Copyright (c) 1996,1997,1998,1999,2001,2002,2003,2004,2009,2012,2014 Alan Crosswell

Released under the GNU Public License. See the file COPYING for details.

Alan Crosswell, N2YGK n2ygk@weca.org

Aprsdigi is a specialized Amateur Packet Radio (AX.25) UI-frame digipeater for the Automatic Position Reporting Systems, APRS(tm). It uses the Linux kernel AX.25 network stack as well as the SOCK_PACKET facility to listen for packets on one or more radio interfaces (ports) and repeat those packets -- with several possible modifications -- on the same or other interfaces. Aprsdigi can also use the Internet to tunnel connections among other APRS digipeaters and nodes using IPv4 or IPv6 UDP unicast or multicast.

Aprsdigi implements conventional packet radio AX.25 digipeating, in which a packet is digipeated if the next hop (non-repeated) digipeater ("via") callsign matches the AX.25 port's callsign and sub-station ID (SSID) or an alias callsign and SSID.

There are a number of extensions to conventional digipeating that have been proposed for use in the APRS community. Some of these features have been adopted by Terminal Node Controller (TNC) manufacturers, notably Paccomm and Kantronics. Aprsdigi implements most if not all of the commercialy adopted and proposed features. See the APRS 1.0 Protocol Specification at www.tapr.org for protocol documentation. Aprsdigi attempts to minimally comply with the protocol specification as well as support experimental APRS features. Specific features implemented include:

• Single-interface conventional UI-frame digipeating.
• Cross-interface digipeating (also known as bridging, routing or gatewaying) and one-to-many fanout.
• Substitution of a digipeated alias with the interface's callsign (typically used to substitute RELAY, WIDE or TRACE aliases).
• WIDEn-n flooding algorithm.
• TRACEn-n route recording.
• Mic-Encoder(tm) support, including SSID-based digipeating, decompression of packets into the conventional APRS MIM format. (The Mic-Encoder compression is also used by other products such as the Kenwood TH-D7A and D700, and TAPR PIC-Encoder).
• TheNet X1J4 node beacon text translation (removal of the lqTheNet X1J4 (alias)rq prefix from the btext).

The official place where new versions are found is:

https://github.com/n2ygk/aprsdigi

Others may mirror this stuff elsewhere, but I only promise that the latest will be at the above site.

If you are not a member of Tucson Amateur Packet Radio (TAPR), consider joining! See www.tapr.org

See the aprsdigi.8 and aprsmon.1 man pages. Aprsdigi is an intelligent digipeater (see the APRS Protocol Reference, ISBN 0-9644707-6-4, at http://www.tapr.org).

Aprsmon is deprecated in favor of Dale Heatherington's aprsd, http://sourceforge.net/projects/aprsd/.

See the file INSTALL for installation instructions.

See the file NEWS for latest news.