Dying connection

[vp@example.com (Viktor Pavlenko)]

Hi,

I have to connect to a remote machine through the firewall.
Either it is a firewall option that I've no access to, or 
something else but my rlogin session dies after 30 min or so
if left idle.

The question is: how I can make rlogin/telnet to keep the
connection alive? Probably it can be done by sending a
packet once a while. I couldn't find anything relevant in
the man page.

Thanks in advance.

Viktor