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List:       linux-hams
Subject:    Re: [AX25] unreleased sockets after disconnecting
From:       Thomas Osterried <thomas () osterried ! de>
Date:       2022-02-20 9:18:13
Message-ID: 6D71ECB7-775D-4D98-B856-C48B88E4DF7C () osterried ! de
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> Am 06.02.2022 um 22:12 schrieb Bernard Pidoux , f6bvp <f6bvp@free.fr>:
> 
> For long time it as been reported by many AX.25 users that connexions were \
> precluded after terminating a connexion with a remote station. 
> Some hamradio maintainers have been pretending not to be aware of such issue for \
> lacking proofs.

The problem is known. Iirc correctly, we have seen some approaches over the years to \
fix this issue. The last one I'd like to discuss is by YO2LOJ (Subject "NET/ROM bug \
fix from YO2LOJ?" in this list):

That patch is against the problem, that disconnected sessions still are listet, in \
"LISTENING" state'.

I'm not sure if it is exactly your problem, because in your /proc/net/ax25 example, \
those sessions seem to belong to iface "???" instead of "ax0".

I can reproduce (testet last week) is the following:
boot
configure ax25 iface
no userspace process started
connect from outside
disconnect from outside
-> 
netstat --ax25 shows that session in LISTEN state. In contrast to your output, it \
refers to the interface (not to "???").


The problem with the patch is, we observed a new, in my opinion unliked, behavior:
now a new connection is disconnected instantly (as long as no userspace daemon is \
listening). But there are protocols like "IP mode VC" need to be able to connect, \
even when no userspace daemon is running.

> I must restart my packet radio FPAC node (AX.25, ROSE and NetRom protocoles) every \
> other hour in order to let connexions available again for neighbours.

Perhaps you could try YO2LOJ's kernel patch and test if it helps for your urgent \
problem, or if there's another problem in the session-cleanup code.

> Here are some evidence from cat  /proc/net/ax25 showing old remnants of connexions \
> presumably there for ax25 sockets were not released. 
> 73 de Bernard, f6bvp

vy 73,
	- Thomas  dl9sau


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