PunkBuster

PunkBuster is a third-party anti-cheat application developed by EvenBalance, Inc to combat cheating in online multiplayer games. Punkbuster and Evenbalance, Inc are not affiliated with the Valve Anti-Cheat (VAC) system, Valve Software or Steam. Please do not contact Steam Support regarding issues related to PunkBuster.

The following games currently available on Steam make use of the Punkbuster application for multiplayer games. Please follow the links below for support specific to the game you are attempting to play:

• Call of Duty
• Call of Duty: United Offensive
• Call of Duty 2
• Call of Duty 4: Modern Warfare
• Doom 3
• Enemy Territory: Quake Wars
• Prey
• Quake III Arena
• Quake III Team Arena
• Return to Castle Wolfenstein

Game Problem: Disconnected from a game server because of Punkbuster

During a multiplayer game, you may experience issues such as being disconnected from game servers for the following reasons:

• Punkbuster is out of date
• Punkbuster is not enabled. Please enable Punkbuster to join this server

If you suspect that Punkbuster is not up to date, please visit Evenbalance for a manual update application. Certain multiplayer servers may not require the most recent version of PunkBuster. This is why the game may have worked for a certain period of time until problems began to arise.

How To Enable PunkBuster

To enable Punkbuster, please launch the game you are attempting to play and look for the option in the game's multiplayer settings. To ensure that PunkBuster is enabled, please check the box where it says "enable".

Connection Issues

PunkBuster requires that your network allow traffic on the following UDP port: 27666. You must configure your network to allow UDP traffic on this port in order to use PunkBuster.

Certain routers have been known to cause connection issues with PunkBuster. Listed below are some of those models and the recommended firmware version to use in order to avoid these issues:

• Linksys - possible solution: Use firmware 1.44.2
• Motorola - possible solution: Update to latest firmware
• Netgear - possible solution: Disable SPI (statefull packet inspection)

Please make sure that you consult your router's instruction manual before updating the firmware. If you have trouble while performing a firmware update, please contact your router manufacturer for assistance.

Game Error: "Unknown Windows API Function [1311xx]"

This error is caused by having the Steam Community In-Game Overlay turned on and PunkBuster detects it as a cheat. In order to circumvent this issue and play your game, please disable the In-Game Overlay by following these steps:

1. Click the "Settings" button in Steam or click "File" -> "Settings" from Steam's main menu
2. Click the "In-Game" tab in the Steam settings
3. Uncheck the option "Enable Steam Community In-Game"
4. Click "Ok"