RFC 2055 (rfc2055) - Page 3 of 10
WebNFS Server Specification
Alternative Format: Original Text Document
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|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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