On some *nix OS I have found security policies that forcibly disconnect terminal sessions believed to be idle. In which case keep-alives don't offer any help. One way to fool the policy is to leave the terminal with a blank "read" request.
prompt$ jobs
<stuff running in background (or not, just camping)>
prompt$ read
<terminal (and policy) thinks we are waiting for user input and dare not end our session>
When you return just hit enter, and you get your prompt back.
This is also a great way to keep "screen" sessions from being killed based on policy idle timeouts.
Of course your situation may be very different. Hope this helps, If not don't blame a guy for trying to help.