[aprssig] Recommended Behavior for Read-Only APRS-IS Clients?

Kenneth Finnegan kennethfinnegan2007 at gmail.com
Sun Apr 19 10:07:02 CDT 2015

> If it is not there, don't "read between the lines" thinking that it was just left out; it wasn't.

Well if you're going to claim that the APRS-IS spec is infallible,
then let's really dig into it then.

The only line I see regarding keep-alive reads as follows:

> Most servers will also periodically send lines beginning with a # to check the connection if there has been no activity on the TCP port.

What is this time period? How long should my client wait before
concluding an APRS-IS connection is dead and reset it? Should my
client not implement an L5 timeout at all and only depend upon the
same L4 timeout that you claim the server uses?

If APRS-IS clients truly should not send keep-alive packets, then how
do I reconcile this with the existence of the "ClientTimeout"
parameter in the aprsc configuration? A default install of aprsc sheds
silent clients after 48 hours (regardless of their verified status, I
tested this by changing the default "ClientTimeout 48h" to
"ClientTimeout 25s"). What L5 keep-alive is aprsc expecting? Has this
been disabled on all the rotate.aprs.net servers? www.aprs-is.net does
not say "APRS-IS servers must not implement L5 timeouts," so this
aprsc behavior seems perfectly valid to me.
Kenneth Finnegan, W6KWF

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