dhcp not working?

Discussion in 'DD-WRT Firmware' started by tracer, Jul 8, 2005.

  1. tracer

    tracer Network Guru Member

    i just loaded the prefinal5 but got a big problem..
    the dhcp ( lan side ) wont work..
    it just sits there "acquireing network adress" and fails.. dhcp = enabled but just doesnt do anything..

    is this a bug in prefinal5 ? or what else?
    so far dd-wrt seems great but i had to flash back to stock firmware because of dhcp not working..

    any help is appreciated :)
  2. MBChris

    MBChris Network Guru Member

    same issue here DHCP isn't working .... could be some "old" nvram Values ?
  3. tracer

    tracer Network Guru Member

    anybody else got the problem or know a solution?
  4. SteelersFANinMA

    SteelersFANinMA Network Guru Member

    Hi, I don't use DD-WRT, but have an idea. Since you say that you flashed back to the stock firmware and don't mention any issues there I doubt this is the problem, but you could check. Make sure that the DHCP service is started in windows. I know that once I get a new firmware up and going with static DNS, I stop the service to free up RAM and CPU. One time I forgot that I disabled DHCP and after flashing a new firmware, couldn't acquire an address. Once, you get connected and apply static DNS you can then stop the DHCP service so that only the router and not Windows will handle DHCP. In XP Home, you can find a list of services by typing: services.msc in the run box. 8) Good Luck!
  5. tracer

    tracer Network Guru Member

    nice idea .. only i never stopped the service and it was running.. it just couldnt get an adress from the router :) so i guess it must be a firmware issue
  6. DevilStick

    DevilStick Network Guru Member

    I have dhcp problems, too since flashing pre5, but with another strange effect.

    I have a WDS bridge. Since the router attached to the dsl modem is not physically accessable by me, it still has pre4 with dhcp enabled.

    While the router on my site had pre4, attached clients (wired or wireless) got a dhcp address via WDS bridge.
    After flashing it to pre5, I neither get a dhcp address assigned via LAN nor wireless.

    That is pretty strange.

    WRT54G (pre4) DHCP enabled ---))) WDS (((--- WRT54GS (pre4) --- DHCP-Client (works)


    WRT54G (pre4) DHCP enabled ---))) WDS (((--- WRT54GS (pre5) --- DHCP-Client (does not work any more)

    I installed tcpdump on the pre5 WRT and I see dhcp requests, but no answers. Does pre5 block dhcp for any reason?
  7. XCOM7

    XCOM7 Network Guru Member

    I had the same problem as you guys starting since the first prefinal5 than I found out that it was the old values messing every thing up...

    mtd nvram erase

    That did the trick now dhcp is working again :)
  8. DevilStick

    DevilStick Network Guru Member

    I tried nvram erase, but when I made nvram show, there were no changes. I even rebooted, but still old values.

    I typed:

    nvram erase
    nvram show

    Excact in this order. Since soft reboots cause a boot loop, I unplugged power and replugged it after a minute.
  9. XCOM7

    XCOM7 Network Guru Member


    mtd nvram erase
  10. DevilStick

    DevilStick Network Guru Member

    I see mtd is a command, I thought it's an abbrev. like IMHO :wink:

    Ok, will try it later, since not at home. hope this fixes my probs.

    I had pre4 running, printed every page as PDF, reset to firmware defaults, uploaded pre5-sneak, rebooted, reset to firmware defaults and configured it like before with the help of my PDF documentation.

    I'll try your nvram command. Can I use a saved pre5-sneak config to restore configuration? Since no version chance, this should be possible or is it advisable to restore config manually.

    Last task takes longer and will force my prim. WRT to reboot till config restored, since I have WDS watchdog activated on it with 120secs.
  11. XCOM7

    XCOM7 Network Guru Member

    Stay away from the final is to buggy use prefinal5 stable
  12. joebloggs

    joebloggs Network Guru Member

    What's your recommendation for reseting all the configurations and erasing the nvram values? I want to have a router that is fresh and cleared of previous settings.... i.e. like brand new.
  13. DevilStick

    DevilStick Network Guru Member


    Thanx for your hint. The correct syntax was mtd erase nvram and cleared my nvram.

    I played a bit around with Satori and Freeman (the static dhcp GUI is pretty cool. Should be adapted for DD-WRT) but since the RW filesystem did not work, there was no ipkg support and every config change forced router or gui to reboot, I switch back to pre5 from DD-WRT download area.

    Now, with cleared nvram, DHCP works again and the Internet Access page is displayed correctly. Seems as your solution did work.

    I only had to correct one nvram entry manually. Even with enabled jffs2-support under Administration/Management, I got no writeable jffs2.

    So I looked up the jffs2.startup-script and saw that sys_enable_jffs2=1 was missing which was queried by startup script. I added it, rebooted and now everything seems to work as expected.

    Soft reboot works again and there are no zombies any more. Only wireless hangs sometimes after changing values via GUI. The wl eth1 up command hangs and I have to reboot to get wlan again.

    Is this a known problem?
  14. tracer

    tracer Network Guru Member

    i'll load the prefinal5 again later on today.. and try the mtd nvram erase thingie :)

    who knows this thing may even work :p
  15. XCOM7

    XCOM7 Network Guru Member

    sorry about that...
    Thats what happen when you work grave yard shift and do not get enough sleep! :p

    I am glad dhcp is working again.
  16. tracer

    tracer Network Guru Member

    the mtd erase nvram did the trick here also ^^

    now i hope the large file transfer problem doesnt show up :)
    so far so good..

    but got another question..

    what is port triggering??
    dont see the difference with port forwarding..
  17. DevilStick

    DevilStick Network Guru Member

    Hmm, but after erasing nvram and setting up your system, you should not load old config backups. :? Now I have to restart whole procedure.

    Hey tracer. Now I know that I am not the only one that does no see any difference between forward and trigger. 8)

    Is it possible that triggering only opens a forwarded port when the port is in the given range? E.g. you use IRC and the packet has 6665-6668 as source, then you open port 113 for ident? Other packets addressed to port 113 will be discarded when not in trigger range?
  18. tracer

    tracer Network Guru Member

    google was my friend an i found something :)

    it seems you can let a something such as the ident be triggerd by a lan client.. thisway you dont need static dhcp or static ip's to create a port forwarding entry.. but simply.;when a client ( any client ) on the network triggers this entry ( the port in the entry to be exact ) it will temporarly use this forward

    its a weird thing this port triggering.. i'm not gonna use it .. not that great either.. 2 pc's at the same time..same trigger = a fight for who gets it.. so .. not that nice :)
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