Network File System (NFS) is a network file system protocol originally developed by Sun Microsystems. It allows your users or client compute to access files over a network. Linux and UNIX like operating systems (including MS-Windows) can mount file system over a network and work as they are mounted locally. This is perfect for sharing files or centralized home directories.
- Performance improvements
- Mandates security and ACL
- NFS v4 by default works over TCP s
- Easy to setup firewall option
- And much more.
You need to install the following packages:
- nfs-utils – The nfs-utils package provides a daemon for the kernel NFS server and related tools, which provides a much higher level of performance than the traditional Linux NFS server used by most users.
- portmap – The portmap package should be installed on any machine which acts as a server for protocols using RPC.
- nfs4-acl-tools – This package contains commandline and GUI ACL utilities for the Linux NFSv4 client.
Install NFS Server
Type the following command (install nfs4-acl-tools and nfs-utils on client systems too):
# yum install nfs-utils nfs4-acl-tools portmap
Loaded plugins: downloadonly, protectbase, rhnplugin, security, verify 0 packages excluded due to repository protections Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package nfs-utils.x86_64 1:1.0.9-44.el5 set to be updated ---> Package nfs4-acl-tools.x86_64 0:0.3.3-1.el5 set to be updated ---> Package portmap.x86_64 0:4.0-126.96.36.199 set to be updated --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: nfs-utils x86_64 1:1.0.9-44.el5 rhel-x86_64-server-5 390 k nfs4-acl-tools x86_64 0.3.3-1.el5 rhel-x86_64-server-5 44 k portmap x86_64 4.0-188.8.131.52 rhel-x86_64-server-5 38 k Transaction Summary ================================================================================ Install 3 Package(s) Upgrade 0 Package(s) Total download size: 472 k Is this ok [y/N]: y Downloading Packages: (1/3): portmap-4.0-184.108.40.206.x86_64.rpm | 38 kB 00:00 (2/3): nfs4-acl-tools-0.3.3-1.el5.x86_64.rpm | 44 kB 00:00 (3/3): nfs-utils-1.0.9-44.el5.x86_64.rpm | 390 kB 00:00 -------------------------------------------------------------------------------- Total 1.2 MB/s | 472 kB 00:00 Running rpm_check_debug Running Transaction Test Finished Transaction Test Transaction Test Succeeded Running Transaction Installing : portmap 1/3 Installing : nfs4-acl-tools 2/3 Installing : nfs-utils 3/3 Installed: nfs-utils.x86_64 1:1.0.9-44.el5 nfs4-acl-tools.x86_64 0:0.3.3-1.el5 portmap.x86_64 0:4.0-220.127.116.11 Complete!
Share File System
/etc/exports This is main NFS server config file which controls what directories the NFS server exports (shared with client). It use the following format:
/directory1 server.example.com(options) /directory2 192.168.1.0/24(options) /directory3 192.168.1.5(options) 192.168.1.15(options) pc202.nixcraft.net.in(options)
You can share /sales file system as follows. Edit /etc/exports, enter:
# vi /etc/exports
Add configuration as follows:
/sales 192.168.1.15(rw,sync,fsid=0) 192.168.1.16(rw,sync,fsid=0)
/sales – Share this directory.
- 192.1681.15 and 192.168.1.16 – Users from 192.168.1.15 and 192.168.1.16 are allowed to mount /sales with the read-write permissions.
- rw – Read write option.
- fsid=0 – Export a directory over NFS v4. NFSv4 has a concept of a root of the overall exported filesystem. The export point exported with fsid=0 will be used as this root. The /sales directory will be root for clients. For example, if you got /sales/mumbai, /sales/pune subdir, then client would see them as /mumbai and /pune directory. Please note that this can only export one directory with the fsid=0 option.
Save and close the file. Turn on services:
# chkconfig nfs on
# chkconfig portmap on
Start both portmap and nfs services, enter:
# service portmap start <-- for NFSv3 support
# service nfs start
Starting NFS services: [ OK ] Starting NFS quotas: [ OK ] Starting NFS daemon: [ OK ] Starting NFS mountd: [ OK ]
Please note that portmap service is not required for NFSv4.
Optional: NFS Server Configuration GUI Tool
Type the following command to use GUI tool:
NFSv4 Firewall Configuration
Edit /etc/sysconfig/iptables, enter:
# vi /etc/sysconfig/iptables
Open TCP port # 2049 which is used by NFSv4. Add the following lines, ensuring that they appear before the final LOG and DROP lines for the RH-Firewall-1-INPUT chain:
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 2049 -j ACCEPT
TCP Wrapper Configuration
TCP Wrapper is a host-based networking ACL system, used to filter network access to Internet. Edit /etc/hosts.deny, enter:
# vi /etc/hosts.deny
Add the following lines (useful for both NFSv4 and NFSv3):
Finally, edit /etc/hosts.allow and add your subnet:
Save and close the file.
NFS Client Configuration
The clients can then mount the NFSv4 export using the following command:
# mkdir /sales
# mount -t nfs4 servername:/ /sales/
# df -H
# su - username
$ cd /sales/mumbai
$ ls testfile && rm testfile
A Note About User Management
Use NIS or OpenLDAP for user management for large number of users. If you've small number of NFS clients add them to your systems using the useradd command. Make sure UID and GID matches correctly. For example, if user vivek (UID=500) is part of group vivek (gid=500) and sales group (Gid=502) on NFSv4 server, than use the following command to add user to NFSv4 client:
# grep -q '^sales' /etc/group || /usr/sbin/groupadd -g 502 sales
# /usr/sbin/useradd -s /bin/bash -d /sales -M -u 500 -g 500 -G 502 sales
# su - sales
$ ls && cd mumbai && >testfile && ls -l testfile && rm testfile
The above command matches client and server UIDs and GIDs. Otherwise you will get permission denied message on NFSv4 clients. As I said earlier, for a large number of NFSv4 users/clients, use centralized authentication systems such as NIS or OpenLDAP.
Mounting NFS File Systems Using /etc/fstab
Edit /etc/fstab, enter:
# vi /etc/fstab
Append the entry, enter:
server:/ /sales nfs4 soft,intr,rsize=8192,wsize=8192,nosuid
Save and close the file. Make sure netfs service is turned on:
# chkconfig netfs on
How Do I See NFS Statistics?
To displays statistics kept about NFS client and server activity, enter:
Server rpc stats: calls badcalls badauth badclnt xdrcall 28131 0 0 0 0 Server nfs v3: null getattr setattr lookup access readlink 10 0% 12302 58% 62 0% 166 0% 2122 10% 35 0% read write create mkdir symlink mknod 7 0% 4039 19% 52 0% 3 0% 0 0% 0 0% remove rmdir rename link readdir readdirplus 47 0% 2 0% 6 0% 0 0% 1 0% 2273 10% fsstat fsinfo pathconf commit 21 0% 13 0% 0 0% 4 0% Server nfs v4: null compound 8 0% 6726 99% Server nfs v4 operations: op0-unused op1-unused op2-future access close commit 0 0% 0 0% 0 0% 54 0% 2019 7% 0 0% create delegpurge delegreturn getattr getfh link 0 0% 0 0% 1 0% 8563 30% 2094 7% 0 0% lock lockt locku lookup lookup_root nverify 0 0% 0 0% 0 0% 78 0% 0 0% 0 0% open openattr open_conf open_dgrd putfh putpubfh 2022 7% 0 0% 14 0% 0 0% 6710 24% 0 0% putrootfh read readdir readlink remove rename 12 0% 70 0% 16 0% 7 0% 5 0% 3 0% renew restorefh savefh secinfo setattr setcltid 1 0% 2022 7% 2025 7% 0 0% 4 0% 5 0% setcltidconf verify write rellockowner 5 0% 0 0% 2003 7% 0 0%
How Do I Display Information About Shared Directories?
To see mount information for an NFS server (rpc portmap service is required), enter:
# showmount -e
# showmount -d
# showmount -a server.ip
A Note About NFSv4 Services
- The NFSv4 server works without the portmap, rpc.lockd, and rpc.statd daemons. The rpc.mountd daemon is still required on the server.
- The NFSv4 client works without rpc.lockd and rpc.statd.
- However, if you are going to mix NFSv4 and NFSv3 than make sure you start above services on both client and server.
For more information on use of the nfs server, client and additional options, please refer to the following man pages:
man 5 exports
man 8 mount
man 8 umount
man 8 nfsstat