Set up on client side
To enable the keep alive option system-wide (root access required), you should edit the file /etc/ssh/ssh_config and add these options:
You can also set the settings for just your user, editing the file (or create it if it doesn’t exist) ~/.ssh/config , the options are exactly the same.
Set up on server side
You can make your OpenSSH server keep alive all connections with clients by adding the following to the file /etc/ssh/sshd_config:
With these settings will make the SSH client or server send a null packet to the other side every 300 seconds (5 minutes), and give up if it doesn’t receive any response after 3 tries, at which point the connection is likely to have been discarded anyway.