Is rpcbind needed for an NFS client?

Question

I understand that rpcbind runs on NFS servers to respond to port-mapping requests from clients.

Is the rpcbind daemon needed on an NFS client?

I'm surprised that it is so difficult to find a definitive answer to this question. That might be because there's no reason to suspect that it is required.

The reason I'm asking is because I found that rpcbind is running on a number of Debian servers that are not NFS servers. And surprisingly, the nfs-common package directly depends on rpcbind, even though:

Use this package on any machine that uses NFS, either as client or server.

Related Serverfault questions:

• NFS client firewall settings and rpcbind

  I don't understand why nfs-common depends on rpcbind if it works without it. Am I missing anything ? Maybe rpcbind is needed for file locking or nfs stats.

• Can rpcbind packagebe removed in debian wheezy, installed by default?

  Yes, you can safely remove rpcbind if you don't plan on using NFS on your server.

• NFS client firewall settings and rpcbind

  apt-cache depends nfs-common gives rpcbind as a direct dependency.

Answer 1

The NFS client uses rpcbind service on server to discover the port number used by nfsd.

More over, for clients of nfs v2 and v3, an additional rpc-statd service is used to manage locks. As rpc-statd runs on the client, a rpcbind should run on the client to let nfs servers to discover on which port rpc-statd listens.

Thus, for client that uses nfs v4, the rpcbind, rpc-statd and rpc-statd-notify services can be disabled. This can required modifying some .service files.

IOW - The rpcbind service is needed by nfs clients that use v2 and v3, as it required for file locking, and can be disabled for nfs v4 clients, as locking is a part of the NFSv4.0 protocol.