Oops, just iptabled myself off the planet...
Been there, done that a few years back...
If memory serves I added a comma where there shouldn't have been a comma in the iptables configuration file in RedHat, I then did "sudo /etc/init.d/iptables restart". Boom, I lose the connection.
The server was located in Singapore. I was in Iceland, two countries about as far away from eachother as they come. Luckily we had a guy there who was able to fix it while on the phone with us, so we were only down for a few minutes.
After that it became a policy to put an "at" event (basically a one-time cronjob) to roll back the iptables changes a couple of minutes after they were made, the "at " event would then be promptly removed from queue once we were certain the rule was applied and didn't kick us offline.