Re: conundrum

On Wed, 28 Sep 2005 09:43:51 -0300, Derek Broughton
<news@xxxxxxxxxxxxxx> wrote:

>> Now I'm puzzled. I thought SSID b/cast was basically for the benefit of
>> site-survey needs:
>> in other words, if you know the SSID, you don't need
>> it broadcast in order to find the network. I've not seen it mentioned
>> elsewhere that it is needed for normal operations.

Nope. Some really dumb clients can't connect unless they hear the
SSID broadcasts. I bought a no-name PCMCIA card that did that. Even
if you knew the SSID of the access point, it still refused to connect.
However, I think this is the exception rather than the rule and really
should not be a problem with today's clients.

>It's not. If Jeff's guess is right (and they usually are)

I've been wrong before. Caveat Emptor.

>this seems like a
>pretty good reason, to me, to NOT broadcast the SSID.

In my never humble opinion, hiding the SSID is dumb. It screws up a
few clients and make interference detection complicated. For what
little security it adds, it sure makes life difficult for all
involved. It's like hiding your house address from the post office.
Normally, the mail will arrive, but it sure makes it difficult for
everyone else.

>Now you have an easy
>way to see if somebody's extending your signal. What you'd do about it is
>up to you...

It's not too difficult to sniff the traffic and see if there's a
repeater around. You'll see all the packets twice. Once going in,
and once going out. The real problem is that some repeaters (I forgot
which ones) can be set to ANY for the SSID and will regurgitate all
packets, regardless of SSID. I think this feature was invented so
that a single repeater can service multiple networks. Nice idea but
there are complications when it starts regurgitating unwanted packets.

In about 1999, I intentionally installed one of those at a high point
overlooking the downtown area. You could connect to just about any of
the dozen assorted networks. Everyone's range was magically extended
over the entire town. I thought this was cool.

Unfortunately, all the local wireless networks were also having
trouble with what appeared to be co-channel interference. Traffic was
slothish, erratic, and prone to disconnects. Turn off the repeater
and everything was back to normal. Hmmm... Well, when the repeater
literally doubles the amount of traffic in the air, adds everyone
else's traffic to the mess, and guarantees that everyone will have to
wait until the repeater is done sending, then we have interference.
The repeater lasted about 3 days and went back to playing access
point.

I'm still not sure it's a repeater that was causing the SSID to
appear, but I can't think of much else that could do it, other than a
spoofed access point or hacker.

--
Jeff Liebermann jeffl@xxxxxxxxxxxxxxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

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