s s
+l2 l2 l.
Attributes
-rta_type:value type:description
+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_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::
+RTA_PRIORITY:int:Priority of route
+RTA_PREFSRC:protocol address:Preferred source address
RTA_METRICS:int:Route metric
-RTA_MULTIPATH::
-RTA_PROTOINFO::
-RTA_FLOW::
-RTA_CACHEINFO::
+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
-
+.PP
+.I RTA_MULTIPATH
+contains several packed instances of
+.I struct rtnexthop
+together with nested RTAs
+.RB ( RTA_GATEWAY ):
+.PP
+.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
+.PP
+There exist a bunch of RTNH_* macros similar to RTA_* and NLHDR_* macros
+useful to handle these structures.
+.PP
+.nf
+.in +4n
+.EX
+struct rtvia {
+ unsigned short rtvia_family;
+ unsigned char rtvia_addr[0];
+};
+.EE
+.in
+.PP
+.I rtvia_addr
+is the address,
+.I rtvia_family
+is its family type.
+.PP
+.I RTA_PREF
+may contain values ICMPV6_ROUTER_PREF_LOW,
+ICMPV6_ROUTER_PREF_MEDIUM and
+ICMPV6_ROUTER_PREF_HIGH defined in <linux/icmpv6.h>
+.PP
+.I RTA_ENCAP_TYPE
+may contain values
+LWTUNNEL_ENCAP_MPLS, LWTUNNEL_ENCAP_IP,
+LWTUNNEL_ENCAP_ILA or LWTUNNEL_ENCAP_IP6
+defined in <linux/lwtunnel.h>.
+.sp 1
.B Fill these values in!
.TP
.BR RTM_NEWNEIGH ", " RTM_DELNEIGH ", " RTM_GETNEIGH
-Add, remove or receive information about a neighbour table
-entry (e.g. an ARP entry).
+Add, remove or receive information about a neighbor table
+entry (e.g., an ARP entry).
The message contains an
-.B ndmsg
+.I ndmsg
structure.
-
-.nf
+.IP
+.EX
struct ndmsg {
unsigned char ndm_family;
int ndm_ifindex; /* Interface index */
__u32 ndm_updated;
__u32 ndm_refcnt;
};
-.fi
-
-.B ndm_state
-is a bitmask of the following states:
-
+.EE
+.IP
+.I ndm_state
+is a bit mask of the following states:
.TS
tab(:);
l l.
NUD_NOARP:a device with no destination cache
NUD_PERMANENT:a static entry
.TE
-
+.sp 1
Valid
-.B ndm_flags
+.I ndm_flags
are:
-
.TS
tab(:);
l l.
NTF_PROXY:a proxy arp entry
NTF_ROUTER:an IPv6 router
.TE
-
-.B document the members of the struct better
-
+.sp 1
+.\" FIXME .
+.\" document the members of the struct better
The
-.B rtaddr
+.I rtattr
struct has the following meanings for the
-.B rta_type
+.I rta_type
field:
-
.TS
tab(:);
l l.
NDA_UNSPEC:unknown type
-NDA_DST:a neighbour cache n/w layer destination address
-NDA_LLADDR:a neighbour cache link layer address
-NDA_CACHEINFO:cache statistics.
+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
-.B rta_type
+.I rta_type
field is
-.B NDA_CACHEINFO
+.BR NDA_CACHEINFO ,
then a
.I struct nda_cacheinfo
header follows
.I struct tcmsg
and may be followed by a series of
attributes.
-
-.nf
+.IP
+.EX
struct tcmsg {
unsigned char tcm_family;
int tcm_ifindex; /* interface index */
__u32 tcm_parent; /* Parent qdisc */
__u32 tcm_info;
};
-.fi
-
+.EE
.TS
tab(:);
-c
-l l l.
+c s s
+l2 l2 l.
Attributes
-rta_type:value type:Description
+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.
+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
-
-In addition various other qdisc module specific attributes are allowed.
+.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
.B rtnetlink
is a new feature of Linux 2.2.
.SH BUGS
-This manual page is lacking and incomplete.
-.SH "SEE ALSO"
+This manual page is incomplete.
+.SH SEE ALSO
.BR cmsg (3),
.BR rtnetlink (3),
.BR ip (7),
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