Hi HN,<p>Some misbehaving networks drop WireGuard packets either by accident or on purpose. Commonly the latter is done with simple DPI rules that block the handshake initiation [1], but it could be applied to other message types as well.<p>We thought it would be great if there was tool for folks to use as a quick litmus test to see if this happening for them, without having to configure a client to send data through a random, functional WireGuard tunnel to an untrusted remote host. So we built probe.sh.<p>How it works:<p>- The probe.sh web app is an Elixir Phoenix app that spawns a few gen_udp servers across a variety of common UDP ports.
- When a user visits the app, Probe starts a LiveView process and generates a unique cryptographic token to use for the test.
- When the user runs the script shown, it first sends an HTTP request to start the test, followed by a series of UDP payloads, and finally either a complete or cancel request to end the test.
- The UDP payloads are crafted to resemble real world WireGuard packets and sent with widely available tools like netcat (Unix) and System.Net.Sockets.UdpClient (Win) already on your OS.
- The gen_udp server receives these payloads, and if they match one of the four WireGuard message types by header, it broadcasts test updates to the LiveView process for that test, and the test is marked as success.
- The user is immediately shown the results of the test.<p>The entire tool is open source at <a href="https://github.com/firezone/probe">https://github.com/firezone/probe</a> (README contains guide for self-hosting) and you can find a FAQ with more useful info at <a href="https://probe.sh/faq" rel="nofollow">https://probe.sh/faq</a>. You can also see our tally of global results organized by country: <a href="https://probe.sh/stats" rel="nofollow">https://probe.sh/stats</a><p>We hope you find it useful for testing your network for WireGuard connectivity issues.<p>Thanks for reading - feedback welcome!<p>[1] <a href="https://x.com/6h4n3m/status/1459462360003919875" rel="nofollow">https://x.com/6h4n3m/status/1459462360003919875</a>