Cisco 877, 12.4(24)T. Single public IP, NAT to 192.168.1.x
I’m running a mailserver insider the LAN, and I connect to it from my laptop to send emails when inside and also when outside. When I’m travelling I sometimes encounter ISPs who are blocking port 25 to anything but their own mailserver, so I need to connect to a different port in order to send to my ow mailserver.
Ideally, what I want is for inbound traffic on port 25 to be forwarded to my mailserver, as normal. BUT I also want traffic on port 12345 to be forwarded to port 25 on the mailserver.