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Hp-ux remote telnet session disconnected

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Andrea Rossi
Frequent Advisor

Hp-ux remote telnet session disconnected

Hi all

after downgrading wan connection I experience frequent disconnections in remote telnet unused session.
Hpux is 11, Terminal emulator is reflection.
No errors on firewall.
No messages on syslog.
I suspect that telnet keepalive packets are loss; can I disable them?
Is there a way log the disconnections on Hpux?

Michael Steele_2
Honored Contributor

Re: Hp-ux remote telnet session disconnected


a) Please verify that you have no error messages.

b) Are you using 'user' authentication like Kerboros?

Support Fatherhood - Stop Family Law
Honored Contributor

Re: Hp-ux remote telnet session disconnected

After the client indicates the session has been disconnected, connect again and see if the shell process of the old session has died or not.

(e.g. run "ps -fu ". If you see processes on multiple TTYs, use the "tty" command to identify your current TTY, then use "kill -HUP " to clean up the old sessions.)

If the process was still there, it means that as far as the server knows, the session has *not* been disconnected. This situation may be caused by a firewall purging its memory of inactive connections: a firewall will typically not pass through packets that belong to connections it isn't tracking (= has already purged). In the firewall's perspective, purging the memory of a connection that has become inactive is not necessarily an error.

This situation is caused by setting the firewall's no-traffic timeout to a shorter value than the keepalive value used by telnet. In effect, the firewall is too hasty in assuming that the connection is no longer used.

Disabling the keepalives won't help, and may actually make the problem worse, as the telnet connections have even less traffic than before. That would make the firewall even more likely to cull inactive telnet connections.

The fix would be to adjust either telnet's keepalive interval or the firewall's no-traffic timeout so that the keepalive interval becomes shorter than the no-traffic timout.

Andrea Rossi
Frequent Advisor

Re: Hp-ux remote telnet session disconnected

KeepAlive default on HPUX is 1 min.
Connection Timeout on firewall is 1h.