Anders.Klemets@cs.cmu.edu (06/24/91)
Archive-name: internet/tunnel/axip/1991-06-24 Archive: thumper.bellcore.com:/pub/ka9q/incoming/axip.arc [128.96.41.1] Original-posting-by: Anders.Klemets@cs.cmu.edu Original-subject: AX.25 on top of IP Reposted-by: emv@msen.com (Edward Vielmetti, MSEN) I have implemented Brians RFC-1226 for transmitting AX.25 frames over IP in NOS. Apparently nobody else has done it for NOS yet? The code is pretty simple since parts of it was already there. For instance, the code for calculating the HDLC checksum was already in the file ppp.c. (Although I am not perfectly sure that I am generating the right FCS.) To make the AX.25/IP code more useful I also added a tiny piece of code that implements crossband digipeating. Here is how to use it. Suppose that I am running NOS with the callsign SK0WE-2 on the radio interface. I want to setup a wormhole with w1xxx.foo.com. I will then have to type: attach axip ai0 256 w1xxx.foo.com sk0we-3 where "ai0" is the name of my new 'wormhole' interface. "256" is the MTU for AX.25. "w1xxx.foo.com" is the hostname of my peer. "sk0we-3" is an optional callsign of this new interface. The crossband digipeating to my radio interface would not work if I did not specify a callsign (other than sk0we-2.) That is all. Assuming that w1xxx has done a corresponding setup, I can now type connect ai0 w1zyx w1xxx-2 and the AX.25 frames will be sent to w1xxx.foo.com, where he will digipeat them on the w1xxx-2 interface, which hopefully is the 2m port. As long as both I and w1xxx use different callsigns on the radio and wormhole ports crossband digipeating is supported. One of the local TNC users will then be able to type Connect w1zyx Via sk0we-3, w1xxx-2 There is also a sequrity feature: The code will ignore AX.25 frames received from IP hosts that have not previously been enabled with the "attach axip" command. The changed source files are available at thumper.bellcore.com as pub/ka9q/incoming/axip.arc. 73, Anders -- MSEN Archive Service file verification thumper.bellcore.com -rw-rw-rw- 1 61 61 40427 Jun 24 09:27 /pub/ka9q/incoming/axip.arc found axip ok thumper.bellcore.com:/pub/ka9q/incoming/axip.arc