Sounds like you need autossh. This will monitor an ssh tunnel and restart it as needed. 

http://www.debianadmin.com/autossh-automatically-restart-ssh-sessions-and-tunnels.html

Autossh example

autossh -M 5122 -N -R 5022:localhost:22 rex

Explanation:

Forward port 5022 on rex (the remote machine) to port 22 on localhost (the local machine).

Use port 5122 and 5123 will be used for connection monitoring.

（接上一条）解决ssh隧道断开自动重连的问题