The commands are of the form: --multiplay=in | out,Hz,destination address,destination port --callsign=a_unique_name Below are some examples of startup commands that demonstrate the use of the multiplayer facilities. For two players on a local network or across the internet: ---------------------------------------------------------- Player1: --multiplay=out,10,192.168.0.3,5500 --multiplay=in,10,192.168.0.2,5501 --callsign=player1 Player2: --multiplay=out,10,192.168.0.2,5501 --multiplay=in,10,192.168.0.3,5500 --callsign=player2 For multiple players on a local network: ---------------------------------------- Player1: --multiplay=out,10,255.255.255.255,5500 --multiplay=in,10,255.255.255.255,5500 --callsign=player1 Playern: --multiplay=out,10,255.255.255.255,5500 --multiplay=in,10,255.255.255.255,5500 --callsign=playern Note that the callsign is used to identify each player in a multiplayer game so the callsigns must be unique. The multiplayer code ignores packets that are sent back to itself, as would occur with broadcasting when the rx and tx ports are the same. Multiple players sending to a single player: -------------------------------------------- Player1: --multiplay=out,10,192.168.0.2,5500 --callsign=player1 Player2: --multiplay=out,10,192.168.0.2,5500 --callsign=player2 Player3: --multiplay=out,10,192.168.0.2,5500 --callsign=player3 Player4 (rx only): --multiplay=in,10,192.168.0.2,5500 --callsign=player4 This demonstrates that it is possible to have multiple instances of Flightgear that send to a single instance that displays all the traffic. This is the sort of implementation that we are considering for use as a tower visual simulator. For use with a server: ---------------------- Oliver Schroeder has created a server for multiplayer flightgear use. The server acts as a packet forwarding mechanism. When it receives a packet, it sends it to all other active players in the vicinity (the server is configured to use 100nm by default). Check out the server homepage for the current status. You can either download the server for some local use, or join the developers flying at the existing servers. As with flightgear, the server is free software, released under GPL. Pigeon has created a web page monitoring two such servers, showing the traffic in a Google map environment. See . Options needed to enable multiplayer game with a server: Player1: --multiplay=out,10,serveraddress,5002 --multiplay=in,10,myaddress,5002 --callsign=player1 Player2: --multiplay=out,10,serveraddress,5002 --multiplay=in,10,myaddress,5002 --callsign=player2 ... PlayerN: --multiplay=out,10,serveraddress,5002 --multiplay=in,10,myaddress,5002 --callsign=playerN Note that if every player using a particular server, such as one of those listed on the Pigeon's page, needs to have a unique callsign, not already in use on that server. If you are sitting behind a NAT'ting firewall, then you need to forward the incoming traffic on the firewall outer (visible to the internet) address arriving at the UDP port you use (5002 in the case above) over to your private LAN address. In this case, use your PRIVATE LAN address as . Example (if your private LAN address is 10.0.0.1, in order to play on pigeond.net): fgfs --multiplay=in,10,10.0.0.1,5002 --multiplay=out,10,pigeond.net,5002 --callsign=...UNIQUE callsign here... If you and the server are in the same address space (i.e., both have a public IP address or both are on the same private LAN), you hopefully don't need to mess with any firewalls. If you don't see other players playing on the same server in your flightgear, check that you have followed the above router configuration guidelines. Check that you don't have any LOCAL firewall running on your computer preventing the flightgear network traffic flow. Finally, use ethereal(1) or tethereal(1) to capture the UDP traffic on the port that you are using, and see if you observe both incoming and outgoing packets. It's a good idea to talk to the IRC channel #flightgear on irc.flightgear.org while flying on one of the public servers. Also, it makes sense for every user on the same server to use the same weather setup, e.g., the real weather METAR feed, selected by setting to true the real-world-weather-fetch and control-fdm-atmosphere properties. Further reading (a must if you have a problem): ----------------------------------------------- [1] The flightgear server homepage [2] The flightgear wiki multiplayer howto [3] If everything else fails, ask for help on the IRC channel #flightgear on irc.flightgear.org