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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!bu-cs!purdue!decwrl!decvax!tektronix!ozvax!tekcsc!jeff
From: jeff@tekcsc.MKT.TEK.COM (Jeff Beadles)
Newsgroups: comp.unix.questions,comp.unix.wizards
Subject: Re: Nfs -- root privs
Message-ID: <162@tekcsc.MKT.TEK.COM>
Date: 1 Feb 89 10:46:16 GMT
References: <695@blake.acs.washington.edu>
Reply-To: jeff@tekcsc.MKT.TEK.COM (Jeff Beadles)
Distribution: usa
Organization: Tektronix, Inc.  Wilsonville, Or.
Lines: 47

In article <695@blake.acs.washington.edu> mtsu@blake.UUCP (Montana State) writes:
>
>
>I have 4 mVAXen hooked together, and I'm using a lot of NFS serving to
>provicde home directories and all that crap.  I'm running Ultrix 2.3
>on all nodes, I'm not running YP.  What I want to do is to be able to sit
>as root on caesar, and modify files on the other machines.  This used to
>work uder Ultrix 2.0, there was a procedure to change the value of the
>kernel variable nobody to 0 rather than -2.  It don't seem to work under 2.3
>...  I tried changing the nobody passwd entry to 0:0 for UID and GID, and that
>didn't work either.  Any suggestions??
>
>Replies to icsu6000@caesar.cs.montana.edu or utah-gr!mts-cs!icsu6000 if these
>questions are too basic.


Well, it's a little more involved than that.  Here's how to do it. 
(First, a disclaimer...)

	TEKTRONIX DOES NOT SUPPORT THIS MODIFICATION.

===============================================================================

Unsupported modification to change kernel's idea of who root should be when
traversing an NFS mountpoint.  This is a security problem, if implimented.


ON SERVER MACHINE
--------------------------------------------------------
cd /				# move to root directory

cp vmunix vmunix.old		# make copy of vmunix

adb -w /vmnix /dev/kmem		# invoking adb	

nobody/D			# should say -2

nobody/W 0			# should say _nobody: 0xfffffffe = 0x0

nobody/D			# should say 0

$w				# write

$q				#quit

Then, reboot with the new kernel.
================================================================================