catbox is an IRC server with a focus on being small and understandable. The goal is security.

Features

Server to server linking
IRC operators
Private (WHOIS shows no channels, LIST isn't supported)
Flood protection
K: line style connection banning
TLS

catbox implements enough of RFC 1459 to be recognisable as IRC and be minimally functional. I likely won't add much more and don't intend it to be complete. If I don't think something is required it likely won't be here.

Installation

Download catbox from the Releases tab on GitHub, or build from source (go build).
Configure catbox through config files. There are example configs in the conf directory. All settings are optional and have defaults.
Run it, e.g. ./catbox -conf catbox.conf. You might run it via systemd via a service such as:

[Service]
ExecStart=/home/ircd/catbox/catbox -conf /home/ircd/catbox/catbox.conf
Restart=always

[Install]
WantedBy=default.target

Configuration

catbox.conf

Global server settings.

opers.conf

IRC operators.

servers.conf

The servers to link with.

users.conf

Privileges and hostname spoofs for users.

The only privilege right now is flood exemption.

TLS

A setup for a network might look like this:

Give each server a certificate with 2 SANs: Its own hostname, e.g. server1.example.com, and the network hostname, e.g. irc.example.com.
Set up irc.example.com with DNS round-robin listing each server's IP.
List each server by its own hostname in servers.conf.

Clients connect to the network hostname and verify against it. Servers connect to each other by server hostname and verify against it.

Why the name?

My domain name is summercat.com, cats love boxes, and a tribute to ircd-ratbox, the IRC daemon I used in the past.

horgh/catbox