syncthing/cmd/relaysrv/README.md

relaysrv
========

[![Latest Build](http://img.shields.io/jenkins/s/http/build.syncthing.net/relaysrv.svg?style=flat-square)](http://build.syncthing.net/job/relaysrv/lastBuild/)

This is the relay server for the `syncthing` project.

To get it, run `go get github.com/syncthing/relaysrv` or download the
[latest build](http://build.syncthing.net/job/relaysrv/lastSuccessfulBuild/artifact/)
from the build server.

:exclamation:Warnings:exclamation: - Read or regret
-----

By default, all relay servers will join the default public relay pool, which means that the relay server will be availble for public use, and **will consume your bandwidth** helping others to connect.

If you wish to disable this behaviour, please specify `-pools=""` argument.

Please note that `relaysrv` is only usable by `syncthing` **version v0.12 and onwards**.

To run `relaysrv` you need to have port 22067 available to the internet, which means you might need to allow it through your firewall if you **have a public IP, or setup a port-forwarding** (22067 to 22067) if you are behind a router.

Furthermore, **by default relaysrv will also expose a /status HTTP endpoint on port 22070**, which is used by the pool servers to peek at metrics of the relaysrv, such as what are the current transfer rates, how many clients are connected, etc, etc. If you wish this information to be available, similarlly you might want to allow it through your firewall, or port-forward it (22070 to 22070) on your NAT device.

This is **not mandatory** for the relaysrv to function, and is used only to gather metrics and present them in the overview page of the pool server, displaying stats about the specific relay.

At the point of writing the endpoint output looks as follows:

```
{
    "bytesProxied": 0,
    "goArch": "amd64",
    "goMaxProcs": 1,
    "goNumRoutine": 13,
    "goOS": "linux",
    "goVersion": "go1.6",
    "kbps10s1m5m15m30m60m": [
        0,
        0,
        0,
        0,
        0,
        0
    ],
    "numActiveSessions": 0,
    "numConnections": 0,
    "numPendingSessionKeys": 2,
    "numProxies": 0,
    "options": {
        "global-rate": 0,
        "message-timeout": 60,
        "network-timeout": 120,
        "per-session-rate": 0,
        "ping-interval": 60,
        "pools": [
            "https://relays.syncthing.net/endpoint"
        ],
        "provided-by": ""
    },
    "startTime": "2016-03-06T12:53:07.090847749-05:00",
    "uptimeSeconds": 17
}
```

If you wish to disable the /status endpoint, provide `-status-srv=""` as one of the arguments when starting the relaysrv.

Running for public use
----
Make sure you have a public IP with port 22067 open, or make sure you have port-forwarding (22067 to 22067) if you are behind a router.

Run the `relaysrv` with no arguments (or `-debug` if you want more output), and that should be enough for the server to join the public relay pool.
You should see a message saying:
```
2015/09/21 22:45:46 pool.go:60: Joined https://relays.syncthing.net/endpoint rejoining in 48m0s
```

See `relaysrv -help` for other options, such as rate limits, timeout intervals, etc.

Running for private use
-----

Once you've started the `relaysrv`, it will generate a key pair and print an URI:
```bash
relay://:22067/?id=EZQOIDM-6DDD4ZI-DJ65NSM-4OQWRAT-EIKSMJO-OZ552BO-WQZEGYY-STS5RQM&pingInterval=1m0s&networkTimeout=2m0s&sessionLimitBps=0&globalLimitBps=0&statusAddr=:22070
```

This URI contains partial address of the relay server, as well as it's options which in the future may be taken into account when choosing the best suitable relay out of multiple available.

Because `-listen` option was not used, the `relaysrv` does not know it's external IP, therefore you should replace the host part of the URI with your public IP address on which the `relaysrv` will be available:

```bash
relay://123.123.123.123:22067/?id=EZQOIDM-6DDD4ZI-DJ65NSM-4OQWRAT-EIKSMJO-OZ552BO-WQZEGYY-STS5RQM&pingInterval=1m0s&networkTimeout=2m0s&sessionLimitBps=0&globalLimitBps=0&statusAddr=:22070
```

If you do not care about certificate pinning (improved security) or do not care about passing verbose settings to the clients, you can shorten the URL to just the host part:

```bash
relay://123.123.123.123:22067
```

This URI can then be used in `syncthing` as one of the relay servers.

See `relaysrv -help` for other options, such as rate limits, timeout intervals, etc.

Other items available in this repo
----
##### testutil
A test utility which can be used to test connectivity of a relay server.
You need to generate two x509 key pairs (key.pem and cert.pem), one for the client, another one for the server, in separate directories.
Afterwards, start the client:
```bash
./testutil -relay="relay://uri.of.relay" -keys=certs/client/ -join
```

This prints out the client ID:
```
2015/09/21 23:00:52 main.go:42: ID: BG2C5ZA-W7XPFDO-LH222Z6-65F3HJX-ADFTGRT-3SBFIGM-KV26O2Q-E5RMRQ2
```

In the other terminal run the following:

```bash
 ./testutil -relay="relay://uri.of.relay" -keys=certs/server/ -connect=BG2C5ZA-W7XPFDO-LH222Z6-65F3HJX-ADFTGRT-3SBFIGM-KV26O2Q-E5RMRQ2
```

Which should then give you an interactive prompt, where you can type things in one terminal, and they get relayed to the other terminal.

Relay related libraries used by this repo
----
##### Relay protocol definition.

[Available here](https://github.com/syncthing/syncthing/tree/master/lib/relay/protocol)


##### Relay client

Only used by the testutil.

[Available here](https://github.com/syncthing/syncthing/tree/master/lib/relay/client)