Stuff

#!/bin/sh

IPTABLES=/sbin/iptables
EXT_NIC=ath0
INT_NIC=eth0

# flush iptables rules
${IPTABLES} --flush
# flush the NAT table
${IPTABLES} --table nat --flush
# delete all extra chains
${IPTABLES} --delete-chain
# delete all extra chains from the NAT table
${IPTABLES} --table nat --delete-chain

# Masquerade packets out on the external interface
${IPTABLES} --table nat --append POSTROUTING --out-interface ${EXT_NIC} -j MASQUERADE
# accept and forward packages coming in on the internal interface
${IPTABLES} --append FORWARD --in-interface ${INT_NIC} -j ACCEPT

# Accept packets on external interface
${IPTABLES} --table nat --append PREROUTING --protocol tcp --in-interface ${EXT_NIC} -d 192.168.0.13 --dport 5050 -j DNAT --to 192.168.2.2:5050
${IPTABLES} --table nat --append PREROUTING --protocol tcp --in-interface ${EXT_NIC} -d 192.168.0.13 --dport 113 -j DNAT --to 192.168.2.2:113