MOUNT

The MOUNT protocol is used in NFS version 2 and 3 to find the initial filehandle for the mountpoint.

The protocol is no longer used in NFS version 4 since this functionality has been incorporated into the NFS protocol itself.
Since MOUNT is not using a fixed standard port it is difficult to use MOUNT and thus NFS through a firewall. Some vendors such as SUN do however implement extra features to the NFS protocol to allow to eliminate the need of the MOUNT protocol (mount option public). This allows a client to mount an NFS share through a firewall but does not address the issues with the NLM lock management protocol nor the NSM status monitoring protocols making this workaround only useable for read-only filesystems.

History

The MOUNT protocol is a support protocol for versions 2 and 3 of NFS. (It is also used for version 1 of NFS but no one I know of have ever seen such captures).
Until today there has been 3 different versions of the MOUNT protocol, version 1, 2 and 3. These versions are virtually identical as far as normal unix NFS servers and clients are concerned and only differ by version 2 and version 3 removing some of the procedures that are never used anyway.

Protocol dependencies

Wireshark

The MOUNT dissector is fully functional. The Service Response Time statistics feature in both Wireshark and TShark can calculate response time statistics for this protocol.

Preference Settings

There are no preference settings for the MOUNT protocol.

Example capture file

Display Filter

A complete list of MOUNT display filter fields can be found in the display filter reference

Capture Filter

You cannot directly filter on the MOUNT protocol while capturing. Since MOUNT does not use a standard port you can not capture on a specific port either.

Tools

On Un*xes that include RPC support, the following tools are usually part of the OS:

Discussion

MOUNT (last edited 2008-04-12 17:50:39 by localhost)