Port forwarding on Cisco 1800 series - Help

| Can someone help explain how I can forward ports, such as 80, from a | public DHCP address, to an Internal LAN address? | | Because my public IP changes often I'm not sure how I can NAT that to | an internal LAN ip such as 192.168.1.103 port 80. | | Currently my router is setup like so to NAT outside: | | ip nat inside source list 1 interface FastEthernet1 overload | | But not sure how I can take the DHCP assigned IP/port to an internal | IP.

ip nat inside source static tcp 192.168.1.103 80 interface FastEthernet1

Thanks for quick reply, but...seems extendable is seen as invalid input. Maybe IOS?

Thor(config)#ip nat inside source static tcp 192.168.1.103 80 int f1

Thor(config)#$de source static tcp 192.168.1.103 80 int f1 80 ext ? % Unrecognized command ip nat inside source static tcp 192.168.1.103 80 int f1 80 extendable =20 ^

Not sure what's up, but under initial config I was able to enter the line with extendable, however after finalizing my config that last arg was no longer available, so appear that something in my config is changing so that I can not use this line?

Would it be due to using DHCP or maybe my config to NAT outside for my LAN?

It's odd that it was available at first then as I was ready to enter the line after initial config that it was no longer available.

om

I'm beginning to think this syntax is not correct:

ip nat inside source static tcp 192.168.1.103 80 interface FastEthernet1

Any other suggestions ?

Thanks.

I think it should be "overload" instead of "extendable".

Nope...will not take any args after the port number. The help "?" shows as the last option in this case.

Is very odd, because seems should be such a simple thing to do.

And it does not work?

Nope...does not work. So will take the command without the last arg, but just does not work. I can enter the command with the extendable arg if I use the external IP address vs the interface, however that won't work because my external (public) IP is assigned via DHCP.

Seems so close, but so far:(

This works:

ip nat inside source static tcp 192.168.1.103 22 68.204.221.132 22 extendable

But obviously that won't do because the IP will change. Using DDNS to always get to my internal IP.

Ouch! I didn't notice that my DDNS was not working...

Turns out this does work:

ip nat inside source static tcp 192.168.1.103 22 interface Ethernet0

My DDNS name was not being updated for some reason and IP had changed.

Thanks for all the feedback!

...walks away red faced....

| > ip nat inside source static tcp 192.168.1.103 80 interface FastEthernet1 | > 80 extendable | | Thanks for quick reply, but...seems extendable is seen as invalid | input. Maybe IOS?

Try without the extendable command. It should work.

Thanks...you are correct...worked without extendable:)

I never use "extendable" I read the documentation, failed to understand it at all and have never looked back:-)

It is in a lot of Cisco examples and lots of people do seem to put it in their NAT statements but I kind of like to know what is going on.

I'll probably never use it either. I too tried to make sense of it, but just couldn't see why it is necessary. Seems fine without it:)