GSEmulator is an (incomplete) implementation of the Gamespy QR2 (Query and Report 2) module which allows to expand and/or modify the information that is reported and querying a game server. It maintains a state of the game by receiving updates (via python) directly from the game.

Clients query the game server as usual but these UDP packets get intercepted and redirected to GSEmulator which then replies ( instead of the game).

In windows the intercepting part is done with GSDiverter.

In Linux, the interception can be done using iptables:

sudo iptables -t nat -A PREROUTING -p udp --dport <GAME_QUERY_PORT> -j REDIRECT --to-port <GSEMULATOR_PORT> ,where:

• GAME_QUERY_PORT is the port number used by the game to handle query requests
• GSEMULATOR_PORT is the port number binded to the emulator.

GSEmulator.exe <options>:
  Options:
  -ip <ip address>              Defines the IP where this emulater will listen from
  -port <port>        REQUIRED  Defines the Port where this emulater will listen from
  -bfip <ip address>            Defines the IP where the game is listening from
  -bfport <port>      REQUIRED  Defines the port where the game is listening from