session timeout.

this is a kernel setting, AFAIK in /proc/sys/net/ipv4/tcp_keepalive_time
default is 2 houres (7200 seconds), usually
You may change it like:

echo 14200 > /proc/sys/net/ipv4/tcp_keepalive_time

I don't think the tcp_keepalive_time is what's causing the telnet timeouts. I've had open telnet session between my 7.1 boxes for days on occasion. I'd suspect that there's something between the windows client and the Lnix system that's got an idle timer, like a firewall. Also be aware that the default bash shell doesn't have an idle timer, but tcsh does.

.. tcp_keepalive_time could be one reason, autologout in tcsh another, and so on ...
I agree with jlevie, (UNIX's) TCP/IP has no timeout usualy, unless the OS specifies one (like Solaris).

I tried with tcp_keepalive_time and it did not work. Any other option, regarding setting up under Windows, I dont think there is any settings under windows, if there is any let me know.

Also, session timeouts on masqueraded/NAT connections can do this as well (at least, that's what always kills _my_ ssh sessions ;-).

Just another thing to check.

-Jon

Use Putty:

ftp://ftp.chiark.greenend.org.uk/users/sgtatham/putty-latest/putty.exe

BTW, M$ telnet is buggy.
Also give TeraTerm a try (supports ssh too).
  http://hp.vector.co.jp/authors/VA002416/teraterm.html

vatsasri:
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keep alive options won't help if the kernel drops the connection, that's what the kernel thing is for ;-)

Daaaaaamn - that was open so long my comment became irrelevant (with the advent of iptables).  I stand amazed.

Cheers,
-Jon