enricobuehler
54b75c9be4
Follows the security audit (#5/#9): the GameStream-compat plane carries inherent on-path weaknesses that can't be fixed on the wire without breaking stock Moonlight — its pairing runs over plain HTTP (#9, MITM-able during the pairing window) and its legacy control encryption can reuse GCM nonces (#5, a passive eavesdropper can recover/forge input). The native punktfunk/1 plane (SPAKE2 PIN pairing + per-direction AEAD nonces) has neither. So flip the default to secure-by-default: - `serve` → native punktfunk/1 plane + management API ONLY (no GameStream surface). - `serve --gamestream` → ALSO the GameStream/Moonlight-compat planes (nvhttp pairing, RTSP, ENet control, _nvstream mDNS). Opt-in, logged with a trusted-LAN caveat. `--moonlight` is an alias. - The native plane is now ALWAYS on in `serve` (`--native` is a kept-for-compat no-op); the unified GameStream+native host is `serve --gamestream`. `gamestream::serve` gates the GameStream spawns (nvhttp/rtsp/control/mdns) on the flag; the native plane + mgmt + native-pairing handle always run. To avoid silently regressing validated Moonlight deployments, the explicit deployment configs PRESERVE Moonlight via `--gamestream` (each documents dropping it for a secure native-only host): the Linux systemd unit, the Steam Deck installer, and the Windows service default (DEFAULT_HOST_CMD). The bare `serve` default (new/manual use) is secure. Docs swept to match (host-cli, moonlight, quickstart, install, packaging READMEs, CLAUDE.md, README, …): Moonlight setup now instructs `--gamestream`; native/console refs use bare `serve`. OpenAPI regenerated (a stale "run `serve --native`" string). fmt + clippy clean; 94 host tests green. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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title, description
| title | description |
|---|---|
| Pairing & Trust | How a client and host establish trust — PIN pairing once, pinned reconnects after. |
punktfunk has no accounts and no cloud. Trust is established directly between a client and a host, on your network, with a one-time pairing — either an approval click in the host's console or a PIN ceremony. After that, the device reconnects automatically on a pinned cryptographic identity.
How it works
- Each host has a stable identity (a certificate). Clients remember its fingerprint, so they know they're talking to the same host next time.
- The first time a client connects, you pair it: the host shows a short 4-digit PIN, you type it into the client, and a secure exchange (SPAKE2) binds the two identities. An attacker who doesn't know the PIN gets a single online guess — no offline cracking.
- After pairing, the host stores the client's identity in its allow-list, and the client stores the host's fingerprint. Reconnects are automatic — no PIN.
Approving a device from the console (no PIN)
The fastest way to admit a new device: just try to connect from it. On a pairing-required host, the attempt shows up in the web console's Pairing page under Waiting for approval — with the device's name and identity fingerprint. Click Approve (and optionally give it a label like "Living Room TV"), and the device is paired on the spot: its next connect goes straight through. No PIN to read or type.
Deny just dismisses the request (the device can knock again later — it's "not now", not a blocklist). Requests expire on their own after a few minutes.
This works because approval happens on the host's authenticated management surface — only someone with console access can admit a device.
Pairing with a PIN
PIN pairing is the default and required path for any new host: unless the host has explicitly opted into trust-on-first-use (see below), a client connecting to an unknown host must complete the PIN ceremony before it can stream. It's the right path for the first device (before the console has admitted anything) or when you're at the client and the console isn't handy.
Pairing has to be armed on the host before a client can pair (so a random device can't pair
itself). On the production host (serve), this is done from the web console: open the
host's management console, click to arm pairing, and the host displays a 4-digit PIN along with the
list of paired devices. This works on a headless host over the network — there is no command-line flag
to arm pairing on serve.
(The standalone headless test host, punktfunk1-host, takes --allow-pairing/--require-pairing on its
command line instead; the production serve host arms pairing from the console.)
Then, on the client:
- Native clients (Apple, Linux, Windows, Android): select the host (or use Pair with PIN… from its menu) and enter the PIN the host displays.
- Moonlight: choose Pair; Moonlight shows the PIN to confirm on the host side.
Requiring pairing (the default)
By default, the native host requires pairing — only devices that have paired can stream. This is the right setting on a shared network: a device has to complete the PIN ceremony once before it can connect.
If you're on a fully trusted single-user network and want to skip pairing, run the host open with
serve --open (or punktfunk1-host --allow-tofu for the standalone host) — it then advertises
pair=optional and accepts unpaired clients. Requiring pairing is strongly recommended.
Trust-on-first-use (host opt-in)
Trust-on-first-use (TOFU) is off by default and is an explicit host opt-in for fully trusted
networks. A host enables it by running open — punktfunk1-host --allow-tofu or serve --open — which makes
it advertise pair=optional over mDNS and accept unpaired clients. Only then does a client offer the
TOFU path: connecting to such a host for the first time shows the host's fingerprint and asks you to
confirm it (compare it with the one the host logged at startup), then pins it. The client presents
this clearly as the reduced-security option, alongside Pair with PIN.
Warning: TOFU cannot detect an impostor on the first connection — if someone is impersonating the host the very first time you connect, you'll pin the attacker's fingerprint. PIN pairing closes that gap (the SPAKE2 ceremony binds both identities), which is why it's the default. Use TOFU only on a network you fully trust.
For every other case — a host advertising pair=required (the default), a host you typed in by hand,
or a discovered host whose pair policy is unknown — TOFU is not offered and the client routes straight
to the PIN ceremony.
Once a host is pinned, a fingerprint change is treated as the impostor signal: the client forces re-pairing through the PIN ceremony rather than offering to re-trust the new identity.
Managing paired devices
The web console lists every paired device and lets you remove one (revoking its access). Re-pairing is just the PIN ceremony again.