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Re: [aprsisce] Tricks with IS-Server Port Filters

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  • Randy Love
    Snazzy... and only available to APRSISCE/32 users too! WF5X
    Message 1 of 2 , Jul 29, 2011
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      Snazzy... and only available to APRSISCE/32 users too! 

      WF5X

      On Fri, Jul 29, 2011 at 5:08 PM, Lynn W Deffenbaugh (Mr) <kj4erj@...> wrote:
       

      Ok, here's an advanced topic for those of you that understand netmasks,
      telnet, APRS-IS server, and filters.

      Consider the following filter (Note that this is only supported by
      APRSISCE/32, not the general APRS-IS server):

      b/* -e/*

      What do you think that would do? If you guessed that it would give you
      all the packets received on an RF port and exclude all packets received
      via APRS-IS, you'd be correct. You can see this with Control-G
      (FilterTest) and enter that filter, a handy way to get a window that
      shows the RF-received packets, and ONLY the RF-received packets (well,
      with a bit of filter-cruft at the front of each line).

      Now, what good is that information? Well, have you ever wanted a way to
      remotely see what packets your IGate is hearing? Real-time and without
      any APRS-IS duplicate filtering? Here's how:

      1) Configure a local IS-Server port in your IGate instance. It'll be
      TCP/IP on 0.0.0.0 on an available port of your choosing. (If you want
      it to only work from the same machine, use 127.0.0.1. If you want it to
      work only from your LAN, use the IP address of that machine on your
      LAN. 0.0.0.0 will accept inbound connections from any IP address like
      from the Internet if your firewall allows it, remember to open the port
      you've chosen.) (This is the part that requires you to understand
      netmasks and ports and binding of sockets to ports).

      2) From any machine that has access to the IP address you gave to the
      IS-Server port, telnet to that server and port. For command-line
      telnet, the command would be "telnet IPAddress Port" for example, for me
      to connect to APRSISCE on my WiFi-connected phone instance which is
      listening on port 14580, I'd use "telnet 192.168.10.187 14580". (This
      is the part that wants you to understand telnet).

      3) Enter the APRS-IS logon string like "user YOURCALL-SSID pass -1" and
      hit enter. Of course, use your own callsign-SSID (nearly any -SSID will
      work since APRSISCE/32 doesn't reject duplicate connections). The
      password is required by doesn't need to be valid for the callsign
      because we're just going to listen anyway. After this, you should start
      getting heartbeats from the server.

      4) Enter the filter above with the command "#filter b/* -e/*" and hit
      enter. You should now start receiving all RF-received (non-APRS-IS)
      packets from your IGate!

      How does this work? b/* says to make the whole world your buddy and get
      all packets (APRS-IS requires at least one character before the *,
      APRSISCE/32 supports total wildcards). The e/ filter is the "entry"
      filter that checks the path component following the qA construct. The *
      again matches any station doing the entry and the leading minus (-)
      makes that filter term an exclusion clause.

      Yes, you can monitor your IGate's RF reception from anywhere that can
      connect to the IGate's port. Pretty powerful, huh?

      Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32


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