NAT port forwarding

Question

I have recently purchased a Cisco 871 router. In the GUI from the installed software, I have been able to configure which ports are forwarded to a specified IP address within my local area network.
This seems to output a configuration line like this:
ip nat inside source static tcp 192.168.1.123 1000 interface Dialer0 1000
However, I can only do this one port at a time. Is there a function or command that I can use to specify a range of ports? For example, I would like to forward tcp ports 1000-2300 to the IP address 192.168.1.123.
Any help would be appreciated.
(p.s: I think I posted in the wrong Topic previously)

Answer 1

Hi
I own a 2621xm which I have used for port forwarding with NAT overload. from what I can see your options are to forward a port onto the address of your NATed interface with the command:
ip nat inside source static (tcp/udp) your.inside.ip.address portnumber your.interface.ip.address externalportnumber
eg
ip nat inside source static tcp 192.168.1.43 22 194.41.66.2 8022
would allow me to reach 192.168.1.43 port 22 from outside using 8022 or whatever port you specify in the command.
alternatively you could change the interface address to one in the same network so that it is seen as a different devicewith a different ip that only has the forwarded port open.
the final way would be to forward the entire inside address to a new external ip address for example if you have a 192.168.0.0 /24 NATed to 194.41.66.0 /24 through an interface with an ip of 194.41.66.2 you could run the folowing command:
ip nat inside source static 192.168.1.43 194.41.66.43
allowing you to communicate with that host as if there was no NAT. from here you can use the access-list feature to close ports that you don't need.
Hope this helps!
Barry