FS2NetD
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 Parralax Online service. It was created in 2003 by Derek "Kazan" Meek, a member of the SCP dev team and also the author of the PCS and PCS2 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.
External Links
PXO website (discontinued)