[rhelv6-list] NFS ID map?

[Joshua Baker-LePain]

On Tue, 22 Oct 2013 at 12:35pm, Chris Adams wrote

> Once upon a time, Joshua Baker-LePain <jlb17 at duke.edu> said:
>> Are you using Kerberos with NFSv4?  If not, then the numeric UIDs
>> and GIDs still must match.  idmapd *will* map usernames for display
>> purposes (i.e. what 'ls -l' sees), but the numeric IDs are still
>> used for permissions. Clear as mud, ain't it?
>
> Oh, that may be why I've always been confused by the ID mapping (and
> avoided it).  Now, I'm not using Kerberos, so it sounds like the ID
> mapping won't actually help me with my problem.  <sigh>
>
> What's the point of ID mapping if it only maps them in some places?
> That's terribly confusing.

Yes.  Yes it is.

> stat() sees the numeric ID mapped (and chown()), but I guess open()
> permission checks don't?

This (rather old) thread explains it better than I can:

http://thread.gmane.org/gmane.linux.nfsv4/7103/focus=7105

-- 
Joshua Baker-LePain
QB3 Shared Cluster Sysadmin
UCSF