Listen block

The listen block defines the TCP/IP ports that the IRCd will listen on.

Syntax
listen { /* For IPv4 or IPv6: */ ip ; port ; /* For UNIX sockets: */ file ;

/* Options: */ options { ;		 ;		...	};

/* Specific SSL/TLS configuration to this listen block */ tls-options { ...	}; };

ip
Simply set ip to * (an asterisk) to bind to all available IP's on the machine, OR specify an IP to only bind to that IP address (this latter is usually required at shell providers).

port
This is the port you want to listen on, like 6667. You can also specify a port range, like 6667-6669.

file
This is the full path (filename) to a UNIX socket that will be created on the machine. This feature is rarely used, so if you don't what this is then don't use and don't set it. If you have a file item then you cannot have an ip or port in the same listen block.

options block (optional)
You can specify options for the port. Valid options are:
 * tls: SSL/TLS encrypted port
 * clientsonly: port is only for clients
 * serversonly: port is only for servers
 * websocket: in UnrealIRCd 5 you open up a port for WebSocket support via this. You also need to specify a type, like:

tls-options block (optional)
Valid options are all the SSL/TLS settings that also exist in set::tls. For example you may want to use an Lets Encrypt certificate/key on all normal client ports (via set::tls::certificate). But for this port you want to use another SSL certificate/key: listen { ...       tls-options { certificate "ssl/server.cert.pem"; key "ssl/server.key.pem"; }; };

Example
listen { ip *; port 6667; };

listen { ip *; port 6697; options { tls; }; };