airport's dhcp server is fubar and i can't turn it off

Discussion in 'Mac Basics and Help' started by janey, Feb 9, 2006.

  1. janey macrumors 603


    Dec 20, 2002
    sunny los angeles
    The setup: I have a DSL modem. That DSL modem goes to my Airport Extreme base station. Extreme base station is bridged with an Express base station with the former being the main one. I have miscellaneous things plugged into both - speakers, printers, whatever. For the sake of simplicity assume that there are two computers on the network - one is wireless (iBook on 10.4) and the other is a wired desktop (linux) that's connected to the Express base station.

    What I need: Both computers need a particular IP address for the purpose of port forwarding and things for bittorrent, ssh, apache, vnc, dns, et cetera. (I mean, by next week would be great...I do occasionally take a quick trip to the lab or pop open my laptop to grab homework from my desktop that i forgot to bring :eek: and things like that) The computers used to have nice IP addresses for short amounts of time but after a while they sometimes get assigned something different from the port mapping and it's truly annoying.

    Attempt 1: Assigned static IPs to both computers (yes, I filled out everything, not just the IP). Manually, DHCP with manual address, blah blah. Both are utterly useless for anything beyond the local network (network is unreachable, no route to host). That's despite resetting things multiple times and such. (or, was it wrong to do sudo ifconfig eth0 ..., ifup eth0...dhclient..whatever.. or what?)

    Attempt 2: Changed DHCP lease period from the Airport's default 4 hours to like 999 days, to see if machines could keep the same IP address for a long period of time. Although this sort of worked (okay, so I could get on IRC and stuff...), the Airport DHCP server refused to assign a mass of IP addresses (mostly ones that were convenient to me). i.e. I wanted the two base stations to have and, the desktop to have and the iBook to have No matter how many times the base stations were reset (reset reset to default values), it refused to assign particular IP addresses, and instead assigned ridiculous ones like which would change every time I changed the port mapping to map to the new IP addresses. Dug around a bit with nmap, checked out the MAC address that was given to me in some random OS X error dialog,...nothing had 192.168.1.x (2<x<255) and the MAC address was Does OS X regularly make up MAC addresses or what?

    Attempt 3: Tried to figure out a way to disable DHCP but not NAT on the base stations in an effort to use my own dhcp server (as in, configure dhcpd to give a predetermined IP address to specific MAC addresses, to say the least...much more flexible than what Airport seems to have..). Not entirely pleasant to have two DHCP servers on the same network :) It's possible to disable's possible to disable DHCP and NAT...but it's not possible to disable DHCP but leave NAT. (Or is this a bad idea? I'm not entirely too sure...should I just turn off both?)

    So, having thought about and attempted all three possible solutions I could come up with in all sorts of different ways (with only one base station, or with only the desktop, or only the laptop...), I googled around a bit.

    This is when I find out about this supposedly very useful Java Airport Configurator by Jonathan Sevy. I mean...there are actually people out there who were stuck in the same situation, and they used this tool, and it solved all their problems for them. [like and] But...It's not entirely useful in that the only site to get a copy of said configurator is...dead.
    Edit: wait...its not dead...that link is just bad I guess... new link:

    [But short of running dhcpd on my desktop and getting a copy of the airport configurator sometime soon] Without having to deal with the Airport configurator and an external DHCP server, is there a fix for problems encountered above, or something I haven't tried that works? Or some explanation as to why (or 5, or 100...) is assigned to a machine that seems to have a nonexistant MAC address? Or why Airport hates static IPs?

    Any help would be much appreciated :)
  2. mklos macrumors 68000


    Dec 4, 2002
    My house!
    This may not be what you're looking for and sound totally stupid, but have you tried to do a factory reset the AirPort(s) and then reload the Airport updates back into the AirPort(s)? Then try doing what you want to do. Maybe something is just screwed up and needs to be reset.
  3. janey thread starter macrumors 603


    Dec 20, 2002
    sunny los angeles
    In the beginning I was only restarting them, but yes, eventually I started to do like a total reset every time I tried something new, just to make sure it wasn't just a quirk from any sort of update or configuration.

    Then again, it's been like this for a long time now, across multiple updates, and it hasn't annoyed me to this end until now.

    And also, the Java config deal doesn't seem to be working, so I don't know. I'm thinking about just getting a more configurable wireless deal - maybe one that has what I'm looking for (MAC-based IP address assignment - not filtering, but assigning specific IP addresses to specific MAC addresses), or something that lets me turn off what I don't want.

    Someone on #macwarez on efnet told me to set up Airport to only assign one address using DHCP (to the computer running dhcpd), so by running two DHCP servers on the same network in that fashion would force clients to get a dhcp lease from the computer and not Airport, but I tried that and it doesn't seem to work quite the way I want it to (like the port mapping gets funky).

    Then again, the NAT-PMP option in Airport settings would be a nice to solve all my problems (well, if apps had support for this stuff..) - port mapping on the fly - but the only problem is that NAT-PMP's unique to 10.4, and there are non-10.4 based computers on the same network. Then again, NAT-PMP is Apple's alternative to the UPnP (in particular IGD) deal, which doesn't work on Airport (i dont think..).
  4. killmoms macrumors 68040


    Jun 23, 2003
    Washington, DC
    Um, maybe the Airport base stations can't do this, but on other wireless routers (or even regular wired home NAT routers), you can set the DHCP range of addresses to be a certain subset of the entire subnet, like, say, 100 - 254. Then anything below 100 you can assign manually and it'll behave just fine. So people connecting who don't need a static internal IP would get one automatically with no problem, and you could manually assign or .5 or something as static internal IPs for the machines that needed them.

    So yeah, haven't used an Apple AirPort base station before, but I'd imagine something like this is possible.
  5. prostuff1 macrumors 65816


    Jul 29, 2005
    Don't step into the kawoosh...
    I have a Linksys wireless router and what i have found is that on my home local network my computers are assigned two different IP address, but these are only local. Mine give me a and Each is specific to each mac.

    when i want to VNC to my desktop while i am away i have to find the external IP. The best place i have found to do this is either this website or use a widget like this one. The other thing that is possible is to try this site and set up a dynamic dns for the computer. that way the ip is the same all the time (at least that is what i have gathered from reading on the site). I am not quite sure how this works or how well it works because i did not bother to do this step cause i usually just check my external ip before i leave the house. I will probably do this step before i leave for college cause i am going to leave on of my computers at home.

    Not quite sure if that will help you at all but...

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