And import of the x25-utils software package, whihc was created as user-space tools for using the linux-kernel X.25 implementation.
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README import x25_utils-2.3.93.tar.gz 2023-08-29 20:26:18 +02:00


X.25 Utilities 2.3.93

This is basically identical to the previous 2.1.20 release. It mainly
includes changes to compile and link with glibc2. x25trace also has some
added functionality. See the Changes file for details.

The x25 telnet[d] programs now compile and link against glibc2 and ncurses
by means of some (ugly) hacks. They should work with all 2.2.x kernels
as well as 2.4.0-test12 and newer. But be aware that these programs are
only intended for testing linux-x25. They don't implement any
established standard for communicating over X.25. They are based on
old versions of bsd telnet[d]. In particular, they do not contain any
security related fixes that might have been included in recent bsd

Henner  (

Old README file contents follow:

These are some knocked up utilities to support the X.25 code within the
Linux kernel. The programs x25route and x25trace are new and do what they
say they mean, the telnet and telnetd are crude hacks of BSD telnet and
telnetd to run over X.25 instead of IP.

To build the X.25 Utilities

In this directory type:


and everything should build. Do *not* do a "make install" as the X.25
versions of telnet and telnetd will possibly overwrite the standard TCP/IP
versions on your machine. It is probably best to run these two programs from
where they are built to be safe. The x25route and x25trace programs along
with their manual pages can be installed safetly though.

All of the utilities have a manual page, although the telnet and telnetd
programs only have the standard BSD pages.

To start up X.25 under Linux

First start up your LAPB interface. At present the only such interface is
the LAPB over ethernet device. Firstly get your ethernet card up and running
as normal using ifconfig.

Next bring up the lapb0 device with:

ifconfig lapb0 up

Next set up your X.25 routes. I would guess at this stage you just want all
X.25 packets to go out via via lapb0, so just do:

x25route add 1/0 lpab0

To make sure its all OK do:

cat /proc/net/x25*

You will see alsorts of useless information !

To set up an X.25 TELNET link, start up telnetd on the remote machine with
the command:

./telnetd <address>

Where <address> is the X.121 address that you want telnetd to listen on.

On the local machine use the command:

./telnet <locaddr> <remaddr>

Where <locaddr> is the local X.121 address to be used for the outgoing
connection, and <remaddr> is the X.121 address of the remote copy of

If you are running Linux/X.25 to another machine running Linux/X.25 without
an intermediate machine operating as a DCE, it will not work. What you need
to do is build *one* of your machines with the LAPB layer operating as a DCE.
To do this edit the linux/include/net/lapb.h and change the line:




and rebuild your kernel. I hope that this will be a run-time option
eventually, but at the moment this is the only way to do it.

The Future

A lot still needs to be done. I have implemented the bulk of the things that
make up X.25, although it is not well tested. What still needs to be done is
more work on configuring X.25, especially addresses, what mechanism do we
use to inform the kernel what X.121 address(es) it is to use ? More work
needs doing on the X.25 PLP/LAPB interaction to allow for the run-time
setting of parameters. How are these parameters stored ? Much to do I fear.

In the short term we could do with some "real" X.25 applications being
ported across. There is source code on the net for such things as PAD,
NIFTP, X.29 and well as ISODE that all need to be made to work the kernel
code. Any takers ?