1 .\" Copyright (c) 1983, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\" 3. Neither the name of the University nor the names of its contributors
13 .\" may be used to endorse or promote products derived from this software
14 .\" without specific prior written permission.
16 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 .\" @(#)udp.4 8.1 (Berkeley) 6/5/93
36 .Nd Internet User Datagram Protocol
42 .Fn socket AF_INET SOCK_DGRAM 0
45 is a simple, unreliable datagram protocol which is used
48 abstraction for the Internet
51 sockets are connectionless, and are
52 normally used with the
58 call may also be used to fix the destination for future
59 packets (in which case the
67 system calls may be used).
70 address formats are identical to those used by
74 provides a port identifier in addition
75 to the normal Internet address format.
79 space is separate from the
90 packets may be sent (assuming the underlying network supports
91 this) by using a reserved
92 .Dq broadcast address ;
94 is network interface dependent.
98 transport level may be used with
105 protocol implements a number of variables in the
110 .Bl -tag -width UDPCTL_RECVSPACEX
113 Enable udp checksums (enabled by default).
116 Maximum outgoing UDP datagram size
119 Maximum space for incoming UDP datagrams
121 For all udp datagrams, to ports on which there is no socket
122 listening, log the connection attempt (disabled by default).
124 When a datagram is received on a port where there is no socket
125 listening, do not return an ICMP port unreachable message.
126 (Disabled by default.
131 A socket operation may fail with one of the following errors returned:
134 when trying to establish a connection on a socket which
135 already has one, or when trying to send a datagram with the destination
136 address specified and the socket is already connected;
138 when trying to send a datagram, but
139 no destination address is specified, and the socket has not been
142 when the system runs out of memory for
143 an internal data structure;
146 is made to create a socket with a port which has already been
148 .It Bq Er EADDRNOTAVAIL
149 when an attempt is made to create a
150 socket with a network address for which no network interface