Opening ports on Cisco 677 DSL router

[Guest_imported]

I have a small home network that uses a Cisco 677 router to connect to the internet. I am unable to play certain games online and use MSN Messagener type services. I am told the reason is that the router does not have the required ports open.

The external IP address is a static address xx.xxx.xxx.xx while the internal IP address is 10.0.0.3. How do I open ports in the router that will allow me to use these services? Please be as simple and complete as possible.

If I open these ports am I asking for trouble?

 

[Guest_imported]

I have the same problem, i open all the port of messenger but i cant send file, and i cant chat with camera. I only receive. If you fix the problem please tell me.

thx

 

[cgoodness]

Are you attempting to actually host these services, or just access them on some server. The reason I ask is that if you are hosting them, i.e. quake, etc. it's no different than hosting a web server. If you are just attempting to access these services elsewere, it may be (albeit unlikely) that your ISP blocks those ports outbound to save bandwidth.

I'm pretty sure that it sounds like that cisco device is doing some form of Network Address Translation (although i'd have to see the config to confirm that). Here are some quick Port Address Translation statments that might help.

Sorry if these are no help.

(POP3)
ip nat inside source static tcp 10.1.2.1 110 44.4.2.1 110 extendable
(SMTP)
ip nat inside source static tcp 10.1.2.1 25 44.4.2.2 25 extendable