If you need to reset the network firewall on your system to the defaults, run these commands as root:
service asl-firewall stop
rm -f /etc/asl/firewall/asl_stop.fw
service asl-firewall start
Note: Do not enable or use the iptables service. asl-firewall replaces the iptables service. Enabling or starting the iptables service will break your systems firewall and will likely prevent you from accessing the system.