I have a series of Ubuntu 10.04 servers and each one has ufw firewall enabled. I have allowed port 22 (for SSH) and 80 (if it's a webserver). My question is that I am trying to enable icmp echo response (ping reply).
ICMP functions differently than other protocols--I know it is below the IP level in a technical sense. You can just type
sudo ufw allow 22, but you cannot type
sudo ufw allow icmp