UID mapping for NFS

[Tom H]

> I have a few systems on site which have common users installed with "wrong" UID
> values from the rest of the machines, and particularly those installed from a
> "live" CD which created one or more odd IDs when "install to disk" was used.

> I remember using "UID mapping tables" to cause an NFS access from "joe" on the
> client to use the UID of "joe" in the request sent to the NFS server. I can't
> recall if that was in Linux, or some other OS, I was supporting Xenix, AIX,
> Solaris, SunOS, and HP-UX at the time. Oh, and Dell's brief jump into SV5r4 on PC.

> If this is supported it would be miles easier than shuffling the UIDs on the
> clients, obviously. I though there was a mount option but I don't see it, and
> it's been a good decade since I did this and I can't remember details.

> I thought I was remembering the map_static option, but it is not recognized in
> exports, not are map_daemon or no_map_identity.
> (see: http://ftp.sunet.se/LDP/LDP/nag2/x-087-2-nfs.exports.html)

> What do I miss, the doc says it's there, the software disagrees.

In the Debian-Ubuntu world, there is nfs-user-server package (as
opposed to the "usual" nfs-kernel-server) package where the map_*
options work (map_daemon when you install ugidd), so that is probably
the origin. Even CentOS 5.4 no longer has a similar man page for
exports.

nfsv4's idmapd maps ids but I don't think that, even though the
credentials that are exchanged are "user at domain", AFAIK it will only
map the usernames on the client and the server if their uids match.