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Wireless Networking Hardware

Disabling Wireless Networks? 63

Posted by Cliff
from the ssid-jamming dept.
An Ominous Coward asks: "The University of Florida student chapter of ACM hosts a yearly programming competition for students throughout the state of Florida. It is based on the ACM International Collegiate Programming Contest, and for the past ten years has been very successful, currently drawing a crowd in the hundreds. However, this year was the first we had a problem with wireless networks. We doubt that cheating was the intention, as no one had SSID broadcasting turned off (as far as we know). Wireless networking gear is quite inexpensive now. And while we don't believe it affected the contest this year, we would like to take precautions for future contests. Is there any way to disable all wireless networking in an area about the size of a large lecture hall?"
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Disabling Wireless Networks?

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  • You should put little metal hats on all wireless antennas. That way the aliens can't get at those precious routers.

    Seriously, though, you may be able to setup a small microwave source(s) in the vicinity. Though it may not block all signals. It should effectively reduce the usefulness of anything within a reasonable area.
  • Why not use a university computer lab? Then you have total control. Or, take a look at everyone's laptop as it comes in. They can leave the card with you (like a coat check), or, if it has integrated wireless of some sort, let them use a spare desktop or laptop you've brought for the purpose.
    • by foidulus (743482) * on Friday June 04, 2004 @04:55PM (#9339328)
      Or, take a look at everyone's laptop as it comes in. They can leave the card with you (like a coat check), or, if it has integrated wireless of some sort, let them use a spare desktop or laptop you've brought for the purpose.
      That would be a lot of overhead. Are you going to check the specs of every system to ensure that it doesn't have a centrino processor(If someone were to cheat they would have no qualms about switching/removing stickers). I don't know how many powerbook/iBooks they get, but are you preparted to lift up the keyboard to look for an airport card on each one? Plus they could always sneak in wireless cards.
      It's much more practical to find a way to disable the networks instead of the cards.

    • Coatchecking ... that's basically unreasonable searching. Unless there is reasonable doubt defined by the college Judicial code or a warrant, no one should have access to your stuff. And how do you even determine what laptop has integrated wireless? Ask politely, and expect the subject to answer truthfully so you can take away their machine? What if someone removes the logos and stickers, how do you tell then?

      Also, there's an old saying ... if you outlaw guns, only outlaws will have guns. Or something
    • by jeffy124 (453342) on Friday June 04, 2004 @04:57PM (#9339369) Homepage Journal
      agreed. A setup where the host controls the show is best for this situation. I personally participated in the ACM's programming contests during their Fall '01 and '02 competitions, and can give info on the environment they use. (FWIW, we never got past the regional competition either year).

      Basically, the contest was staged in a typical university computer lab, and all the machines were using some special image created just for the contest and installed that morning. A log was created of all activity from the rooms being used, and checked later (I think the admin did this via a router or firewall). Any activity other than the network connection required for the submission software got your team DQ'd.
      • agreed. A setup where the host controls the show is best for this situation.

        The advantage of people using their own machines is they have their own environment, their own prefrences, and all the settings which they would like to use. If you're an emacs lover, what would you do if a contest stuck you with vi, or vice versa? What of all the small-time IDEs and editors which are adored by their users (both of them!)?

        • You're not constrained to a specific editor. You could use anything the system had on it. Emacs, vi, pico, some Notepad-like tool that was in the desktop (forget if it was gnome or kde), whatever. No special IDEs - just the regular gcc, g++, or IBM's Java SDK were provided and also used on the judging side (IBM was a contest sponsor).

          The only real problem regarding editors was for emacs users, especially those used to their own config setup. But - those are the breaks of participating in such a contest
  • Provide all you can eat frozen burritos and fill the room with microwaves
  • In the can (Score:5, Funny)

    by crstophr (529410) on Friday June 04, 2004 @04:41PM (#9339140) Homepage
    Make everyone work in a shielded metal, enclosed cubicle and change the name of the contest to:
    "Code in a Can"

    --Chris
    • Re:In the can (Score:3, Informative)

      by harrkev (623093)
      At my job, people who do clasified work do this. It is called a "vault." And the radio reception in there is terrible. No music :(
  • by ForestGrump (644805) on Friday June 04, 2004 @04:42PM (#9339155) Homepage Journal
    just run a microwave oven in the back, a few cordless phones, a few rouge APs
    hopefully that is enough noise to kill most networks...

    or just make it very clear: NO WIRELESS NETWORKS. Walk around with netstumbler and a directional antenna. After a few people get antennas pointed at them, the networks will stop.

    -Grump
    • or just make it very clear: NO WIRELESS NETWORKS. Walk around with netstumbler and a directional antenna. After a few people get antennas pointed at them, the networks will stop.

      I think that is a good idea. You could log all traffic, and the location within you lecture hall with 3 modified linksys 'G' wifi routers. Record the information, and afterwords ban the offenders.

      IMHO I am sure that if you though some people were cheating that you could demand their laptop/etc and get their wep key. You co

    • Don't use computers. Use a pen and pad. Good programming should be done before it's entered on a computer.

      I do like the idea of just saying No wireless networks. Monitor, if you catch them - humiliate them, then ban them for a couple years.
  • by ubiquitin (28396) * on Friday June 04, 2004 @04:42PM (#9339158) Homepage Journal
    ... use a high-signal white noise generator [rfdesign.com].
  • AirJack (Score:5, Interesting)

    by .@. (21735) on Friday June 04, 2004 @04:44PM (#9339184) Homepage
    Simple. You simply forge the MAC of the access point (or just use the broadcast MAC), and spew dissociate/deauthenticate frames. As long as you're transmitting, nobody in range of the transmission can associate with an access point.

    This was the basis for the AirJack tool.
  • If I recall (Score:4, Interesting)

    by Jahf (21968) on Friday June 04, 2004 @04:45PM (#9339209) Journal
    There was a project that would broadcast tons of fake SSIDs in an attempt to obscure the right one.

    Given that principle, would it be possible to create a box that intercepts and responds with junk to any 802.11 packet it encounters?

    Not sure, but I've given it thought myself when giving a class where everyone is sitting there checking email (when you give a 3-day bootcamp on a subject everyone starts to drift -if- there is a distraction ... I don't care if they want to check, but they can get up and do the checking in another room ... 1 distraction leads to 2 and on and on).

    You don't necessarily need to -block- 802.11 traffic if you can make the existing networks worthless by giving junk back to the 802.11 clients. Perhaps masquerading the MAC of any AP you find active would be enough?
    • I don't care if they want to check, but they can get up and do the checking in another room ... 1 distraction leads to 2 and on and on).

      One leads to another, then ten, then more,
      And no one buys anything from the store!
      So no one gets paid and they can't make more,
      The posse breaks up and that closes the door!
      DON'T COPY!! (DON'T COPY THAT FLOPPY)

      Click Here [ninjaculture.com] before you mod me down. It is the FUNNIEST video ever. Email me if you want a copy of it; I can dcc it on irc or something to you.

      Chris

  • by gmaestro (316742) <jason...guidry@@@gmail...com> on Friday June 04, 2004 @04:55PM (#9339337)
    What we really need to do is figure out how to disable wireless phones in an area about the size of a movie theatre or concert hall. Perhaps something slightly less lethal than a shotgun.
    • I see no problems with the low-tech "shotgun" approach.
    • > What we really need to do is figure out how to disable wireless phones in an
      > area about the size of a movie theatre or concert hall. Perhaps something
      > slightly less lethal than a shotgun.

      The lethality of a shotgun depends on what kind of ammo you use. For example,
      if you load your shotgun with rock salt, it's a lot less lethal than if you
      use buck shot.
    • What we really need to do is figure out how to disable wireless phones in an area about the size of a movie theatre or concert hall.

      Actually, that isn't that hard, you just have to plan for it in the consruction. Before attaching drywall to the studs, put a layer of this mesh [twpinc.com] on the studs. That will block pretty much all RF based devices from reaching their towers.

    • I've seen a few cell phone jammers already. Check them out here [globalgadgetuk.com]. Says it can block them up to 15 meters (approximately 49 feet).

      Might be enough to stop people in theatres if you're lucky. Although we all know that shotguns would really be more effective...


      -Ares
  • by samgrover (102843) on Friday June 04, 2004 @04:58PM (#9339379) Homepage
    There are several 802.11 denial of service attacks explained in this paper [ucsd.edu]
  • by Cecil (37810) on Friday June 04, 2004 @05:06PM (#9339477) Homepage
    It's simple. Someone at OSConf in Toronto this year had no trouble taking out the entire WLAN with a laptop broadcasting in Ad-hoc mode on the same channel, same SSID.

    Idiot. *mutter*
  • by Blaze74 (523522) on Friday June 04, 2004 @05:20PM (#9339648)
    Most of the other posters here have mentioned ways to flood the network with bssids, etc. Chances are this will not work since the bssid's will be chosen by the cheaters. You will probably have more luck running kismet or some other sniffing tool to monitor the wireless network. Then you can see if anyone tries to use the wireless network.
  • by pr0c (604875) on Friday June 04, 2004 @05:32PM (#9339798)
    Ask my neighbor, the bastard seams to always screw up my router but thats alright, I'm within range of his router with a "Linksys" SSID with no encryption and no MAC filters that has a 3 meg cable connection.. I just borrow that =P I throttle my connection at 2.9, no need to be a dick about it.
  • TV kills the net (Score:1, Interesting)

    by Anonymous Coward
    Wireless AV transmitters [goldenshop.com.hk] kill WLAN. Uncompressed analog TV signals eat bandwidth like no tomorrow and these gadgets use the same ISM band as WLANs.
  • Did you try to implement this 802.11 WiFi Denial of Service Exploit Discovered [slashdot.org] Not So Long Time Ago?

    As far as I understand, this would block all 802.11x communication in the area.
  • by Anonymous Coward
    People could always hook up their palms or notebooks via bluetooth to their phone's data connection. If you're only checking for Wi-Fi signals, you won't catch cell phone cheaters.
  • Bigass transmitter (Score:2, Insightful)

    by billcopc (196330)
    Just get a humongous 2.4ghz transmitter to squash all the rogues on all channels.

    Or hire a bunch of evil nazi unabrow dykes to slap cheaters silly.

  • Just seal everyone inside of a Faraday cage at the start of each contest.

  • EMP's (Score:4, Funny)

    by Jorkapp (684095) <[moc.liamtoh] [ta] [ppakroj]> on Saturday June 05, 2004 @02:37PM (#9345258) Homepage
    A good solid EMP should disable all wireless networks in the vicinity*

    *as well as all computers, electronic gadgets, and vehicles built before 1980's

    The trouble is generating one. You can use either:

    - Very large capacitors, or...

    - A nuclear device **

    **With a nuclear device, you will not only disable all wireless networks, electronics, and vehicles built before the 1980's, but all humans, buildings, and organic matter for a very wide radius. No FCC complaints, but alot of DoD complaints will result.
    • by Wog (58146)
      Wouldn't a large EMP disable cars built *after* 1980, but not the ones before? Gizmos and all...
  • a very big magnetron should do the job adeuqately.
  • Bring a few wireless phones in the 2.4 ghtz range, they should create enough line noise to kill any connection.
  • I just read the latest issue of mobile pc magazine (no I am not affiliated with them in any way) - they had an article about signal jammers, which are getting much more affordable to own. They are effective in blocking a range of signals - including cell-phone, wifi etc. depending on type of jammers you get. You probably don't need to own it but just rent it - so it may be really affordable.

    Osho
  • Use a VPN who's concentrator forces the client to send a disabled bit for all other interfaces on the box. Cisco's VPN software can do this and you can modify it so that it also sends other flags such as a version or key that the end user probably wont be able to discover in time to duplicate with other compatiable VPN software. This would prevent you from using the wireless interfaces on a box.

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