NFS services
NFS provides its services through a client-server relationship.
The computers that make their file systems, or directories, and other resources available for remote access are called servers. The act of making file systems available is called exporting. The computers and their processes that use server resources are considered clients. After a client mounts a file system that a server exports, the client can access the individual server files (access to exported directories can be restricted to specific clients).
The major services provided by NFS are:
| Service | Description |
|---|---|
| Mount service | Mounts from the /usr/sbin/rpc.mountd daemon on the server and the /usr/sbin/mount command on the client. This service is only available on NFS version 2 and version 3. |
| Remote File access | Accesses from the /usr/sbin/nfsd daemon on the server and the /usr/sbin/biod daemon on the client. |
| Remote execution service | Executes from the /usr/sbin/rpc.rexd daemon on the server and the /usr/bin/on command on the client. |
| Remote System Statistics service | Compiles from the /usr/sbin/rpc.rstatd daemon on the server and the /usr/bin/rup command on the client. |
| Remote User Listing service | Lists from the /usr/lib/netsvc/rusers/rpc.rusersd daemon on the server and the /usr/bin/rusers command on the client. |
| Boot Parameters service | Provides startup parameters to Sun Operating System diskless clients from the /usr/sbin/rpc.bootparamd daemon on the server. |
| Remote Wall service | Protects from the /usr/lib/netsvc/rwall/rpc.rwalld daemon on the server and the /usr/sbin/rwall command on the client. |
| Spray service | Sends a one-way stream of Remote Procedure Call (RPC) packets from the /usr/lib/netsvc/spray/rpc.sprayd daemon on the server and the /usr/sbin/spray command on the client. |
| PC authentication service | Provides a user authentication service for PC-NFS from the /usr/sbin/rpc.pcnfsd daemon on the server. |
| Enhanced security service | Provides access on both the client and server to more advanced security services, such as Kerberos 5. The /usr/sbin/gssd daemon provides NFS with access to security services provided by the Network Authentication Service. The Network Authentication Service and the Cryptographic Library filesets (krb5.client.rte, krb5.server.rte, and modcrypt.base) must be installed. These filesets can be installed from the AIX® Expansion Pack. |
| Identity translation service | Performs translation between security principals, NFS version 4 identity strings, and their corresponding numeric system IDs. In addition, mapping of identity information from foreign NFS version 4 domains is provided. These services are provided by the /usr/sbin/nfsrgyd daemon. |
NFS version 2 and 3 servers are stateless, meaning that the server does not retain any transaction information about its clients. A single NFS transaction corresponds to a single, complete file operation. NFS requires that the client remember any information needed for later NFS use.
An NFS version 4 server is stateful because of the file open and file locking operations defined in the NFS version 4 protocol.