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From: jerry@oliveb.UUCP (Jerry Aguirre)
Newsgroups: net.unix-wizards
Subject: Symbolic user names and RFS
Message-ID: <674@oliveb.UUCP>
Date: Thu, 13-Feb-86 18:31:39 EST
Article-I.D.: oliveb.674
Posted: Thu Feb 13 18:31:39 1986
Date-Received: Sat, 15-Feb-86 03:07:31 EST
Reply-To: jerry@oliveb.UUCP (Jerry Aguirre)
Organization: Olivetti ATC; Cupertino, Ca
Lines: 45
Keywords: RFS chown

I installed the remote file system (RFS) distributed over the net and
found a big gotcha that other users should be aware of.

If you "ls" files on a remote file system then the symbolic owner and
group displayed will not be correct.  Similarly if you "chown" using a
symbolic name that will probably not do what you want it to.

This follows as a natural result of the fact that these programs are
using the password file of the client to translate between symbolic and
numeric user IDs (UID).  Unless you have maintained the same UID numbers
on the server systems then the translation will be incorrect.

Our systems all share UIDs for root, man, news, uucp, etc. but a normal
user with accounts on all systems will have little chance of having the
same UID.  The most graffic illistration of this is to "ls -l" the
remote file system containing the users' login directories.  Normally
the owner and directory name are the same.  Under RFS there is a
arbitrary substitution of client names for the server's file owners.

Even worse is to see this and decide to "chown" the files back to what
they should be.  The files will now appear correct when listed from the
client but wrong when listed locally on the server.

If you need to chown a remote file then grep the user from the REMOTE
password file and use a numeric chown.  Or just use rsh to run the
chown command.

Sollutions:

  * One sollution is to have the same password file on all hosts.  This
    means a massive chown of existing users as well as an ongoing
    effort to maintain compatability.

  * It is unreasonable (and contrary to the goal of RFS) to modify ls,
    chown, find, etc. to deal with the remote UIDs.

  * A better alternative would be for the server to map U/GIDs for stat,
    chown, etc.  It has both password files available for translating
    the IDs.  The only detail is how to handle names that exist on the
    server but not on the client.

Anybody know how this is handled on other networked file systems?

					Jerry Aguirre @ Olivetti ATC
{hplabs|fortune|idi|ihnp4|tolerant|allegra|glacier|olhqma}!oliveb!jerry