Re: [PLUG] portmapper and NFS.

[Stephen Gran <steve@lobefin.net>]

On Sat, Jul 07, 2007 at 10:02:28AM -0400, Mag Gam said:
> I am trying to understand the technical details why we need portmapper(RPC)
> for NFS.
> I have been reading,  "http://en.wikipedia.org/wiki/Portmap";
> 
> Does anyone know exactly what this service does, and the importance of it
> for NFS? I know NFSV4 does not need Portmapper, so why does NFS Version 3
> and 2 need it?

NFSv3 services by default does not listen on a regularly assigned port -
they ask the OS at startup for a random port, and then listen on it.
portmapper exists to translate RPC call requests into port numbers.
This way, when one machine needs to know how to do an RPC call to, fo
instance, figure out the files in a directory, the application talks to
portmapper, which figures out what port the relevant service is on, and
then network traffic can happen.  It does seem a bit arcane to me as
well.
-- 
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|  Stephen Gran                  | If it were not for the presents, an     |
|  steve@lobefin.net             | elopement would be preferable.   --     |
|  http://www.lobefin.net/~steve | George Ade, "Forty Modern Fables"       |
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