User wifi question: blacklisting/ignoring SSIDs?

[Keith Lofstrom <keithl kl-ic com>]

Can the wifi portion of network manager be instructed
to ignore particular SSID strings, in particular,
"xfinity"?  

Here in Portland Oregon, many businesses, nonprofits,
and individuals offer open wifi free to the public.
My own access point broadcasts "www.personaltelco.net"
like dozens of others in the Portland area, but there
are thousands of open WAPs, with thousands of different
SSIDs.  

Internet provider Comcast gives wireless access points
to their customers configured with the SSID "xfinity",
which allows comcast customers to use each other's wifi,
but this "service" is not available to the general public,
nor would privacy-savvy users want to be tracked by
Comcast if it was.  Indeed, offering open wifi service to
the general public violates Comcast's service contract.

However, if xfinity is the strongest non-WEP/WPA beacon
in a previously-unvisited location, that is the SSID
network manager wifi attaches to first.  After all, it
tried and succeeded before, with a different xfinity 
beacon.  Much fumbling and gnashing of teeth to find a
different open network, while network manager repeatedly
interrupts the manual search and connects to xfinity
again, like a yellowjacket wasp to a picnic.

So, is there an easy way to create a list of SSIDs that
network manager should always ignore?  I haven't found
another internet provider that I dislike as much as
Comcast, but it is prudent to allow for more than one.

Keith

-- 
Keith Lofstrom          keithl keithl com