RFC 2055 (rfc2055) - Page 3 of 10

WebNFS Server Specification

RFC 2055              WebNFS Server Specification           October 1996


   constant port assignment, 2049, for both UDP and TCP.

   To avoid the overhead of contacting the server's portmap service, and
   to facilitate transit through packet filtering firewalls, WebNFS
   clients optimistically assume that WebNFS servers register on port
   2049.  Most NFS servers use this port assignment already, so this
   client optimism is well justified.

   A WebNFS server must register on UDP port 2049 and TCP port 2049 if
   TCP is supported.

4. Server Port Monitoring

   Some NFS servers accept requests only from reserved UDP or TCP ports,
   i.e. port numbers below 1024.  These "privileged" ports are available
   only to Unix processes with superuser permissions.  Requests that do
   not originate from the range of reserved ports are rejected.  This an
   optimistic way of preventing direct access to the server from user
   processes that may attempt to spoof AUTH_UNIX RPC credentials.

   Since WebNFS clients are not required to use reserved ports, a WebNFS
   server must not check the originating port for requests to
   filesystems made available to WebNFS clients.

5. Public Filehandle

   The public filehandle is an NFS file handle with a reserved value and
   special semantics that allow an initial filehandle to be obtained.  A
   WebNFS client can use the public filehandle as an initial filehandle
   without using the MOUNT protocol.  Since NFS version 2 and version 3
   have different filehandle formats, the public filehandle is defined
   differently for each.

   The public filehandle is a zero filehandle.  For NFS version 2 this
   is a filehandle with 32 zero octets.  A version 3 public filehandle
   has zero length.

5.1 Version 2 Public Filehandle

   A version 2 filehandle is defined in RFC 1094 as an opaque value
   occupying 32 octets.  A version 2 public filehandle has a zero in
   each octet, i.e. all zeros.

    1                                                             32
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




Callaghan                    Informational