'\" t
.\" Don't change the first line, it tells man that tbl is needed.
.\" This man page is Copyright (c) 1998 by Andi Kleen. Subject to the GPL.
.\" Based on the original comments from Alexey Kuznetsov
.\" $Id: netlink.7,v 1.8 2000/06/22 13:23:00 ak Exp $
.\"
.\" Japanese Version Copyright (c) 1999 NAKANO Takeo all rights reserved.
.\" Translated 1999-12-06 by NAKANO Takeo <nakano@apm.seikei.ac.jp>
.\" Updated 2001-04-04 by Yuichi SATO <ysato@h4.dion.ne.jp>, catch up to LDP v1.35
.\" Updated 2006-06-23 by Yuichi SATO <ysato444@yahoo.co.jp>, catch up to LDP v2.29
.\"
.\"WORD		payload		ڥ
.\"WORD		capability	
.\"
.TH NETLINK  7 2008-11-11 "Linux" "Linux Programmer's Manual"
.SH ̾
netlink \- ͥȥ桼֤̿ (AF_NETLINK)
.SH 
.nf
.B #include <asm/types.h>
.B #include <sys/socket.h>
.B #include <linux/netlink.h>

.BI "netlink_socket = socket(AF_NETLINK, " socket_type ", " netlink_family );
.fi
.SH 
netlink ϥͥ⥸塼ȥ桼֤Υץ֤
Ȥꤹ뤿Ѥ롣
netlink ϡ桼ץФƤ
ɸŪʥåȥ١Υ󥿡ե
ͥ⥸塼ˤϥͥ API 󶡤롣
ͥΥ󥿡եˤĤƤϤ man ڡǤϵҤʤ
ޤnetlink 饯ǥХѤ
obsolete  netlink 󥿡ե⤢뤬⤳ʸǤϲ⤷ʤ
ñ˲ߴΤѰդƤΤˤʤ

netlink ϥǡظΥӥǤ롣
.I socket_type
ˤ
.B SOCK_RAW

.B SOCK_DGRAM
ξȤǽǤ롣
 netlink ץȥϥǡ raw åȤζ̤򤷤ʤ

.I netlink_family
ϡ̿륫ͥ⥸塼 netlink 롼פѤ롣
߳ƤƤ netlink եߥ꡼ϰʲ̤ꡣ
.TP
.B NETLINK_ROUTE
롼ƥ󥰤ȥ󥯤ι롣
(IPv4  IPv6 ξ) 롼ƥ󥰥ơ֥롦
IP ɥ쥹󥯥ѥ᡼˵ (neighbor setup)
塼󥰥롼 (queueing dicipline)ȥեå饹
ѥåȤΥ饹ʬνѤ뤳ȤǤ
.RB ( rtnetlink (7)
򸫤)
.TP
.B NETLINK_W1
ñ (1-wire) Υ֥ƥफΥå
.TP
.B NETLINK_USERSOCK
桼⡼ɥåȥץȥΤͽ󤵤Ƥ롣
.TP
.B NETLINK_FIREWALL
IPv4 ѥåȤ netfilter 桼֤ž롣
.I ip_queue
ͥ⥸塼ǻѤ롣
.TP
.B NETLINK_INET_DIAG
.\" FIXME More details on NETLINK_INET_DIAG needed.
INET åȤ˥󥰤롣
.TP
.B NETLINK_NFLOG
Netfilter/iptables ULOG.
.TP
.B NETLINK_XFRM
.\" FIXME More details on NETLINK_XFRM needed.
IPsec.
.TP
.B NETLINK_SELINUX
SELinux Υ٥Ρ
.TP
.B NETLINK_ISCSI
.\" FIXME More details on NETLINK_ISCSI needed.
Open-iSCSI.
.TP
.B NETLINK_AUDIT
.\" FIXME More details on NETLINK_AUDIT needed.
ƺ (audit) Ԥ
.TP
.B NETLINK_FIB_LOOKUP
.\" FIXME More details on NETLINK_FIB_LOOKUP needed.
桼֤ FIB ååפ˥롣
.TP
.B NETLINK_CONNECTOR
ͥ륳ͥ
ܤϥͥ륽
.I Documentation/connector/*
򻲾Ȥ뤳ȡ
.TP
.B NETLINK_NETFILTER
.\" FIXME More details on NETLINK_NETFILTER needed.
netfilter ֥ƥࡣ
.TP
.B NETLINK_IP6_FW
IPv6 ѥåȤ netfilter 桼֤ž롣
.I ip6_queue
ͥ⥸塼ǻѤ롣
.TP
.B NETLINK_DNRTMSG
DECnet 롼ƥ󥰥å
.TP
.B NETLINK_KOBJECT_UEVENT
.\" FIXME More details on NETLINK_KOBJECT_UEVENT needed.
桼֤ؤΥͥå
.TP
.B NETLINK_GENERIC
netlink ñ˻Ѥ뤿ΰŪ netlink եߥ꡼
.PP
netlink åϥХȥȥ꡼फʤꡢ
İʾ
.I nlmsghdr
إåȡбڥ (payload) ޤޤ롣
Хȥȥ꡼ˤϡɸ
.B NLMSG_*
ޥˤäƤΤߥ٤Ǥ롣
ܤ
.BR netlink (3)
򸫤衣

ޥѡȥå (İʾ
.I nlmsghdr
إåȡбڥɤ
ĥХȥȥ꡼˴ޤޤ) ˤƤϡ
ƬΥإå³Υإåˤ
.B NLM_F_MULTI
ե饰åȤ롣ǸΥإå㳰ǡ
.B NLMSG_DONE
פȤʤ롣

줾
.B nlmsghdr
θˤϥڥɤ³

.in +4n
.nf
struct nlmsghdr {
    __u32 nlmsg_len;    /* إåޤåĹ */
    __u16 nlmsg_type;   /* åƤΥ */
    __u16 nlmsg_flags;  /* ɲåե饰 */
    __u32 nlmsg_seq;    /* ֹ */
    __u32 nlmsg_pid;    /* ץ PID */
};
.fi
.in

.I nlmsg_type
ɸΥåפΤɤ줫ĤǤ:
.B NLMSG_NOOP
å̵뤵롣
.B NLMSG_ERROR
åϥ顼򼨤ڥɤˤ
.I nlmsgerr
¤Τ롣
.B NLMSG_DONE
åϥޥѡȥåνλ롣

.in +4n
.nf
struct nlmsgerr {
    int error;        /* ޤ 0  errno ϱɽ */
    struct nlmsghdr msg;  /* 顼򵯤åΥإå */
};
.fi
.in

 netlink եߥ꡼ǻǤåפϡ
̾ä¿˴ؤƤŬڤ man ڡ򸫤Ƥۤ
Ȥ
.B NETLINK_ROUTE
˴ؤƤ
.BR rtnetlink (7)
˽񤤤Ƥ롣

.I nlmsg_flags
ɸե饰ӥå
.br
---------------------------------
.TS
tab(:);
lB l.
NLM_F_REQUEST:׵åƤǥåȤʤФʤʤ
NLM_F_MULTI:T{
ΥåϥޥѡȥåΰǤ롣
ޥѡȥå
.B NLMSG_DONE
ǽü롣
T}
NLM_F_ACK:α׵᤹롣
NLM_F_ECHO:׵򥨥롣
.TE

GET ׵ˤɲåե饰ӥå
.br
-------------------------------------
.TS
tab(:);
lB l.
.\" FIXME NLM_F_ATOMIC is not used any more?
NLM_F_ROOT:ñΥȥǤϤʤơ֥Τ֤
NLM_F_MATCH:T{
åƤϤ줿 (criteria) ˥ޥå
ƤΥȥ֤
ޤƤʤ
T}
NLM_F_ATOMIC:ơ֥ΥȥߥåʥʥåץåȤ֤
NLM_F_DUMP:ʥޥ(NLM_F_ROOT|NLM_F_MATCH) Ʊ
.TE

.B NLM_F_ATOMIC
Ȥϡ
.B CAP_NET_ADMIN
¤Ĥ¸桼 ID  0 ǤʤФʤʤդ뤳ȡ

NEW ׵ˤɲåե饰ӥå
.br
-------------------------------------
.TS
tab(:);
lB l.
NLM_F_REPLACE:¸Υ֥Ȥִ롣
NLM_F_EXCL:Ǥ˥֥Ȥäִʤ
NLM_F_CREATE:ޤ֥Ȥʤк롣
NLM_F_APPEND:֥ȥꥹȤκǸɲä롣
.TE

.I nlmsg_seq

.I nlmsg_pid
ϥåפ˻Ѥ롣
.I nlmsg_pid
ϥåɽ
å netlink åȤƤ硢
.I nlmsg_pid
ȥץ PID  1:1 δطǤϤʤդ뤳ȡ
ܤϡ
.RB  ɥ쥹Υեޥå 
Υ򻲾Ȥ뤳ȡ

.I nlmsg_seq

.I nlmsg_pid
 netlink Υˤϸʤ (opaque)

netlink Ͽι⤤ץȥǤϤʤ
netlink ϥåԤϤ뤿˺Ԥ
꤬­ʤäꥨ顼äꤹ
åꤳܤȤ⤢롣
ι⤤žԤȤϡ
ԤϼԤ˱׵᤹뤳ȤǤ롣
ˤ
.B NLM_F_ACK
ե饰򥻥åȤ롣

.B NLMSG_ERROR
ѥåȤΥ顼եɤ 0 ˤΤˤʤ롣
ץꥱϼʬȤΥåȤˤϡ
ʤФʤʤ
ͥϼԤѥåȤФơ
.B NLMSG_ERROR
åȤ롣
桼ץϤδˤ⽾ɬפ롣

ɤΤ褦ʾǤ⥫ͥ뤫桼ؤ
ι⤤žԲǽǤ롣
åȥХåեդξ硢ͥ netlink åǤʤ
åϼꤳܤơͥȥ桼֥ץϡ
ͥξ֤ˤĤƤƱӥ塼ĤȤǤʤʤ롣
줬ä
.RB ( recvmsg (2)
ˤä
.B ENOBUFS
顼֤) ΤƺƤƱΤϡ
ץꥱǤǤ롣
.SS ɥ쥹Υեޥå
.I sockaddr_nl
¤Τϥ桼֤䥫֤ͥ netlink 饤Ȥ򵭽Ҥ롣
.I sockaddr_nl
ϥ˥㥹 (ñ³ˤ) ˤǤ뤷
netlink ޥ㥹ȥ롼
.RI ( nl_groups
 0 Ǥʤ) ˤ뤳ȤǤ롣

.in +4n
.nf
struct sockaddr_nl {
    sa_family_t     nl_family;  /* AF_NETLINK */
    unsigned short  nl_pad;     /* 0 Ǥ */
    pid_t           nl_pid;     /* ץ ID */
    __u32           nl_groups;  /* ޥ㥹ȥ롼ץޥ */
};
.fi
.in

.I nl_pid
 netlink åȤΥ˥㥹ȥɥ쥹Ǥ롣
Ԥ褬ͥξϡ 0 Ǥ롣
桼֥ץξ硢̾
.I nl_pid
ϹԤΥåȤͭƤץ PID Ǥ롣

.I nl_pid
ϥץǤϤʤ netlink åȤƱꤹ롣
ץʣ netlink åȤͭ硢
.I nl_pid
ϺǤĤΥåȤΥץ ID Ȥʤʤ
.I nl_pid
 netlink åȤ˳Ƥˡ 2 Ĥ롣
ץꥱ
.BR bind (2)
Ƥ
.I nl_pid
ꤹ硢
.I nl_pid
դǤ뤳ȤǧΤϥץꥱǤȤʤ롣
ץꥱ
.I nl_pid
 0 ꤷ硢ͥ뤬ͤƤ롣
ͥϥץǽ˥ץ󤷤
netlink åȤФƥץ ID ơ
ʹߤ˥ץƤ netlink åȤˤդ
.I nl_pid
Ƥ롣

.I nl_groups
ϥӥåȥޥǡ٤ƤΥӥåȤ netlink 롼ֹɽ
줾 netlink եߥ꡼ 32 Υޥ㥹ȥ롼פΥåȤġ
줾 netlink եߥ꡼ 32 Υޥ㥹ȥ롼פ
åȤġ
.BR bind (2)
åȤФƸƤФȡ
.I sockaddr_nl

.I nl_groups
եɤˤ listen 롼פΥӥåȥޥåȤ롣
ǥեȤͤ 0 ǡޥ㥹Ȥڼʤ
.BR sendmsg (2)

.BR connect (2)
ˤäơ륽åȤåޥ㥹ȤȤϡ
.I nl_groups
롼פΥӥåȥޥ򥻥åȤФ褤
¸桼 ID  0 
.B CAP_NET_ADMIN
¤ĥ桼Τߤ netlink ޥ㥹ȥ롼פ
ꡢ listen ꤹ뤳ȤǤ롣
ޥ㥹ȥ롼׸å硢Ф
 PID ȥޥ㥹ȥ롼פȤ֤٤Ǥ롣
.SH С
netlink ؤΥåȥ󥿡ե Linux 2.2 οǽǤ롣

Linux 2.0 ϡäȸŪʥǥХ١ netlink 󥿡ե
ݡȤƤ (ߴΤ˺ǤѤǤ)
Ť󥿡ե˴ؤƤϤǤϵҤʤ

NETLINK_SELINUX  Linux 2.6.4 о줷

NETLINK_AUDIT  Linux 2.6.6 о줷

NETLINK_KOBJECT_UEVENT  Linux 2.6.10 о줷

NETLINK_W1, NETLINK_FIB_LOOKUP  Linux 2.6.13 о줷

NETLINK_INET_DIAG, NETLINK_CONNECTOR, NETLINK_NETFILTER 
Linux 2.6.14 о줷

NETLINK_GENERIC, NETLINK_ISCSI  Linux 2.6.15 о줷
.SH 
٥Υͥ륤󥿡եꡢ
.I libnetlink
ޤ
.I libnl
̤ netlink ѤۤɤȤ¿
.SH Х
 man ڡϴƤʤ
.SH 
ʲǤϡ
.B RTMGRP_LINK
(ͥåȥ󥿡ե create/delete/up/down ٥) 
.B RTMGRP_IPV4_IFADDR
(IPv4 ɥ쥹 add/delete ٥) ޥ㥹ȥ롼פ listen 
.B NETLINK_ROUTE
netlink Ƥ롣

.in +4n
.nf
struct sockaddr_nl sa;

memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR;

fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
bind(fd, (struct sockaddr *) &sa, sizeof(sa));
.fi
.in

Ǥϡnetlink å򥫡ͥ (pid 0) ˡ򼨤Ƥ롣
פݤο뤿ˡץꥱ
åΥֹʤФʤʤդ뤳ȡ

.in +4n
.nf
struct nlmsghdr *nh;    /*  nlmsghdr ȥڥ */
struct sockaddr_nl sa;
struct iovec iov = { (void *) nh, nh\->nlmsg_len };
struct msghdr msg;

msg = { (void *)&sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
nh\->nlmsg_pid = 0;
nh\->nlmsg_seq = ++sequence_number;
/* NLM_F_ACK ꤹ뤳Ȥǡͥ˱׵᤹ */
nh\->nlmsg_flags |= NLM_F_ACK;

sendmsg(fd, &msg, 0);
.fi
.in

Ǹϡnetlink åɤ߹ߤǤ롣

.in +4n
.nf
int len;
char buf[4096];
struct iovec iov = { buf, sizeof(buf) };
struct sockaddr_nl sa;
struct msghdr msg;
struct nlmsghdr *nh;

msg = { (void *)&sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
len = recvmsg(fd, &msg, 0);

for (nh = (struct nlmsghdr *) buf; NLMSG_OK (nh, len);
     nh = NLMSG_NEXT (nh, len)) {
    /* ޥѡȥåν */
    if (nh\->nlmsg_type == NLMSG_DONE)
        return;

    if (nh\->nlmsg_type == NLMSG_ERROR)
        /* 餫Υ顼Ԥ */
    ...

    /* ڥɤβϤ³ */
    ...
}
.fi
.in
.SH Ϣ
.BR cmsg (3),
.BR netlink (3),
.BR capabilities (7),
.BR rtnetlink (7)
.PP
libnetlink ˴ؤ
ftp://ftp.inr.ac.ru/ip-routing/iproute2*

libnl ˴ؤ
http://people.suug.ch/~tgr/libnl/

RFC 3549 "Linux Netlink as an IP Services Protocol"