nullmodem

nullmodem - a Utility to loopback Pseudo-Terminals The Story Don't you know the problem? 1.) You are programming some software that connects to the serial interface of your computer (e.g. some modem software) and you want to test your software without any modem (because it's already in use, isn't it?). So you need two computers and a so called nullmodem with TXD and RXD lines crossed. But you can do it in a much better way, because you've got a Linux machine: You can connect two equal instances of your program with this nullmodem utility. 2.) You have a connection problem with Pseudo-Terminals (ptys) where one program should connect to an existing pty, but you want to start and stop the program that opens the pty-master. So you need some kind of an adapter: nullmodem. My Application
my application of nullmodem I'm using nullmodem for my packet-radio station to connect a softmodem with the linux kernel using the KISS protocol. This has the advantage that it's possible to exchange/restart the softmodem without terminating the level-2 (AX.25) connection of the transmission protocol. This is very advantageous if you play with some parameters of a softmodem. I'm even using nullmodem for a pure loopback based on the KISS protocol. So I can initiate connections to my own computer without going "on air". nullmodem can be seen as a generalization of Frederic Rible's (F1OAT) kissnetd that is optimized to transport KISS packets. If you know some other applications of this program, please let me know. Maybe it's possible to use nullmodem for a local SLIP loopback - but I've not tested this.
Documentation
For documentation look at the man page of nullmodem.
ChangeLog
nullmodem 0.0.4 - Wed, 3 Aug 2005 20:16:59 +0200 a few cleanups nullmodem 0.0.3 - Sat, 24 Jul 2004 18:31:44 +0200 many code cleanups and improvements by J. Carter: class{}ified program using STL containers added lock files more cleanups and improvements by my: added --setuid --setgid options some latency improvements nullmodem 0.0.2-1 - Sun, 10 Aug 2003 19:58:23 +0200 updated to debian Standards-Version: 3.6.0 nullmodem 0.0.2 - Fri, 21 Mar 2003 08:35:01 +0100 small fixes for g++-3.2 nullmodem 0.0.1 - Wed, 6 Nov 2002 21:00:01 +0100 Initial Release.
Download
license: GPL source package nullmodem-0.0.4.tar.gz, 309k, 2006-Mar-28 old versions I've prepared a debian package for this program. You can download this via apt-get update; apt-get install nullmodem if you configure your system to include my debian repository.
Published on
nullmodem is listed on freshmeat there is a link on linuxlinks.com