lifekeeper is a completely trivial program that prints an ASCII NUL character every 30 seconds. This has no effect visually, but if someone is watching the connection for activity it will see some. People using remote connections through firewalls might find it useful, as often masquerading firewalls are configured so to shut down connections that appear not to be active for some time.
There is a tar file contaning the source and man page and ready-to-use RPMs.
The suggested way of using lifekeeper is to start it as a background job in a configuration file read by your shell (e.g., $HOME/.bash_profile). lifekeeper exits when its parent does, so you do not need to kill it explicitly.
For instance, if you use the bash you should add the following lines to $HOME/.bash_profile:
# Is this an interactive shell? if [ "$PS1" ]; then lifekeeper & fi
If you want to be more careful, you should also check whether lifekeeper is installed at all, and whether you are connected via a local ssh (or other remote login protocol):
which lifekeeper &>/dev/null RC=$? if [[ "$PS1" \ && "$SSH_CLIENT" \ && $SSH_CLIENT != 127.0.0.1* \ && "$RC" = "0" ]]; then lifekeeper & fi