Hi Friends,

My box has RHEL 5.7, my problem is the ssh terminal gets disconnected after 1 hour.
the sshd_config file have the below lines commented



#LoginGraceTime 2m


#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding no
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10
#PermitTunnel no
#ChrootDirectory none

and when try " echo $TMOUT " i get an null output

and i was not able to find the TMOUT option in /etc/profile, ~.bash_profile or ~.bashrc and still i get logged out exactly after 1 hour.

hope someone will have suggestions

These parameter are used for ssh connection timeout in /etc/sshd_config:
So remove the comment to TCPKeepAlive yes and set high values for ClientAliveInterval and ClientAliveCountMax (removing comments to relative lines too).

1 members found this post helpful.

I thought if ClientAliveInterval was set to the default of zero then these messages are not sent and no timeout and disconnect of idle ssh sessions is configured. So I'm not sure this is the issue in this case.

Did the changes suggested solve your issue?

Is the ssh client connecting directly or are there any firewalls in-between?

I know you mention this is affecting ssh clients, but do console sessions also get logged out after an hour?

Have you checked if there is any timeout set on your ssh client?
(There is a ServerAliveInterval for ssh_config, which you might want to review)

Is this the only RHEL host with this issue?

Have you tested from a different ssh client?

For ensuring an ssh connection remains in place you could look at something like autossh:

http://noone.org/blog/English/Comput...0Screen.futile

Hope this helps.

According to the sshd_config manpage ClientAliveInterval "Sets a timeout interval in seconds after which if no data has been received from the client, sshd will send a message through the encrypted channel to request a response from the client. The default is 0, indicating that these messages will not be sent to the client."
So if you set ClientAliveInterval to 0 NO request message will be sent.

Hi Bros thanks ,
I set it as given below - for 2 hrs

TCPKeepAlive yes
ClientAliveInterval 7200
ClientAliveCountMax 3

still no luck, it just logged out exactly after one hour.

ssh is connecting through firewall - which has set rule for 2hrs, so not related to network
even i tested from other clients - no luck
direct console am not getting logged out.
couldn't find any options to set in ssh clinets.
i tried adding " export TMOUT=0 " - still same

Try this:
In this way every 30 seconds when in idle the server will sent a request. It'll continue doing so for 3000 times.
30 secs x 3000 = 90000 secs = 250 mins = 4.166 hrs
If you use a too high value in ClientAliveInterval the request can be sent too late and it's possible that is the client closing connections (not the server).
You can even configure the ssh client (ssh_config) setting ServerAliveInterval on the clint e.g. to 60.

Use AutoSSH instead?

That's exactly my point, the OP listed his sshd_config and this was not set, so it must be at the default of 0, which means this should not be in effect.

I know you've mentioned the firewall config, but were these other clients also the other side of the firewall?

Is this the only server this issue is occurring on?

What ssh client are you using?

On the RHEL system console you could try:

If neither of these disconnect after an hour then I don't think it is related to any config on your server - it is then most likely either your ssh client config or something like a firewall.

Hope this helps.

Slackyman...thanks a lot..that did the trick, now its fine, changed my settings in the "sshd_config" file as you said

TCPKeepAlive yes
ClientAliveInterval 30
ClientAliveCountMax 3000

this 4 hours is okey for me, i can extend it as required in future .
i am using ssh client from windows machine...and i found the sshd_config file but everything is commented in it
and tried changing the time but didn't work.but changing in server sshd_config it's working....thanks a lot

i checked other servers too with the default settings, i think it's the same in all servers with various versions.

unSpawn :thanks..came to know about new sol.
maccas17 :let me check the one you mentioned with other servers, will update you.

I'm a bit confused where the original sshd_config values in your first post came from?
If ClientAliveInterval was indeed set to 0 then I don't see how this was causing the original disconnect issue.
Through setting them you have now enabled idle setting disconnect as per the ~4 hours Slackyman illustrated.

I already suggested AutoSSH in my earlier post

I would be very interested to hear if you find out anything further when testing this out.
Glad you've got a solution at any rate