RPC and NFS

RPC and NFS

Network File System (NFS)

NFS, defined by RFC 1094, is a method for client systems to use a filesystem on a remote host computer. NFS uses the UDP protocol and is supported by RPC.

Remote Procedure Call (RPC)

RPC, defined by RFC 1057, is a set of function calls used by a client program to call functions in a remote server program. The port mapper program is the program used to keep track of which ports programs supporting RPC functions use. The port mappers port is 111. In Redhat Linux the portmapper daemon is started in the /etc/rc.d/init.d/portmap and the daemon program is called "portmap".

The rpcinfo command

The command "rpcinfo -p" will show the port numbers that are assigned to the RPC services.

   program vers proto   port

    100000    2   tcp    111  portmapper

    100000    2   udp    111  portmapper

    100011    1   udp    747  rquotad

    100011    2   udp    747  rquotad

    100005    1   udp    757  mountd

    100005    1   tcp    759  mountd

    100005    2   udp    762  mountd

    100005    2   tcp    764  mountd

    100003    2   udp   2049  nfs

Services that may be listed include:

• rquotad - Enforces the set quotas for remote mounted NFS systems.
• mountd - Performs the requested mounts.
• nfs - Handles the user interface to the kernel module that performs NFS.

NFS related services in Linux include:

• amd - Runs the automount daemon for automatic remote filesystem mounting such as nfs. It is especially worthwhile for working with removeable media such as floppies or CD ROM disks.
• autofs - This is the startup, stop, and status script for the automount program used to configure mount points for automatic mounting of file systems.
• nfs - Provides Network File System server services.
• netfs - Mounts and unmounts Network Fils System (NFS), Windows (SMB), and Netware (NCP) file systems. The mount command is used to perform this operation and no daemon is run in the background.

The /etc/exports file is used to configure exported filesystems