Is GLUT also an open source. Is it free to distribute, etc…

GLUT is copyrighted by Mark Kilgard but is free to distribute. The sources is also available so I guess you could call it open source whatever that means. If you want to dirtibute a changed version is it best to call it something else than GLUT.

Can anyone tell me how to get the latest header and library files? the link on is a dud (points to 5y.o. files) and I cannot find them anywhere else