FAQ

Why my IP address is not visible to other players?

If you have tried to act as a host of a game that is to be played on the Internet, and have delivered to other players your IP address as advised in the FAQ article How can I identify my IP address , but none of the other players see the session you have created, please note that the following situations are likely to cause problems:

The hosting player is behind a firewall.
Check if another player who is not using a firewall, or who uses a firewall system that can easily be modified, can act as a host.
For instructions for setting up a game with a firewall, please check the article How to configure a firewall.
The hosting player uses ICS (Internet connection sharing) and is not directly connected to the Internet (but rather uses a service of another computer on a local area network).
The IP address shown by Winipconfig.exe (or similar utility) is internal and cannot be used by other players to connect to your computer.
Check if another player with a true IP address (that can be used by other players) can act as a host.
The hosting player has a multihomed PC, meaning that he has more than one LAN adapter, both using TCP/IP protocol (or a LAN adapter and a modem, both using TCP/IP).
Please use WinIPcfg.exe (or IPConfig.exe), as advised the the article How can I identify my IP address , to assure that you have given the address of the correct adapter (and not the address you use for internal connections).
If the problems continue, check if another player who does not have a multihomed PC can act as a host.
Your ISP (Internet service provide) is translating your network address: With the growing number of users on the Internet, some ISPs (especially DSL providers) have begun to utilize network address translation (also called NAT) to dynamically allocate their limited number of IP addresses.
This is a similar situation than in ICS (Internet connection sharing), meaning that your IP address is not public and cannot be used by other players to connect to your computer.
Check if another player with a true IP address can act as a host.

Note: Even if one or more of the above conditions (excluding the firewall, which must be modified to allow traffic with certain ports) are true, you should still be able to join games hosted by someone else.