A script I wrote a few years ago to keep myself from being locked out of remote
machines as I was tinkering with their firewall.

Example usage:

    $ cat # Your firewall script

    # Backup the current rules -B

    # Install new rules
    iptables -F
    iptables -I INPUT -i eth0 -j REJRECT
    ... and so on ...

    # Run firewatch in check mode, which will restore the old rules
    # if 'enter' is not pressed within 10 seconds. -C