tailscale/cmd/lopower

Tailscale LOPOWER

"Little Opinionated Proxy Over Wireguard-encrypted Routes"

STATUS: in-development alpha (as of 2024-11-03)

Background

Some small devices such as ESP32 microcontrollers support WireGuard but are too small to run Tailscale.

Tailscale LOPOWER is a proxy that you run nearby that bridges a low-power WireGuard-speaking device on one side to Tailscale on the other side. That way network traffic from the low-powered device never hits the network unencrypted but is still able to communicate to/from other Tailscale devices on your Tailnet.

Diagram

Features

• Runs separate Wireguard server with separate keys (unknown to the Tailscale control plane) that proxy on to Tailscale
• Outputs WireGuard-standard configuration to enrolls devices, including in QR code form.
• embeds tsnet, with an identity on which the device(s) behind the proxy appear on your Tailnet
• optional IPv4 support. IPv6 is always enabled, as it never conflicts with anything. But IPv4 (or CGNAT) might already be in use on your client's network.
• includes a DNS server (at fd7a:115c:a1e0:9909::1 by default and optionally also at 10.90.0.1) to serve both MagicDNS names as well as forwarding non-Tailscale DNS names onwards
  • if IPv4 is disabled, MagicDNS A records are filtered out, and only AAAA records are served.

Limitations

• this runs in userspace using gVisor's netstack. That means it's portable (and doesn't require kernel/system configuration), but that does mean it doesn't operate at a packet level but rather it stitches together two separate TCP (or UDP) flows and doesn't support IP protocols such as SCTP or other things that aren't TCP or UDP.
• the standard WireGuard configuration doesn't support specifying DNS search domains, so resolving bare names like the go in http://go/foo won't work and you need to resolve names using the fully qualified go.your-tailnet.ts.net names.
• since it's based on userspace tsnet mode, it doesn't pick up your system DNS configuration (yet?) and instead resolves non-tailnet DNS names using either your "Override DNS" tailnet settings for the global DNS resolver, or else defaults to 8.8.8.8 and 1.1.1.1 (using DoH) if that isn't set.

TODO

• provisioning more than one low-powered device is possible, but requires manual config file edits. It should be possible to enroll multuple devices (including QR code support) easily.
• incoming connections (from Tailscale to lopower) don't yet forward to the low-powered devices. When there's only one low-powered device, the mapping policy is obvious. When there are multiple, it's not as obvious. Maybe the answer is supporting 4via6 subnet routers.

Installing

• git clone this repo, switch to lp branch, go install ./cmd/lopower and see lopower --help.