Redirect ports with IPtables

For whatever reason you may want to remap a high port to a low port. Here is how you can do it with IPtables. In this example we are going to remap 23420 to port 25 on IP address 192.168.1.1.

iptables -t nat -A PREROUTING -p tcp --dport 23420 -j DNAT --to 192.168.1.1:25