Do you encrypt your wireless?  WEP isn't sufficient to prevent a
determined attacker from decrypting your traffic (sensitive
communications should be using HTTPS, even if wireless encryption is
also used...), but it *does* require a PSK (Pre-Shared Key -- i.e., a
password) to join the network.  (The TrueCrypt I've heard of encrypts
the data on a drive, but does nothing to secure it in transmission (and
so isn't relevant for this), but there might be an Australian product
using that name that does something different.

  Your wireless router should be able to show you a list of currently
connected clients, with at least the wireless MAC address of each and
perhaps additional information such as signal strength, traffic volume,
etc.  It shouldn't be too difficult to identify your devices on this
list and see what that leaves.
  If you have a small laptop (I use a netbook for this), you may be able
to use software such as NetStumbler or InSSIDer to search for devices
associating to your SSID and track them down by seeing how their signal
strength changes as you move in different directions.  (Note that this
may bring you face-to-face with the responsible party....)
  I used to use NetStumbler for this, but it seems that lately my
devices have wireless chips in them that NS hasn't been updated to
support.  InSSIDer appears to take a less low-level approach and so be
more hardware-independent -- it's from the makers of the "Wi-Spy" USB
spectrum analyzer, which can be helpful in tracking down interference
from non-wifi sources.
  You could also consider switching to 802.11a, which uses the 5GHz band
instead of 2.4GHz.  'a' gear tends to be a bit more expensive and a bit
more power-hungry, but only devices with a 5GHz radio will even see it,
and that probably won't include your "leech".

David Gillett
CISSP CCNP



-------- Original Message --------
From: Robert <[log in to unmask]>

I have for a long time had suspicions that somebody is logging in to my
home
Wifi network and using my download allowance. I have used all the
appropriate settings in the router and use Truecrypt to avoid anybody
accessing my private information, banking details, passwords etc. I am
looking for any software which could tell me if outsiders have found a
way
to use my internet connection. I have a D-link router with 2 wireless PC
connections and one usb connection. Any suggestions ??

Bob Weaver


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