CentOS Linux Server Guide

Network File Server (NFS)

We are going to discuss the following topics in this module.

Setup NFS server
Mounting Network File Systems (Manual) - NFS Client
Mounting Network File Systems (Automount) - NFS Client
Unmouting File System - NFS Client
NFS Logs - NFS Server

Network File System (NFS), allow you to share your file system across different Unix and Linux hosts over the network system. NFS allow you to share different Unix and Linux server NFS requires several process to be running and mount to the target system. Please take note of the following when you are running on NFS

1. Firewall must not blocking NFS traffic

2. For NFS server, NFS and RPC process/services listed in the following tables must be exist and started

3. For NFS server, mount point must be created in /etc/exports

4. Ensure that NFS packages are installed.

5. Ensure the same user account and rights/permission exist at another share/target host.

6. Ensure that SELinux is not blocking the communication and process.

So what communication port are used for NFS traffic? We do not know, however, NFS is using dynamic ports which is under 1024.

Packages needed by NFS services (based on Centos 5.3) are:-

nfs-utils-1.0.9-40.el5
nfs-utils-lib-1.0.8-7.2.z2
portmap-4.0-65.2.2.1

The following table shows RPC, Portmap NFS process.

Process Descriptions

rpc.nfsd Daemon that 'authenticate' nfs client id login

rpc.mountd Daemon that manage NFS client login process, the daemon will read the /etc/export, shared files' right (-rwxrwxrwx, owner and group), if all the mentioned condition matched, the NFS client is granted the permission to access the NFS Server's shared file

rpc.rquotd Daemon that display quota to NFS clients

portmap Use to map the ports to RPC process

rpc.statd optional. Normally used together with rpc.lockd this is to ensure the file integrity, when a nfs file is corrupted, this daemon will repair and recover it. Howber both server and client must have the same daemon running at the same time

rpc.lockd optional. The is avoid multiple write session to NFS shared file at the same time. However in order to use this daemon, both server and client must have same daemon running.

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