NIS/NFS question

[Ryan Golhar]

Hi Wayne,

We have actually done exactly what you are doing.  We've since switched
to LDAP to encrypt passwords sent over the wire.  But the problem you
are referring to is the same we have now.  I wouldn't have enough
thought of it if you didn't mention it.  

I believe you can use iptables with --mac-source to control access by
MAC address.  

Right now, we only allow our linux machines to nfs mount /home on the
server by iptables:

-A ADDRESS-FILTER -s xxx.xxx.xxx.xxx -j ACCEPT

Making it 

-A ADDRESS-FILTER -s xxx.xxx.xxx.xxx --mac-source XX:XX:XX:XX:XX:XX -j
ACCEPT
 
Should do the trick.  Let me know what happens and what you decide to
do...

Ryan



-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of Wayne Pinette
Sent: Wednesday, June 29, 2005 5:37 PM
To: redhat-list at redhat.com
Subject: NIS/NFS question


I have a question regarding NIS and was wondering if anyone had any
ideas.

We are creating a Linux workstation lab for students.  We have a central
linux box which teh students can ssh into from home. The lab is a place
where they can log in and work on their work.  We are using NIS to
authenticate the workstations and we are nfs mounting the /home
directory.  This is all pretty standard and make sense.  Here is the
problem : 

If a student walks into the lab with their laptop running their
favourite linux to which they have root access, unplugs a workstation,
plugs in their laptop, hardcodes the worksation's ip, sets ups his
laptop to nis authenticate and nfs share just like the workstation, logs
in as root, he can now su to any student id on the system. 
Although I quash root on the nfs share, it does not stop this student
from getting access to any other students (or instructors) material on
the server.  Although my nis server only trusts a small list of 
ip addresses, it's trust is still only based on ip.  Is there a way to
add some sort of certificate trust to nis or some other mechanism to
check against before nis will trust a machine on it network other than
just ip?

Wayner

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