AXLink v0.2.0-alpha.1

Prerelease. Tested in the lab (simulated radio channel, real kernel IP stacks) and in CI,
where the network adapter passes a ping test on Linux, Windows and macOS. Not yet on the air
with a real radio. Try it on the bench first.

AXLink turns a KISS radio into a network adapter: ordinary programs (ping, browsers, SSH, small
web servers) talk over AX.25 UI frames at 1200 baud. Tuned to the Quansheng UV-K1 / UV-K5 V3 with
the F4HWN firmware and its KISS TNC app, or our AXLink TNC
with ACKMODE; any KISS TNC works.

Start here: QUICKSTART.md
(Linux, Windows, macOS).

What is in it

• Network adapter on Linux, Windows (Wintun) and macOS (utun); IPv4 over AX.25 UI/PID 0xCC.
• Stations find each other by short beacons, no routes to configure.
• Web interface in English and German on 127.0.0.1:7373: live monitor, stations heard with
  locator and distance, settings that are stored.
• Chat as APRS messages straight over the radio, no IP: messages to a station (acknowledged,
  repeated, kept in a mailbox until the station is heard again) and a CQ room. Radios with the
  APRS messenger firmware speak the same format.
• Mesh: a station switched to "Relay" repeats frames; beacons and CQ travel over up to two
  relays, and stations learn the way to each other.
• Internet gateway: a station shares its internet connection as an HTTP proxy (HTTPS through
  CONNECT); clients choose it in the web interface.
• Firewall on by default, refusals answered at once; port forwarding of a service of the
  own network; a welcome page per station.

Lab numbers (model of the F4HWN KISS app, not a radio): ping about 2.1 s round trip, a small
HTTP file in 9 s, a chat message acknowledged in 3-5 s; over a relay ping about 5 s and HTTP
about a minute.

Packages

File	For
axlinkd-0.2.0-alpha.1-linux-amd64.tar.gz	Linux PCs
axlinkd-0.2.0-alpha.1-linux-arm64.tar.gz	64-bit Raspberry Pi OS and other ARM64 Linux
axlinkd-0.2.0-alpha.1-linux-armv6.tar.gz	every Raspberry Pi, 32-bit (Pi Zero W too)
axlinkd-0.2.0-alpha.1-windows-amd64.zip	Windows 10/11 PCs; contains wintun.dll 0.14.1 and its licence
axlinkd-0.2.0-alpha.1-windows-arm64.zip	Windows on ARM; contains wintun.dll 0.14.1 and its licence
axlinkd-0.2.0-alpha.1-macos-arm64.tar.gz	Macs with Apple silicon
axlinkd-0.2.0-alpha.1-macos-amd64.tar.gz	Intel Macs
SHA256SUMS	checksums of all files

The programs are not signed: Windows SmartScreen warns, macOS needs
xattr -d com.apple.quarantine axlinkd once.

Known limits

• No test with radios yet; the numbers above come from a model.
• Stations that do not hear each other collide at a relay (hidden stations); TCP and the chat
  repeat what is lost, at the cost of time.
• 1200 bit/s is shared by all stations on the frequency: a few kilobytes take tens of seconds,
  an HTTPS set-up a minute or two.
• Windows treats the adapter as a public network and blocks incoming connections in its own
  firewall unless a rule allows them.

Use your own callsign; placeholders are refused. Every operator is responsible for what is
allowed on their frequency. Licence: GPL-3.0-or-later with an additional permission for Wintun;
protocol specifications CC BY 4.0. Changes: CHANGELOG.md.