# Server links

echoIRCd links to other servers — and to echo services — over a standard server-to-server
protocol, wire-compatible with the InspIRCd 1206 protocol.

## Server identity

Every server needs a unique **SID** (three characters, the first a digit) and a name.

```ini
network "echoiRCd";
sid     "0AA";
```

## A link block

Each `link` block describes a peer: its name, address, port, and the passwords used to
authenticate the connection in each direction.

```ini
listen { ip "[::]"; port 7700; type server; }

link {
    name         "hub.example.net";
    ip           "203.0.113.10";
    port         7700;
    sendpassword "outbound-secret";
    recvpassword "inbound-secret";
}
```

> Treat link passwords as secrets, and restrict the server port to trusted peers.

## Services

echo services connect as a special linked server. In the ircd, mark the services server name as a
**U-lined** server (and as the SASL server) so its privileged commands and SASL relay are
accepted:

```ini
uline { server "services.echoircd.org"; }
sasl_server "services.echoircd.org";
```

See [Services](/docs/services) for the services side of the link.