Iptables
List rules
iptables -SAdd rules
iptables -A {INPUT/OUTPUT} -d/s {dest/src} -p {tcp/udp} -m {tcp/udp} --dport/sport {PORT} -j {ACCEPT/DENY}iptables -Siptables -A {INPUT/OUTPUT} -d/s {dest/src} -p {tcp/udp} -m {tcp/udp} --dport/sport {PORT} -j {ACCEPT/DENY}