Telnet Disconnects - Please help! [SOLVED]

[Harald Milz]

>>> echo 0>/proc/sys/net/ipv4/tcp_window_scaling
>>> 
>>> If window scaling is not negotiated properly, then you will experience
>>> "freezing" on receiving large amounts of output from the router or
>>> switch.
>> 
>> But it doesn't freeze. The connection is terminated abruptly. Or did I
>> misunderstand the OP's description? (which I no longer have).
> 
> My only point is you can turn window scaling off on the GNU/Linux box
> and see if the problem goes away.  If it does, then that is the source
> of the problem.  If not, it at least eliminates it as an issue.
> 
> I experienced the "freezing" issue with a hotel ISP which evidently had
> switches or routers which did not negotiate window scaling correctly or
> at all.  It took me several hours to figure out what was going on.  I
> tracked down the problem by using tcpdump and watching the packets go
> by.  My TCP keep sending timeout ACKS, while the remote TCP refused to
> send anything. I suspect the remote end thought my TCP's receive window
> was zero, even though my TCP kept telling it the receive window was wide
> open. The window scaling interfered with the TCP negotiation in some
> peculiar way.  I suspect it was an old implementation which did not
> support window scaling at all and ignored the initial negotiation.
> -- 
> Smoot Carl-Mitchell

Guys, thank you for the help.

echo 0> /proc/sys/net/ipv4/tcp_window_scaling

The above command solved the issue. I am unable to determine if this is caused because of some old router, incompatibility with MPLS Tunnels, etc.

I have posted the solution along BUG 228953 at Launchpad, along with a Special Thanks to you guys.

Kindest regards,

Harald
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