🚀 go-pugleaf

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