2d4818e007
With the new control protocol specified in #6461, the client will no longer initiate new connections. Instead, the credentials are generated deterministically by the portal based on the gateway's and the client's public key. For as long as they use the same public key, they also have the same in-memory state which makes creating connections idempotent. What we didn't consider in the new design at first is that when clients roam, they discard all connections but keep the same private key. As a result, the portal would generate the same ICE credentials which means the gateway thinks it can reuse the existing connection when new flows get authorized. The client however discarded all connections (and rotated its ports and maybe IPs), meaning the previous candidates sent to the gateway are no longer valid and connectivity fails. We fix this by also rotating the private keys upon reset. Rotating the keys itself isn't enough, we also need to propagate the new public key all the way "over" to the phoenix channel component which lives separately from connlib's data plane. To achieve this, we change `PhoenixChannel` to now start in the "disconnected" state and require an explicit `connect` call. In addition, the `LoginUrl` constructed by various components now acts merely as a "prototype", which may require additional data to construct a fully valid URL. In the case of client and gateway, this is the public key of the `Node`. This additional parameter needs to be passed to `PhoenixChannel` in the `connect` call, thus forming a type-safe contract that ensures we never attempt to connect without providing a public key. For the relay, this doesn't apply. Lastly, this allows us to tidy up the code a bit by: a) generating the `Node`'s private key from the existing RNG b) removing `ConnectArgs` which only had two members left Related: #6461. Related: #6732.
relay
This crate houses a minimalistic STUN & TURN server.
Features
We aim to support the following feature set:
- STUN binding requests
- TURN allocate requests
- TURN refresh requests
- TURN channel bind requests
- TURN channel data requests
Relaying of data through other means such as DATA frames is not supported.
Building
You can build the relay using: cargo build --release --bin firezone-relay
You should then find a binary in target/release/firezone-relay.
Running
The Firezone Relay supports Linux only. To run the Relay binary on your Linux host:
- Generate a new Relay token from the "Relays" section of the admin portal and save it in your secrets manager.
- Ensure the
FIREZONE_TOKEN=<relay_token>environment variable is set securely in your Relay's shell environment. The Relay expects this variable at startup. - Now, you can start the Firezone Relay with:
firezone-relay
To view more advanced configuration options pass the --help flag:
firezone-relay --help
Ports
By default, the relay listens on port udp/3478. This is the standard port for
STUN/TURN. Additionally, the relay needs to have access to the port range
49152 - 65535 for the allocations.
Portal Connection
When given a token, the relay will connect to the Firezone portal and wait for
an init message before commencing relay operations.
Metrics
The relay parses the OTLP_GRPC_ENDPOINT env variable.
Traces and metrics will be sent to an OTLP collector listening on that endpoint.
It is recommended to set additional environment variables to scope your metrics:
OTEL_SERVICE_NAME: Translates to theservice.name.OTEL_RESOURCE_ATTRIBUTES: Additional, comma-separated key=value attributes.
By default, we set the following OTEL attributes:
service.name=relayservice.namespace=firezone
The docker-init-relay.sh script integrates with GCE.
When OTEL_METADATA_DISCOVERY_METHOD=gce_metadata, the service.instance.id
variables is set to the instance ID of the VM.
Design
The relay is designed in a sans-IO fashion, meaning the core components do not cause side effects but operate as pure, synchronous state machines. They take in data and emit commands: wake me at this point in time, send these bytes to this peer, etc.
This allows us to very easily unit-test all kinds of scenarios because all inputs are simple values.
The main server runs in a single task and spawns one additional task for each allocation. Incoming data that needs to be relayed is forwarded to the main task where it gets authenticated and relayed on success.