Accessing Kerberos NFS version 4 (not 2, 3) via /net automounter with kinit only (no /etc/krb5.conf access)

[Wang Shouhua]

Lets recap:

1. Requirements:
- Linux or Solaris
- NFS automounter set up at /net
- Kerberos5 configured for realm EXAMPLE2.COM, rpc.gssd running
- A NFS server (version 4 only) nfsserver.most.gov.cn exists in the
realm MOST.GOV.CN, with a subdir of test3

2. Goal:
A user provides his password to obtain a ticket for user2 at MOST.GOV.CN
(optionally nfs at MOST.GOV.CN, if this is a requirement to do a mount),
and is then able to cd into /net/nfsserver.most.gov.cn/test3, and do a
successful ls -al there

Is that possible?

Wang

---------- Forwarded message ----------
From: Will Fiveash <will.fiveash at oracle.com>
Date: 11 April 2014 22:14
Subject: Re: Accessing Kerberos NFS via /net automounter with kinit
only (no /etc/krb5.conf access)
To: Wang Shouhua <shouhuaw at gmail.com>
Cc: Kerberos at mit.edu


On Tue, Apr 01, 2014 at 06:00:45PM +0200, Wang Shouhua wrote:
> I am on Solaris 10U4 - can I access a NFS filesystem with (mandatory)
> krb5p authentication via the Solaris /net automounter with kinit only,
> without having r/w access to /etc/krb5.conf access)?

You'll need to have Solaris krb configured which stores its config in
/etc/krb5 not /etc as is the MIT default.  You'll also need read access
to /etc/krb5/krb5.conf and have the system properly configured to do NFS
with krb in general (read the Solaris 10 online docs).

Beyond that, whether a user kinit'ing is enough depends on which version
of NFS you are using.  On the client side NFSv3 sec=krb5p shares will
automount if the user triggering the mount has a krb cred in their
ccache (klist will show that) and does not require any keys in the
system keytab nor does it require root to have a krb cred in general.

NFSv4 on the other hand does require that the root on the NFS client
system have a krb cred in its ccache.  This can be done either by
running kinit as root or having at least one set of keys for either the
root/<host> or host/<host> service princ in the system keytab which will
be automatically used to acquire a krb cred for root.

On the client system "nfsstat -m" will show what version of NFS is being
used.

--
Will Fiveash
Oracle Solaris Software Engineer


-- 
Wang Shouhua - shouhuaw at gmail.com
ÖлªÈËÃñ¹²ºÍ¹ú¿Æѧ¼¼Êõ²¿ - HTTP://WWW.MOST.GOV.CN