Limitation on number of /etc/group memberships?

[dupuy at cs.columbia.edu]

> It seems that when a user is a member of 9 or more groups, things get very
> wierd at login time.  The user logs in and the following messages appear: 
> 
> RPC error: Invalid authentication
> /home/user-id: not owner

This is a bug in Sun NFS support in 4.0.  Under SunOS 3.x and 4.2 BSD, the
group limit was 8.  SunOS 4.0 and 4.3 BSD raise the group limit to 16, but
the NFS protocol had only 8 slots for group membership information when
using Unix authentication.

SunOS 4.0 will put more than 8 group entries into the authunix structure,
which causes problems on machines expecting the old 8 slot entries.  It
may even cause problems for other 4.0 machines, I don't remember.  Ways to
work around this might be:

	1) reduce the number of groups the user is in to 8
	2) make the user a member of a different set of 8 on different machines
	   (this can be done with entries in /etc/groups even if you use YP,
	    and can allow the user to be in as many groups as they want, though
	    they have to log in to ceratin machines to be in them)
	3) use secure NFS, since authdes structures have no group info
	   (this would work if standard NFS between 4.0 machines is broken, but
	    isn't much help with 3.x or other OS's, since they don't have
	    secure NFS)