Add automatically open tunnel when open the session instead of startup

Hi, I need to enter the password twice to open the tunnel and the session respectively. Could you please add a option that automatically open tunnel when I open the session instead of starup, and only need enter the password once, just like OpenSSH. Thanks!

The issue names no files or tests; start by locating the session-opening and tunnel-startup entry points, then compare the requested flow with OpenSSH behavior. Done means an option opens the tunnel when the session starts and avoids requiring the password twice.

Written by the indexing model from the issue text.