To configure the timeout for SSH sessions, let’s see where the SSH server configuration file is located:
sudo find / -name sshd_config
Open it in any text editor, for example nano:
sudo nano /etc/ssh/sshd_config
And we specify the timeout interval in seconds, for example 300 (this is 5 minutes), through which sshd requests a response from the client, the default value is 0, that is, requests are not sent to the client.
To terminate inactive connections, specify ClientAliveCountMax, which specifies the number of ClientAliveInterval without an answer, through which the connection will be terminated (the default value is 3):
That is, 300 seconds * 36 = 10800 seconds = 180 minutes = 3 hours.
Restart the ssh server to apply the changes:
sudo /etc/init.d/ssh restart
The method specified above terminates inactive connections and will not terminate active idle connections, so you can also specify the session timeout in the /etc/bash.bashrc file.
Let’s open it:
And add to the very end:
TMOUT=10800 readonly TMOUT export TMOUT
In this case, after the specified time, idle SSH and local sessions will be terminated.
You can see the number of active sessions in their idle time (IDLE):