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What's causing this bizarre UDP problem?

Discussion in 'Tomato Firmware' started by Christopher, Jun 22, 2010.

  1. Christopher

    Christopher Guest

    Using 1.27 on a WRT54GL with a Thomson TG585v7 running purely as an ethernet modem in bridge mode passing WAN traffic directly through. The WRT54GL has the public WAN address defined in its config and I can access it directly from the web via SSH/telnet/webui etc.

    Everything seems to work fine - except ONE game. QoS works beautifully, all static port forwards run great and uPnP works perfectly. Torrent traffic doesn't kill the device - I've made some minor tweaks to the TCP and UDP timeouts, mostly to stop my SIP devices failing to register (the known Tomato retry bug) but there's nothing drastic. The Tomato router acts as the LAN's default gateway, DHCP and DNS server. I'm on BE Broadband in the UK - there's no port filtering, traffic shaping or anything which might affect the connection.

    The one problem I am seeing is this: when I play Race Driver GRID online, the multiplayer mode uses uPnP to establish port forwards to connect with other players in a game. My housemate has an XBox 360 which functions in an identical manner, and this has always worked flawlessly both with DD-WRT and now, Tomato running on the router.

    However, whenever I join a multiplayer game over the Internet, at the same time in every game I get kicked out of the race - the infamous GRID 'kick bug'. (it's ten seconds after the start of the race). Unfortunately the game is going to receive no further updates so there's no prospect of Codemasters resolving this bug.

    Frustratingly, my friends all have no problems whatsoever playing across a variety of connections, OSes and so forth. I've even installed Windows 7 with nothing else except for system drivers and a copy of Race Driver GRID (to check for conflicting software or antivirus/firewall etc) and the problem is still there. I even reinstalled the entire game from scratch several times.

    I've not discounted that there is some odd conflict on my PC, but whilst I was trying to resolve the problem last night I noticed something very strange indeed. Viewing the Highest QoS statistics, I saw these connections, established by Race Driver GRID during a multiplayer session:

    UDP	3074 (	3074	Highest
    UDP	3074	host98.190-138-8.telecom.net.ar (	29724	Highest
    UDP	3074 (	3074	Highest
    UDP	3074	d72-39-199-49.home1.cgocable.net (	3074	Highest
    UDP	3074	host176.190-224-120.telecom.net.ar (	10035	Highest
    UDP	3074 (	3074	Highest
    UDP	3074	cpc1-ware3-0-0-cust328.lutn.cable.ntl.com (	3074	Highest
    UDP	3074	187-35-191-122.dsl.telesp.net.br (	3074	Highest
    UDP	3074 (	3074	Highest
    UDP	3074	modemcable015.44-21-96.mc.videotron.ca (	3074	Highest
    UDP	3074 (	3074	Highest
    UDP	3074	customer-200-81-202-194.millicom.com.ar (	3074	Highest
    UDP	3074 (	3074	Highest
    UDP	3074	201-41-205-9.jvece702.dsl.brasiltelecom.net.br (	3074	Highest
    TCP	16141 (	3074	Highest
    UDP	3074 (	3074	Highest
    UDP	3074 (	3074	Highest
    UDP	3074 (	3074	Highest
    UDP	1106 (	3074	Highest
    UDP	3074	195-241-125-234.ip.telfort.nl (	21422	Highest
    UDP	3074 (	11888	Highest
    UDP	3074 (	10043	Highest
    UDP	3074	27.85-86-83.dynamic.clientes.euskaltel.es (	3074	Highest
    UDP	3074 (	14652	Highest
    TCP	8832 (	27017	Highest
    TCP	8858	by2msg3010707.phx.gbl (	1863	Highest
    TCP	12184	www-11-02-ash2.facebook.com (	80	Highest

    You can see a couple of TCP connections (one is MSN Messenger, another is Facebook etc). All the UDP connections are GRID, which uses port 3074 for communication just as XBox Live games do. What particularly caught my eye was that in the list, there are some unroutable remote IPs - my LAN runs on, with NO other subnets, VLANs etc.

    I can see connections from,, They're clearly connections from other players in the multiplayer but they're all unrouteable, so I'm mystified as to why they're appearing in the connections list. Has anybody ever come across a problem like this, or might be able to help explain why it seems that my computer's trying to route to LAN IPs? (surely there can't be a regular situation where someone else's NAT would rewrite the internal IP to their connection's WAN IP?)


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