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From: nowicki@SUN.COM (Bill Nowicki)
Newsgroups: mod.protocols.tcp-ip
Subject: More NFS discussion
Message-ID: <8612222136.AA06270@rose.sun.com>
Date: Mon, 22-Dec-86 16:36:01 EST
Article-I.D.: rose.8612222136.AA06270
Posted: Mon Dec 22 16:36:01 1986
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Development of real commercial network protocols is full of
compromises, so it is not too suprising that some people think NFS is
too Unix-like, while others think it is not Unix-like enough.
Commercial MS-DOS and VMS products were demonstrated in February 1986,
as well as many different Unix dialects, from PCs to a Cray-2.

Let me try to correct some misconceptions:

	..., NFS has no security or authentication.

Authentication is done at the RPC level in a very open-ended
manner.  The default in the first implementation was to trust UIDs,
since that is all that Unix provides.  A scheme based on public-key
encription has been discussed in papers (Goldberg and Taylor, Usenix
conference 1985).

	... it is assumed that there is a GLOBAL /etc/passwd file

No, your implementation is free to have a simple table that maps these
UIDs into whatever identifier that you use on your system.  We found it
easier to administer by keeping a unique number over as large a domain
as possible.  At some point you may have to translate between numbers
that make sense in your domain, but having N x M translation tables is
not practical to maintain.

	NFS uses very large UDP packets ...

No, details of transport such as packet size are determined by both
the client and server implementations.  Slow machines like PCs use
small transfer sizes, while faster machines such as Sun-3s take
advantage of larger buffer sizes when available.

	So if a complete RPC and NFS can be fit into 64K, why is PC-NFS
	client only?

Although I am not a PC user (luckily I have a Sun-3/75) my
understanding is that MS-DOS (and the Mac, for that matter) can only
run one program at a time.  Therefore if you ran a server, then you
could not run any other programs on that PC. We find in actual practice
that people only put on floppies the files that they DO NOT want other
people to get at - shared files can go on an NFS file system, and you
use MS-DOS "COPY" commands to copy from one PC to another.

Remember that Sun is an active member of the Corporation for Open
Systems, and has ISO and FTAM (second DP version) products.  NFS only
makes many of the file-sharing problems visible - we need to continue
research in this area.  On the other hand, people with inter-operability
questions should come to Uniforum in January 1987 and see it work
for themselves.

	-- Bill Nowicki
	   Sun Microsystems

Above are personal opinions only, not official Sun positions.