mountd

Mountd is a daemon used by traditional Network File System (NFS) servers to manage the mount protocol and exported file systems. It handles MOUNT requests from NFS clients and provides the list of exports, enabling remote mounting of a file system shared by the server. The daemon determines which file systems are available for mounting by reading the server’s export configuration.

In typical deployments, mountd runs as rpc.mountd (or simply mountd) and communicates with clients through the RPC framework provided by rpcbind or portmap. It operates alongside other NFS services that serve file data, and is often started automatically at boot on Unix-like systems that ship with NFS.

Export configurations control access and behavior. The server reads a configuration file (commonly /etc/exports) to decide which file systems are shared and which clients may mount them. Export options specify permissions and handling, such as read-only or read-write access, root squashing, and related behaviors. These options are part of the NFS server’s export policy and influence how clients are allowed to mount and access the exports.

With the introduction of NFSv4, the mounting process has been simplified and mounted via a different mechanism, reducing mountd’s role for v4, though many systems preserve the legacy mount protocol for v2/v3 interoperability.

Overall, mountd remains a foundational component of traditional NFS deployments, coordinating mount requests and export visibility to clients and enforcing export policies defined by the administrator.