From FreeSpace Wiki
FS2NetD is an online stat tracker and master server for FreeSpace Open multiplayer games, serving as a replacement to the now-defunct Parallax Online service. It was created in 2003 by Derek "Kazan" Meek, a member of the Source Code Project development team and also the author of the POF Constructor Suite and POF Constructor Suite 2 model conversion tools, and has gone through multiple upgrades since then.
The service is currently hosted by Game Warden.
For information on how to connect to and use FS2NetD, see the Multiplayer Getting Started Guide.
PXO website (discontinued)