We need a router to translate a TCP port for a connection between an inside device and an outside server.
The outside server (188.8.131.52) will establish a connection to the inside device (10.0.0.10) on TCP port 123, but the inside device is listening on port 234. The router will need to forward inbound traffic destined for 10.0.0.10 port 123 to 10.0.0.10 port 234.
I have found very simple instructions for doing this here, but when I try this I get duplicate IP address errors and the router seems to take over the inside device's IP address. (A "show ip arp" will show the router's MAC address for the inside device.)
ip nat inside source static tcp 10.0.0.10 234 10.0.0.10 123
What could I be doing wrong? The instructions are from 2006. Has Cisco changed NAT since then?