Keeping SSH session alive over a restrictive proxy/firewall

[Taylor Jones]

First, here is my problem. I am connecting to a remote computer over SSH on port 443 using PuTTY. I had to use 443 to get around restrictive proxy/firewall rules, which worked great except for one thing: If I leave the terminal idle for more than about 4 or 5 minutes the proxy drops my connection. Luckily I always work within a screen session so I can pick up right where I left off when I reconnect, but this is still an annoying hassle. 

Any Ideas? The best solution I have found is to run 'top' when I'm not using the connection, but I don't always remember to do this. The silence notification feature of screen seemed promising (e.g. setup a recurring notification occuring every 3 minutes) but the notifications only occur one-time, not continuously.

Thanks for your help!

- Taylor