OT: ADSL safe practices and setting up a home network

[Guy Fraser]

On Fri, 2006-14-04 at 13:01 -0500, Mike McCarty wrote:
> Anne Wilson wrote:
> > On Friday 14 April 2006 15:47, Mike McCarty wrote:
> > 
> > Your choice entirely.  Encryption does work, and I also have checked that 
> > nothing is detectable outside my boundaries.  Then of course it can be tied 
> > to mac addresses.  It's perfectly possible to have the facility without risk.  
> > If you don't need it, fine.
> 
> Any machine to which there is physical access has only
> relative security. The fewer physical access points there
> are the higher the relative security can be. Removing the
> antenna almost removes one of the access points.
> 
> I say almost because, should the firmware or hardware not
> properly disable the wireless I/F, someone who knew I was
> here and had a high-power transmitter and a focussed high
> gain antenna with a sensitive receiver could still get
> access.
> 

Very true. Removing the antenna may not actually do what 
you want, it will certainly reduce the antenna gain, but 
does not prevent transmission or reception. What you 
should do is install a 50 Ohm shielded terminator. You 
will need a BNC adaptor for you antenna connector, which 
could be a a TNC, SMA, Reverse TNC, Reverse SMA or other 
similar type connector. You should bring your antenna 
with you to make sure you get the right one. You can 
likely get the adaptor and terminator at an electronics 
supply store, or from a radio system installer.

We used to do a lot of wireless connections and determined 
that even heavily shielded radios could communicate 
effectively over a couple feet with no antennae installed 
on either one. We also determined that using 100mW TX
power and 6 foot solid parabolic dishes they could 
communicate reliably upto 40 miles between 200 foot 
towers. It would be reasonable to interpolate that with 
a 20 inch parabolic antenna at one end and no antenna 
at the other end, you could reliable connect over a few 
dozen feet {power is dissipated using an inverse square 
law}. Using a high quality receiver and flat panel antenna 
arrays it could be possible to receive a signal covertly 
from hundreds of feet away, but then you don't necessarily 
need a wireless router to do that anyway.;^) If you are 
interested, there are a few good articles about Tempest 
surveillance that are enlightening. I used to work on 
anti-tempest compliant devices for law enforcement and 
military applications, back in the late 80's. I can only 
imagine how much better the new tempest stuff is. :^O