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Date: Sun, 28 Nov 2004 22:28:05 +0000
From: David Malone <dwmalone@maths.tcd.ie>
To: Alin-Adrian Anton <aanton@spintech.ro>
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cc: Barney Wolff <barney@databus.com>
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Subject: Re: ssh & select() problem on 5.3
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On Sun, Nov 28, 2004 at 08:30:03PM +0200, Alin-Adrian Anton wrote:
> A tcpdump shows that what actually happens is that packets won't reach
> me in spite of the fact that his firewall(router)'s tcpdump shows that
> he keeps sending them to me. Packets never reach me, but I am still able
> to send them, by pressing ENTER on the ssh console.

It sounds very like a path MTU discovery problem then. I guess what
is happening is that large packets are being lost when sent along
this particular network path. Whatever is dropping them should send
a message saying "packet too big" and this will cause the machine
to send smaller packets in future. However either this message is
being dropped or not generated.

You can probably test this idea by using "ping -s <size>" or by
setting the MTU on the interface on your machine "ifconfig interface
mtu <size>". The real fix is to find out what's happened to the
"packet too big" ICMP message.

	David.