What is ferrixd?

ferrixd (Ferrous IRC Daemon) is an RFC-conformant, IRCv3-complete IRC server written from scratch in Rust. It exists because IRC — the oldest federated chat protocol still in daily use — deserved a server built with modern engineering standards: memory safety, attack resistance, honest persistence, and high connection density.

The name is a chemistry joke that got out of hand: Fe, element 26, is iron; Rust is what iron becomes; ferrixd is an IRC daemon written in Rust. The logo is iron's periodic-table tile.

What you get

A single static binary that is:

• A complete IRC server. Registration, channels, modes, topics, WHO/WHOIS, MOTD, LUSERS, MONITOR, LIST — the full classic surface, with consistent ascii or rfc1459 case mapping.
• An IRCv3 server. 29 capabilities, including server-time, message-tags, batch, echo-message, labeled-response, standard-replies, draft/chathistory, draft/multiline, and draft/metadata-2. Capabilities are implemented against the spec text, not against what other servers happen to do. See the capability reference.
• Its own services. Accounts, SASL (PLAIN, EXTERNAL, SCRAM-SHA-256), account self-registration, and channel registration are built into the daemon — there is no bolted-on NickServ/ChanServ pseudo-server to keep in sync or crash independently.
• A federation node. Servers link over mutual TLS with pinned certificate fingerprints and form a multi-hop mesh: cross-server channels, messages, WHOIS, netsplit cleanup, and deterministic nick-collision resolution — no synchronized clocks required. See Federation.
• Extensible, safely. Moderation hooks can be written as sandboxed WASM plugins executed under a fuel budget — a buggy or malicious plugin traps instead of hanging the server. See WASM Plugins.
• Operable. Prometheus metrics, structured tracing, REHASH hot-reload, a config validator (ferrixd check), and built-in helpers for certificates and password hashes. See Observability.

What makes it different

Memory safety is not negotiable

unsafe_code = "forbid" applies to the entire workspace — not "minimal unsafe", zero. The wire parser, the security-critical hot path, lives in its own dependency-light crate (ferrix-protocol) so it can be fuzzed and audited in isolation. It parses without copying, never panics on hostile input, and CI promotes panic!/unwrap/expect in the data path to build errors.

TLS is the transport, not an option

The primary listener is TLS. A plaintext listener exists for local testing only: binding it to a non-loopback address is a configuration error unless you explicitly set allow_plain_nonlocal = true. Passwords are hashed with Argon2id and verified in constant time; hosts can be cloaked with an HMAC so they are unforgeable.

Designed for hostile networks

Every resource a client can consume is bounded: outbound queues (SendQ), inbound command rate (token bucket), connections per IP, registration time, TLS handshake time, history memory, list-mode entries. Exceeding a bound has a defined, documented consequence — usually disconnection with a reason that shows up in the metrics.

Density as a feature

One async task per connection — not one thread — over a fixed worker pool and sharded shared state. Load-tested to ~100,000 concurrent connections on an 8-core host at ~1.38 GB RSS (~13.8 KB per connection), scaling linearly. The methodology and generator live in the repository's loadtest/ directory.

What it is not

• Not a TS6/legacy-protocol server. The S2S protocol is modern and ferrixd-native (spec here). Linking to charybdis/solanum works through the dedicated TS6 bridge, which translates at the network edge — the native protocol stays legacy-free.
• Not a hosted service. ferrixd is software you run. It has no accounts web portal, no built-in web client.
• Not finished deciding what IRC should be. Draft capabilities (draft/…) are implemented as drafts and will track the specs as they stabilize.

Where to go next

You want to…	Read
See it run in 60 seconds	Quick Start
Install it properly	Installation
Configure a real server	Configuration
Link two servers	Federation
Look up an exact flag, cap, or limit	Reference
Understand how it's built	Architecture