Sometimes, when you are in a NAT’ed environment, ssh connection may be dropped when the gateway is busy.

OpenSSH has provided a solution against this.

The option is called “ClientAliveInterval”. With this setting in your sshd_config, sshd(8) would send a ping message through the encrypted channel periodically, thus prevent the early drop.

The default setting is 15, meaning the ping period is 15 seconds.

It seems that sshd_config(5) has provided more and more related options, which is quite interesting.