*BSD News Article 53120


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From: Andrew Gordon <andrew.gordon@net-tel.co.uk>
Subject: Re: 2.0.5 -> NFS -> Linux: some files inaccessable
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jshiffle@netcom.com (John Shifflett) wrote:
>When I mount 2.0.5 partitions on a Linux machine (using NFS), files
>and directories owned by root are not readable. Since my DAT drive is
>on the Linux computer, I need _everything_ available through NFS so I
>can make tape backups. (Yes, I'm mounting and attempting to read as
>root). Is there something special I need to do to get this happening?

This is normal NFS behaviour, in order to retain a vestige of security
in the normal NFS case where the protocol is totally insecure.
Since the protocol amounts to you simply saying who you are and the
server trusting the answer (ignoring kerberos-based NFS authentication),
it is regarded as simply too risky to trust arbitrary users who
claim to be root.

>(Other _Linux_ computers mounted via NFS don't have this limitation.)

Linux is abnormal in this respect.

The usual solution to the problem is to construct the tape archive
on the machine where the disks are, and access the tape drive remotely
- either using somthing sophisticated, or using 'rmt', or simply using 
somthing like:

diskful_machine%  tar cf - . | rsh tape_machine -l userid dd 
of=/dev/tape