In my spare time, I'm working on a layer 4 app for Caddy that I call Project Conncept. It routes raw TCP/UDP streams using composable handlers, much like how Caddy's HTTP server is configured.
When I started working on this, it was available only to sponsors, but now it is available to the public:
Click here for the code: https://github.com/mholt/caddy-l4
Like the HTTP app, layer 4 routes consist of matchers and handlers; if a route's matchers match the properties of the connection or first few bytes of the stream, its handlers will be invoked, one after another. This enables a great degree of flexibility when composing routes.
You can match on more than just client IPs and protocols. For example, all existing HTTP matchers can be used in layer 4 routes with the same degree of efficiency as the HTTP server. Similarly, you can also use any existing TLS connection matchers.
As with all other Caddy configurations, you can change it while it is running using Caddy's on-line config API.
✨And of course, all certificates used for TLS termination are fully-managed in regular Caddy fashion.
💚 Become a sponsor (or advocate for your company to sponsor) to continue development: https://github.com/sponsors/mholt -- thank you!