1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" FIXME The following socket options are yet to be documented
.\"
.\" IP_XFRM_POLICY (2.5.48)
.\" Needs CAP_NET_ADMIN
.\"
.\" IP_IPSEC_POLICY (2.5.47)
.\" Needs CAP_NET_ADMIN
.\"
.\" IP_MINTTL (2.6.34)
.\" commit d218d11133d888f9745802146a50255a4781d37a
.\" Author: Stephen Hemminger <shemminger@vyatta.com>
.\"
.\" MCAST_JOIN_GROUP (2.4.22 / 2.6)
.\"
.\" MCAST_BLOCK_SOURCE (2.4.22 / 2.6)
.\"
.\" MCAST_UNBLOCK_SOURCE (2.4.22 / 2.6)
.\"
.\" MCAST_LEAVE_GROUP (2.4.22 / 2.6)
.\"
.\" MCAST_JOIN_SOURCE_GROUP (2.4.22 / 2.6)
.\"
.\" MCAST_LEAVE_SOURCE_GROUP (2.4.22 / 2.6)
.\"
.\" MCAST_MSFILTER (2.4.22 / 2.6)
.\"
.\" IP_UNICAST_IF (3.4)
.\" commit 76e21053b5bf33a07c76f99d27a74238310e3c71
.\" Author: Erich E. Hoover <ehoover@mines.edu>
.\"
.TH IPPROTO_IP 2const 2026-01-05 "Linux man-pages (unreleased)"
.SH NAME
IPPROTO_IP
\-
Linux IPv4 protocol socket options
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.BR "#include <netinet/in.h>" " /* Definition of " IP* " constants */"
.B #include <sys/socket.h>
.P
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IP,\~int\~ opt ,
.BI " const\~void\~" val [ size ],\~size_t\~ size );
.BI int\~getsockopt(int\~ sockfd ,\~IPPROTO_IP,\~int\~ opt ,
.BI " void\~" val [ size ],\~size_t\~ size );
.fi
.SH DESCRIPTION
IP supports some protocol-specific socket options that can be set with
.BR setsockopt (2)
and read with
.BR getsockopt (2).
The socket option level for IP is
.BR IPPROTO_IP .
.\" or SOL_IP on Linux
.P
The following socket options are supported.
.TP
.BR IP_ADD_MEMBERSHIP (2const)
.TQ
.BR IP_ADD_SOURCE_MEMBERSHIP (2const)
.TQ
.BR IP_BIND_ADDRESS_NO_PORT (2const)
.TQ
.BR IP_BLOCK_SOURCE (2const)
.TQ
.BR IP_DROP_MEMBERSHIP (2const)
.TQ
.BR IP_DROP_SOURCE_MEMBERSHIP (2const)
.TQ
.BR IP_FREEBIND (2const)
.TQ
.BR IP_HDRINCL (2const)
.TQ
.BR IP_LOCAL_PORT_RANGE (2const)
.TQ
.BR IP_MSFILTER (2const)
.TQ
.BR IP_MTU (2const)
.TQ
.BR IP_MTU_DISCOVER (2const)
.TQ
.BR IP_MULTICAST_ALL (2const)
.TQ
.BR IP_MULTICAST_IF (2const)
.TQ
.BR IP_MULTICAST_LOOP (2const)
.TQ
.BR IP_MULTICAST_TTL (2const)
.TQ
.BR IP_NODEFRAG (2const)
.TQ
.BR IP_OPTIONS (2const)
.TQ
.BR IP_PASSSEC (2const)
.TQ
.BR IP_PKTINFO (2const)
.TQ
.BR IP_RECVERR (2const)
.TQ
.BR IP_RECVOPTS (2const)
.TQ
.BR IP_RECVORIGDSTADDR (2const)
.TQ
.BR IP_RECVTOS (2const)
.TQ
.BR IP_RECVTTL (2const)
.TQ
.BR IP_RETOPTS (2const)
.TQ
.BR IP_ROUTER_ALERT (2const)
.TQ
.BR IP_TOS (2const)
.TQ
.BR IP_TRANSPARENT (2const)
.TQ
.BR IP_TTL (2const)
.TQ
.BR IP_UNBLOCK_SOURCE (2const)
.SH ERRORS
See
.BR setsockopt (2).
See
.BR ip (7).
.TP
.B ENOPROTOOPT
.I opt
is invalid.
.\" .SH STANDARDS
.\" IP_XFRM_POLICY is Linux-specific
.\" IP_IPSEC_POLICY is a nonstandard extension, also present on some BSDs
.SH HISTORY
.TP
.B IPPROTO_IP
POSIX.1-2001.
.SH SEE ALSO
.BR setsockopt (2),
.BR ip (7)
|
