[nos-bbs] ugly ax25 linux bug ? no idea SAMB gets 2 UA replies ...

[M Langelaar]

This is a bit technical, but I have stumbled across a problem where if I
connect to a node that depends on AX25 Linux stack I am receiving 2
UA to my SABM, the first UA JNOS takes and moves it to LAPB_CONNECTED,
but the second UA JNOS takes and tries to re-establish the link and 
instantly
we get a loop of SABM / UA over and over, just loops and does not stop, 
basically
creating a DOS attack. It's unreal to watch.

My instant fix for this (and I confirm it works) is to ignore UA FRMR if 
we are
in a LAPB_CONNECTED state, which probably it should. I can fix that on my
end no problem. I can't find in the AX25 specs what a system should do it it
receives a UA while in LAPB_CONNECTED, but I never see that situation ever
happen until recently.

Is anyone aware of an AX25 utils or linux libs bug that might be causing 
this ?

Maiko / VE4KLM