Recently upgraded a server from Redhat 5.2 to Redhat 6.0.
The server is in front of the local firewall machine and
when telnetting from behind the firewall will be
disconnected from the server after a maximum of 30 minutes
of being idle. If accessed from an outside source telnet is
not disconnected even after hours of being idle, also a
Redhat 5.2 machine that has not been upgraded does not
disconnect the telnet sessions from behind the firewall.
are you using tcsh or bash as your shell?
we use bash as the default shell
This is almost certainly a problem in your firewall. For example, Linux
Firewalls disconnect idle TCP connections after certain period of time unless
keepalive messages are sent.
If the firewall in question is Linux, you might want to check out 'ipchains -M'.
Also, you could try to downgrade your 6.0 -system's telnet RPM to one from 5.2,
to see if you can isolate the problem.