OPT-OUT.TXT           OPT-OUT CONSIDERATIONS in APRS
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Document version: 8.4.7
Document dated:   1 Sept 200
Author(s):        Bob Bruninga, WB4APR 
ABSTRACT
AEA.TXT           OPT-OUT issues and details
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Ever since I came up with the APRS idea, there has always been concern
expressed by a minority over the "Big Brother" issue of letting everyone
anywhere see what you are doing on APRS.  This issue was magnified to
explosive magnitudes with the integration of APRS to the internet.
Although there is no such thing as privacy on Amateur radio, there has
always been the idea of using the minimum power to get the message
across.  Also, hams frequently switch to simplex to pass somewhat
sensitive information where the reduction in range is on the
order of 10 to one resulting in a capture area reduction of 100 to 1.

When Steve Dimse implemented FINDU.COM which then began archiving every
packet heard on APRS worldwide for permanent archiving and retrieval
by anyone at any time, this issue of "Big Brother" or the PUBLIC
nature of amateur radio communications rose again.  For the sake of
the loud minority and to avoid continuous debate over the issue, he
allowed for an OPT-OUT mechanism so that users could indicate in their
packets that they did not desire their packets to be permanently archived.
This is done with a "!x!" in the packet text or by the use of the "X"
overlay character in position packets.

This then lead the debate over to whether the users should be able to
also OPT-OUT of the Internet completely, so that they could indicate
that they did not want their packets to be distributed worldwide if
they wanted to.  Since everything on HAM radio is public, there are
very strong opinions on either side of the debate.

The proposal was for all IGates to ignore any packet with "NOGATE" in
its path.  This solution is backwards compatible to all user software
and hardware, but needs to be implemented at the IGates to be
effective.

There seems to be no consensus at hand, and unless/until the IGate
authors agree to honor the NOGATE requests, there will probably
be no near term OPT-OUT option implemented at the IGates.

Rather than take sides, it seems to me that it is simply a matter of
choice.  SO to allow that small minority that wants to OPT-OUT of the
IGates, I have added an OPT-OUT mechanism in APRSdos if  they want
to use it.

The OPT-OUT in APRSdos takes advantage of a weakness in the IGate
implementation that uses the presence of the "3rd party" format
in a LOOP-CHECK algorithm to eliminate Igate-to-RF-to-IGate loops.
While the proper IGate loop-filter should have been implemented
around checking for the presence of the "TCPIP" or "TCPxx" path in
all headers, it wasnt, and that argument is beyond the scope of this
file.  THus if a user wants to OPT-OUT of the entire IGate system,
then he simply needs to transmit his packets in the 3rd party format,
and the IGates will ignore him.

So, to place your packets in APRSdos format.  Simply toggle on the
alt-SETUP-FORMATS-OPT-OUT command.  ALso notice that all APRSdos
ZIP-LAN packets have always been in 3rd party and are therefore
always ignored by the Igates (This is why I am opposed to 3rd party
format being the LOOP filter mechanism!)...

bob

