Many Sun remote programs operate on behalf of particular Unix users and require the access rights associated with that user. Unix-flavor SunRPC credentials make this possible. Essentially, a Unix-flavor credentials object consists of a Unix uid ("user id", a CARDINAL) and a list of up to 10 Unix gid's ("group id's", also CARDINALs). You can think of these numbers as capabilities. They are host-specific, but our far-sighted system administrators have arranged for all Suns to use the same space of uid's and gid's, and to store them in the Yellow Pages data base.

There are no passwords or encryption or other such frills. The basic philosophy here is that all kernels are trustworthy, so for example if a server receives a remote procedure call claiming to be from John Smith and requesting that a file be deleted, it takes it on faith that the call really is from John Smith and deletes the file if John Smith is entitled to do so.

This is clearly bogus, and Sun has plans to fix it eventually. For now, we just make every effort to ensure that Cedar kernels are trustworthy in the above sense. That is, we need a reliable way to map Cedar (Grapevine or XNS) credentials to legitimate Unix uid/gid sets.