What is ElixIRCd?

Overview

ElixIRCd is a full IRC server (IRCd) daemon written in Elixir, a functional, concurrent programming language that runs on the Erlang virtual machine (BEAM). It is designed to provide a robust and highly concurrent environment for running IRC networks.

Unlike many legacy IRC daemons written in C, ElixIRCd takes advantage of:

• BEAM process model — each user connection is an isolated lightweight process
• Mnesia in-memory database — all server state (users, channels, bans) lives in an ETS-based in-memory store with no disk persistence between restarts
• OTP supervision trees — automatic process restart and fault isolation
• Elixir’s functional nature — immutable data and pattern matching for predictable behavior

What It Implements

ElixIRCd is a single-server IRC daemon. It implements:

Category	Details
IRC Protocol	RFC 1459, RFC 2810, RFC 2811, RFC 2812, RFC 2813, RFC 7194
IRCv3 Capabilities	SASL, account-tag, account-notify, away-notify, chghost, extended-join, invite-notify, multi-prefix, message-tags, server-time, msgid, monitor, setname, uhnames, extended-uhlist, client-tags, sts, cap-notify, invite-extended
Integrated Services	NickServ (nickname registration) and ChanServ (channel registration)
Transports	TCP, TLS, WebSocket (HTTP), WebSocket (HTTPS/WSS)
Authentication	SASL PLAIN, NickServ password authentication
Security	Hostname cloaking, rate limiting, SSL/TLS

What It Does NOT Implement

It is important to understand what is not in scope for the current version:

• Server-to-server (S2S) linking — ElixIRCd runs as a single-server IRC network. There is no spanning tree, no server federation, and no S2S protocol support
• Horizontal scalability — cannot be clustered across multiple machines
• BATCH capability — IRCv3 batch is not implemented
• Echo-message — clients do not receive copies of their own messages via IRCv3
• Labeled-response — not implemented
• WHOX (extended WHO) — the advanced WHO query format is not supported

Architecture Summary

┌──────────────────────────────────────────────────────┐
│                     ElixIRCd                         │
│                                                      │
│  Listeners (ThousandIsland / Bandit)                 │
│   TCP :6667  TLS :6697  WS :8080  WSS :8443          │
│                    │                                 │
│  Connection Handler (per user, BEAM process)         │
│   ├── Handshake (DNS, ident, welcome sequence)       │
│   ├── CAP Negotiation + SASL Authentication          │
│   ├── Command Dispatcher                             │
│   └── Rate Limiter                                  │
│                    │                                 │
│  In-Memory State (Mnesia/ETS)                        │
│   ├── Users, Channels, UserChannels                  │
│   ├── Bans, Exceptions, Invites, Invex               │
│   ├── NickServ / ChanServ registrations              │
│   ├── SASL Sessions                                  │
│   └── Monitor targets                               │
│                    │                                 │
│  IRC Services                                        │
│   ├── NickServ                                       │
│   └── ChanServ                                       │
│                    │                                 │
│  Background Jobs                                     │
│   ├── Nick expiration                                │
│   ├── Channel expiration                             │
│   ├── Unverified nick cleanup                        │
│   ├── SASL session expiration                        │
│   └── Verification email delivery                   │
└──────────────────────────────────────────────────────┘

Note

All state is stored in-memory. Restarting the server clears all user sessions, but registered nicknames and channels are persisted through Mnesia’s ETS tables which survive in-process restarts but not application restarts unless Mnesia disk persistence is configured.

In the default configuration, registered nicks and channels are lost on full server restart. For production, consider Mnesia disk tables or regular state export.

IRC Protocol Compliance

ElixIRCd follows the core IRC RFCs closely:

• RFC 1459 — Internet Relay Chat Protocol (core protocol)
• RFC 2810 — IRC Architecture
• RFC 2811 — IRC Channel Management
• RFC 2812 — IRC Client Protocol
• RFC 2813 — IRC Server Protocol (partial; S2S not implemented)
• RFC 7194 — Default Port for IRC via TLS/SSL (port 6697)

Technology Stack

Component	Technology
Language	Elixir 1.19+
Runtime	Erlang/OTP (BEAM VM)
Database	Mnesia (in-memory ETS tables via memento library)
TCP/TLS Server	ThousandIsland
WebSocket Server	Bandit
Password hashing	Argon2id (argon2_elixir)
Rate limiting	Hammer (token bucket algorithm)
Email delivery	Bamboo + Bamboo MUA (SMTP)

License

ElixIRCd is licensed under the AGPL-3.0 (GNU Affero General Public License v3). This means any modifications you deploy over a network must also be open-sourced under AGPL.