Crownlink is a networking provider that is compatible with blizzard's storm-based games from the 90s. It's specifically developed with the starcraft overhaul Cosmonarchy in mind, but should work for other blizzard games from the era.
Download the latest CrownLink.snp from releases and drop it in your game directory next to the default ones. For Cosmonarchy this is typically C:\Cosmonarchy\Starcraft\. You should have a new entry in the multiplayer menu show up.
Please make sure you have an up to date version of microsoft visual c++ redistributable x86 installed: vc_redist.x86.exe
(comes from this site: learn.microsoft.com)
You may see games in the multiplayer menu tagged with [Relayed] in the game name. This means direct peer to peer communication couldn't be established and a TURN relay server is in use. Performance may not be as good as a direct peer to peer connection.
This version of the code has some files from BWAPI and is therefore licensed GPLv3. (TODO: update licenses file)