Lemoniscate

What is Lemoniscate?

Lemoniscate is a ground-up C and Objective-C implementation of the Hotline server, designed for Mac OS X 10.4 Tiger and 10.5 Leopard on PowerPC architecture. Based on the Mobius server’s source code, it was rewritten from scratch for PowerPC compatibility.

It brings the complete Hotline server features to older PowerPC-based Mac. It supports chat, instant messaging, file sharing, news boards, user management with 41 permission bits, Bonjour/mDNS discovery, and a native GUI admin application for server management.

Because it is written in C, Lemoniscate is extremely lightweight and keeps RAM and CPU overhead to a minimum, which makes it a good fit for older hardware and small always-on servers.

Lemoniscate has full Hotline 1.9 protocol support, plus newer quality-of-life features like HOPE secure logins and built-in TLS certificate generation. In plain terms, that means better compatibility with Hotline clients and better privacy for logins and connections. TLS is the same kind of encryption used to protect normal websites, so it helps keep passwords and server traffic from being sent around in the clear.

The original target is still PowerPC Mac OS X, but Lemoniscate now also has released Linux builds available for download, with support for modern macOS 10.11 through current releases, and the modern codebase can be built with Docker.

Architecture

Lemoniscate is built in two parts: the server itself is written in C, and the admin GUI is a native macOS application written in Objective-C. The GUI launches and manages the server behind the scenes, so you get a point-and-click interface for everything. This also makes the code more portable and easier to maintain, and hopefully more forkable for tinkerers.

It supports the same feature set as Mobius, but isn't a direct port due to the differences in the Go vs C architecture. Expect features down the road that go beyond what Mobius offers with new features, tailored specifically for the PowerPC platform and its constraints while still being compatible with the Hotline protocol.

For nerds: te Hotline protocol is natively big-endian, and so is PowerPC. That means the protocol maps directly to the hardware’s byte order with no translation overhead.

Why the name?

The name references the lemniscate (the infinity symbol ∞), which is topologically related to the Möbius strip. And it’s a lemon. Hence, Lemoniscate.

Download

Lemoniscate weighs in at around 550KB and uses under 25MB of RAM. Compatible with Hotline Navigator and classic Hotline clients.

Linux releases are now available to download as well, and Docker can be used to help build the modern cross-platform codebase.

Fun-fact: 100k of the file size is the icon image.

Lemoniscate is open source and free to use.