## Block all in and open for certain ports

iptables -A FORWARD -o eth1 -p TCP --dport 6112 -j ACCEPT
iptables -A FORWARD -o eth1 -p TCP -j REJECT

## Block all out and open for certain ports

iptables -A FORWARD -i eth1 -o eth2 -p TCP --dport 6112 -j ACCEPT
iptables -A FORWARD -i eth1 -o eth2 -p TCP -j REJECT