Can ddwrt change port number when forwarding?

Question

I use RDP all the time at work to remote to my home pc. Trouble is that port 3389 is blocked by our company firewall so I tweaked the RDP service at home to listen on the telnet port (23). My old router (3 years ago) used to be able to change the port number when forwarding (e.g. from 23 to 3389) so I didn't have to change the RDP listening port, but my newish Netgear doesn't have this option.

I'm looking at changing my router to a ddwrt based one (Buffalo WBMR-HP-G300H-EU) but I wondered whether ddwrt has the option to change the port when forwarding (this might have a specific name but I'm not sure what it is!). If not would another gigabit router offer this?

Answer 1

It is sometimes called Port Address Translation (PAT) or Network and Port Translation (NAPT)

It isn't mentioned in DD-WRT documentation for Port Forwarding

However it does discuss "Port Mapping"

Example: To map port 81 to internal port 80 on 192.168.1.2 issue the command

iptables -t nat -I PREROUTING -p tcp --dport 81 -j DNAT --to 192.168.1.2:80
iptables -I FORWARD -p tcp -d 192.168.1.2 --dport 80 -j ACCEPT

The down side with this is that it's not as obvious as the other methods but you can use a program called Firewall Builder to make this simpler. This setting will also disappear on router reboot if you don't place these commands inside of a Startup Script.