[aprssig] are write-only APRS-IS clients valid?
Pete Loveall AE5PL Lists
hamlists at ametx.com
Mon Dec 2 13:19:03 CST 2013
>From http://www.aprs-is.net/Connecting.aspx (it is not hidden) and has been discussed many times over the past decade on this SIG:
"All core servers and most javAPRSSrvr servers (see the APRS Server page elsewhere on this site) support port 14580 as a user-defined filter port. This port begins by only sending message packets addressed to the client or addressed to stations gated to APRS-IS by the client. As with ALL bidirectional ports, ALL packets passed from the client are passed to APRS-IS on a verified connection (more on that later). Most javAPRSSrvr servers use javAPRSFilter to provide the server-side filtering capability. javAPRSFilter is an additive filter. In other words, you start by receiving almost nothing. When you add a filter, you now receive the original few packets plus the packets that meet your filter definition."
It is not something to "worry" about as it has been a mandatory part of any APRS-IS server since I introduced the limited feed so GUI clients would continue to be able to use APRS-IS. It has continually been mandated (with my strong agreement) by Bob and others to ensure that APRS-IS always fully supports bidirectional communications. Also, it has -nothing- to do with server-side filters other than server-side filters add packets to those described above.
Pete Loveall AE5PL
pete at ae5pl dot net
> -----Original Message-----
> From: Steve Dimse
> Sent: Monday, December 02, 2013 12:59 PM
> This "last heard" table Pete first mentioned in his last communication worries
> me a little. Google says the only mention of "last heard" on aprs-is.net (aside
> from two D-Star and javAPRS mentions) is in the javAPRSSvr manual where
> there is a LastHeardTime parameter, but it seems to work differently than
> the way Pete describes it. There is no mention that an internet packet
> overrides the last heard table, it is documented as a simple time out for
> forgetting about RF stations. Where that dup filtering is done makes a major
> difference and I agree that needs to at least be better documented, but
> better that the consequences of the decision be openly discussed.
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