NFS Server Setup and Client Mounting Guide for CentOS 6.5

NFS Server Installation and Configuration

This guide is based on CentOS 6.5 32-bit. Assume the server IP is 192.168.1.1, client A is 192.168.1.2, and client B is 192.168.1.3. The goal is to share a directory from the server to both clients.

1. Install NFS Service

Install the required packages using yum:

yum install nfs-utils

Key files: configuration at /etc/exports, management tool /usr/sbin/exportfs, and status command /usr/sbin/showmount.

2. Create Shared Directory

Create a directory for sharing (for production, use a separate data disk):

mkdir /download

Set appropriate permissions as needed.

3. Configure Sharing

Edit the NFS configuration file:

vi /etc/exports

Add the following line to share /download with the two clients:

/download 192.168.1.2(rw,no_root_squash) 192.168.1.3(rw,no_root_squash)

Save and exit. Verify the share:

showmount -e localhost

4. Reload Configuration

After editing, apply changes with exportfs. Common options:

• -a: Mount/unmount all entries in /etc/exports.
• -r: Remount all and update related files.
• -u: Unmount a specific share.
• -v: Verbose output.

Remount all shares:

exportfs -arv

Unmount all shares:

exportfs -auv

5. Firewall Configuration

If a firewall (e.g., iptables) is active, open NFS ports (e.g., 2049, 111). Adjust rules as needed. For testing, you may temporarily disable the firewall, but this is not recommended for production.

6. NFS Configuration Parameters Reference

• rw/ro: Read-write or read-only. Final permissions also depend on filesystem permissions.
• sync/async: sync writes data to memory and disk simultaneously; async writes to memory first, then disk asynchronously (faster but riskier).
• no_root_squash/root_squash: root_squash (default) maps root access to an anonymous user (nfsnobody) for security; no_root_squash retains root privileges (use with caution).
• all_squash: Map all users to anonymous.
• anonuid/anongid: Specify UID/GID for anonymous user mapping.

NFS Client Installation and Mounting

Using client A (IP: 192.168.1.2) as an example; client B is similar.

1. Install Client Software

Install required packages on the client:

yum install nfs-utils portmap

Note: On newer systems, portmap may be replaced by rpcbind.

2. Start Required Services

Start the RPC binding service:

/etc/init.d/rpcbind start

If NFS locking is used on the server, start the lock service:

/etc/init.d/nfslock start

3. Mount the NFS Share

Create a local mount point and mount the server's share:

mkdir /download
mount -t nfs 192.168.1.1:/download /download

Verify with df -h.

4. Unmount the Share

To unmount:

umount /download

5. Recommended Mount Options

For safer file storage, use restrictive options:

mount -t nfs -o nosuid,noexec,nodev,rw 192.168.1.1:/download /download

• nosuid: Ignore SUID permissions.
• noexec: Prevent execution of binaries.
• nodev: Do not interpret device files.

6. Auto-Mount at Boot

Edit /etc/rc.d/rc.local and add the mount command:

vi /etc/rc.d/rc.local

Add at the end:

mount -t nfs 192.168.1.1:/download /download

Note: If clients have NFS mounted, the server may not shut down properly; unmount shares first.

7. Service Management and Firewall

After server reboot, start NFS service:

service nfs start

Enable auto-start:

chkconfig --level 345 nfs on

If firewall blocks NFS, disable temporarily for troubleshooting (not recommended permanently):

chkconfig iptables off

Use chkconfig to check service status.