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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
.\" $OpenBSD: inet.4,v 1.20 2019/10/30 10:39:53 jmc Exp $
.\" $NetBSD: inet.4,v 1.3 1994/11/30 16:22:18 jtc Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)inet.4 8.1 (Berkeley) 6/5/93
.\"
.Dd $Mdocdate: October 30 2019 $
.Dt INET 4
.Os
.Sh NAME
.Nm inet
.Nd Internet protocol family
.Sh SYNOPSIS
.In sys/types.h
.In netinet/in.h
.Sh DESCRIPTION
The Internet protocol family is a collection of protocols
layered atop the
.Em Internet Protocol
.Pq Tn IP
transport layer, and utilizing the Internet address format.
The Internet family provides protocol support for the
.Dv SOCK_STREAM ,
.Dv SOCK_DGRAM ,
and
.Dv SOCK_RAW
socket types; the
.Dv SOCK_RAW
interface provides access to the
.Tn IP
protocol.
.Sh ADDRESSING
Internet addresses are four byte quantities, stored in
network standard format.
The include file
.In netinet/in.h
defines this address as a discriminated union.
.Pp
Sockets bound to the Internet protocol family utilize
the following addressing structure,
.Bd -literal -offset indent
struct sockaddr_in {
u_int8_t sin_len;
sa_family_t sin_family;
in_port_t sin_port;
struct in_addr sin_addr;
int8_t sin_zero[8];
};
.Ed
.Pp
Sockets may be created with the local address
.Dv INADDR_ANY
to effect
.Dq wildcard
matching on incoming messages.
The address in a
.Xr connect 2
or
.Xr sendto 2
call may be given as
.Dv INADDR_ANY
to mean
.Dq this host .
The distinguished address
.Dv INADDR_BROADCAST
is allowed as a shorthand for the broadcast address on the primary
network if the first network configured supports broadcast.
.Sh PROTOCOLS
The Internet protocol family is comprised of
the
.Tn IP
transport protocol, Internet Control
Message Protocol
.Pq Tn ICMP ,
Transmission Control
Protocol
.Pq Tn TCP ,
and User Datagram Protocol
.Pq Tn UDP .
.Tn TCP
is used to support the
.Dv SOCK_STREAM
abstraction while
.Tn UDP
is used to support the
.Dv SOCK_DGRAM
abstraction.
A raw interface to
.Tn IP
is available
by creating an Internet socket of type
.Dv SOCK_RAW .
The
.Tn ICMP
message protocol is accessible from a raw socket.
.Pp
The 32-bit Internet address contains both network and host parts.
It is frequency-encoded; the most-significant bit is clear
in Class A addresses, in which the high-order 8 bits are the network
number.
Class B addresses use the high-order 16 bits as the network field,
and Class C addresses have a 24-bit network part.
Sites with a cluster of local networks and a connection to the
Internet may choose to use a single network number for the cluster;
this is done by using subnet addressing.
The local (host) portion of the address is further subdivided
into subnet and host parts.
Within a subnet, each subnet appears to be an individual network;
externally, the entire cluster appears to be a single, uniform
network requiring only a single routing entry.
Subnet addressing is enabled and examined by the following
.Xr ioctl 2
commands on a datagram socket in the Internet domain;
they have the same form as the
.Dv SIOCIFADDR
command (see
.Xr netintro 4 ) .
.Bl -tag -width SIOCSIFNETMASK
.It Dv SIOCSIFNETMASK
Set interface network mask.
The network mask defines the network part of the address;
if it contains more of the address than the address type would indicate,
then subnets are in use.
.It Dv SIOCGIFNETMASK
Get interface network mask.
.El
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr socket 2 ,
.Xr inet_net_ntop 3 ,
.Xr inet_ntop 3 ,
.Xr icmp 4 ,
.Xr ip 4 ,
.Xr netintro 4 ,
.Xr tcp 4 ,
.Xr udp 4
.Rs
.%T "An Introductory 4.3 BSD Interprocess Communication Tutorial"
.%B PS1
.%N 7
.Re
.Rs
.%T "An Advanced 4.3 BSD Interprocess Communication Tutorial"
.%B PS1
.%N 8
.Re
.Sh HISTORY
The
.Nm
protocol interface appeared in
.Bx 4.2 .
.Sh CAVEATS
The Internet protocol support is subject to change as
the Internet protocols develop.
Users should not depend on details of the current implementation, but rather
the services exported.
|
