how to set the idle-timeout in linux SSH

[Alexander Apprich]

M E Fieu wrote:
>>from "man sshd_config"
>>
>>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.  This option applies to protocol version
>>2 only.
>>ClientAliveCountMax
>>    Sets the number of client alive messages (see
>>above) which may be
>>    sent without sshd receiving any messages back
>>from the client.
>>    If this threshold is reached while client alive
>>messages are being
>>    sent, sshd will disconnect the client,
>>terminating the session.
>>    It is important to note that the use of client
>>alive messages is very
>>    different from TCPKeepAlive (below).  The client
>>alive mes-
>>    sages are sent through the encrypted channel and
>>therefore will not
>>    be spoofable.  The TCP keepalive option enabled
>>by TCPKeepAlive
>>    is spoofable.  The client alive mechanism is
>>valuable when the client
>>    or server depend on knowing when a connection
>>has become
>>    inactive.
>>
>>    The default value is 3.  If ClientAliveInterval
>>(above) is set to 15,
>>    and ClientAliveCountMax is left at the default,
>>unresponsive
>>    ssh clients will be disconnected after
>>approximately 45 seconds.
>>
>>Set this in your sshd_config and restart opensshd
>>
>>Hth
> 
> 
> 
>>From the sshd_config that I have, there is no entry
> like ClientAliveInterval and ClientAliveCountMax in
> this file.  Should I create the entry in that file?
> Besides, if there is no such entries in that file,
> what is the default value then ?
> 

in /etc/ssh/sshd_config insert

ClientAliveInterval 600
ClientAliveCountMax 3

That will give you an timeout of 30 minutes (600 sec x 3)

Alex