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 or firewalld services. asl-firewall replaces both the iptables and firewalld services. Enabling or starting these services will break your systems firewall and will likely prevent you from accessing the system.