[TUHS] RFS was: Re: UNIX of choice these days?

Don Hopkins don at DonHopkins.com
Sat Sep 30 04:40:41 AEST 2017


On 29 Sep 2017, at 17:22, George Ross <gdmr at inf.ed.ac.uk> wrote:

> I dunno why all the hating on diskless.  They actually work, I used the
> heck out of them.

The issue we (initially) had with Suns wasn't the stateful/stateless debate,
or indeed that they were discless.  It was that horrible "UNIX
authentication" that NFS used.

When I was a summer intern at Sun in ’87, it was common knowledge among the staff that anyone could find out what hosts an NFS file server trusted by using tftp, which was installed by default, and anonymously grabbing /etc/exports (or guessing hostnames if you can’t get the definitive list). 

Then you just go “hostname trusted-hostname ; mount -t nfs sever:/dir ; hostname original-hostname” to mount that file system.

That’s right: the NFS server TRUSTED the NFS client to tell it what it felt like its hostname should be at that particular instant in time!!! If the name the client sent in the parameter to the mount rpc call was listed in /etc/exports, then the server returned a file handle to the client for it to use from then on, even after changing its hostname back! 

I was able to nfs-mount a directory on one of cs.cmu.edu's servers from sun.com’s network with no problem. Ron may remember me warning him about that! 
 
-Don



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