This DLL is not, and will not be ported to Linux. A full Quake2 for Linux was released in January 1998, with linuxquake2-3.10. Note that all Linux ports, including the Mesa based ones, are not officially supported by id Software. A revision of Mesa and the Mesa-based Linux glQuake is in preparation. Here is an excerpt, as of January 7th, 1998.
Dedicated server requires no special permissions.
X11 has some garbage on the screen when 'loading'. This is normal in 16bit color mode. It would be very slow in any case. Some people are experiencing crashes with the GL renderer. Older versions of libMesa don't work properly.