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WAN DHCP failure (Tomato 1.07)

Discussion in 'Tomato Firmware' started by tompom, Jul 30, 2007.

  1. tompom

    tompom LI Guru Member

    I am having a strange problem. Just updated to Tomato 1.07 from DD-WRT v23 (had some problems with wireless). Things almost went wrong, I thought I bricked my router; couldn't reach it. Then I plugged the cable into the WAN (internet) port and it suddenly worked.... anyways:

    I cannot get the router to get an IP through DHCP from my cable modem. DD-WRT worked flawlessly, if I plug the cable into my PC it works, just not on my linksys.

    The logs keep saying:
    Jan 1 01:16:24 unknown local0.info udhcpc[354]: Entering released state
    Jan 1 01:16:44 unknown local0.info udhcpc[354]: Performing a DHCP renew
    Jan 1 01:16:44 unknown local0.debug udhcpc[354]: Sending discover...

    and this 'sending discover' keeps repeating and repeating and I don't get an IP. Weirdly on port1 the internal (LAN) DHCP wouldn't work, but that works all of a sudden. However I cannot get the internet to work.

    You guys have some idea?
  2. ifican

    ifican Network Guru Member

    reboot the modem then try.
  3. mstombs

    mstombs Network Guru Member

    Try ticking the box "Reduce Packet size" on the Advanced DHCP/DNS screen. I'm sure I've seen this in the FAQ...
  4. tompom

    tompom LI Guru Member

    I also did that (Reduce Packet size) but to no avail. I saw something strange in the logs just now though...

    The IP is my external IP and the MAC is the MAC of the PC I just connected to the router...why is it trying to do this?
  5. mstombs

    mstombs Network Guru Member

    OK now I see the problem. dnsmasq is the DHCP server for the LAN side of the router connected to br0. Your PC has the WAN IP from when it was connected to the cable modem directly, and it is trying to renew it from the router. You need to release the IP lease from your PC and then renew to get a local IP address served by the router.

    The router uses udhcpc as the DHCP client on the WAN side.

    It is possible your cable modem will only talk to the registered PC MAC address, try power cycling the modem, if that doesn't work, try "cloning" the PC MAC address onto the router.
  6. tompom

    tompom LI Guru Member

    Ah I see, that's why I don't see this in the logs anymore, I stopped switching cables and use my neighbor's internet to have a connection while I play with this.

    I've tried everything though from rebooting the PC, laptop, cable-modem, router, etc. nothing helped. There is no MAC-filter in the cable modem... really annoying. Is there anything I can do to diagnose this problem from an SSH connection to the router perhaps?
  7. ifican

    ifican Network Guru Member

    There generally isnt a mac filter in the cable modem persay, its on the isp end. They usually hold on the the original lease that your cable modem gets, usually by rebooting your cable modem you clear the isp table and it will respond to the query from the router vice the original query from your pc.
  8. tompom

    tompom LI Guru Member

    This is the full log after a boot:

    Let me see what happens if I unplug the cable-modem and turn it on a minute later :)
  9. tompom

    tompom LI Guru Member

    OMG ifican YOU ARE THE BEST :D. It works, it works! I am so happy :D. Perhaps this is some general knowledge but I think it should be put up somewhere because not knowing this cost me the whole afternoon even though I've installed custom firmware (dd-wrt, openwrt) at least a dozen times before.

    Big thanks to ifican, and I think to the author of Tomato, Jonathan when I'm done evaluating this firmware and am satisfied with it :bounce:
  10. ifican

    ifican Network Guru Member

    Im not the best you just didnt mention trying it, theres plenty of folks here that know that and would have mentioned it. Glad all is working, just remember that in the future so you can spread the knowledge as well.

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