1 .\" This man page is Copyright (C) 1998 Heiner Eisen.
2 .\" Permission is granted to distribute possibly modified copies
3 .\" of this page provided the header is included verbatim,
4 .\" and in case of nontrivial modification author and date
5 .\" of the modification is added to the header.
6 .\" $Id: x25.7,v 1.4 1999/05/18 10:35:12 freitag Exp $
7 .TH X25 7 2008-08-08 "Linux" "Linux Programmer's Manual"
9 x25, AF_X25 \- ITU-T X.25 / ISO-8208 protocol interface.
11 .B #include <sys/socket.h>
13 .B #include <linux/x25.h>
15 .B x25_socket = socket(AF_X25, SOCK_SEQPACKET, 0);
17 X25 sockets provide an interface to the X.25 packet layer protocol.
18 This allows applications to
19 communicate over a public X.25 data network as standardized by
20 International Telecommunication Union's recommendation X.25
22 X25 sockets can also be used for communication
23 without an intermediate X.25 network (X.25 DTE-DTE mode) as described
26 Message boundaries are preserved \(em a
29 retrieve the same chunk of data as output with the corresponding
32 When necessary, the kernel takes care
33 of segmenting and reassembling long messages by means of
35 There is no hard-coded upper limit for the
37 However, reassembling of a long message might fail if
38 there is a temporary lack of system resources or when other constraints
39 (such as socket memory or buffer size limits) become effective.
41 occurs, the X.25 connection will be reset.
45 socket address family uses the
46 .I struct sockaddr_x25
47 for representing network addresses as defined in ITU-T
53 sa_family_t sx25_family; /* must be AF_X25 */
54 x25_address sx25_addr; /* X.121 Address */
62 to be interpreted as a null-terminated string.
63 .I sx25_addr.x25_addr[]
64 consists of up to 15 (not counting the terminating 0) ASCII
65 characters forming the X.121 address.
66 Only the decimal digit characters from \(aq0\(aq to \(aq9\(aq are allowed.
68 The following X.25-specific socket options can be set by using
78 Controls whether the X.25 Q-bit (Qualified Data Bit) is accessible by the
80 It expects an integer argument.
81 If set to 0 (default),
82 the Q-bit is never set for outgoing packets and the Q-bit of incoming
84 If set to 1, an additional first byte is prepended
85 to each message read from or written to the socket.
87 the socket, a 0 first byte indicates that the Q-bits of the corresponding
88 incoming data packets were not set.
89 A first byte with value 1 indicates
90 that the Q-bit of the corresponding incoming data packets was set.
91 If the first byte of the data written to the socket is 1 the Q-bit of the
92 corresponding outgoing data packets will be set.
93 If the first byte is 0
94 the Q-bit will not be set.
96 The AF_X25 protocol family is a new feature of Linux 2.2.
98 Plenty, as the X.25 PLP implementation is
99 .BR CONFIG_EXPERIMENTAL .
101 This man page is incomplete.
103 There is no dedicated application programmer's header file yet;
104 you need to include the kernel header file
106 .B CONFIG_EXPERIMENTAL
107 might also imply that future versions of the
108 interface are not binary compatible.
110 X.25 N-Reset events are not propagated to the user process yet.
112 if a reset occurred, data might be lost without notice.
117 Jonathan Simon Naylor:
118 \(lqThe Re-Analysis and Re-Implementation of X.25.\(rq
121 .I ftp://ftp.pspt.fi/pub/ham/linux/ax25/x25doc.tgz