Setting Up an NFS Server and Client on CentOS 7.2

This guide explains how to set up an NFS server and an NFS client on CentOS 7. NFS stands for Network File System; through NFS, a client can access (read, write) a remote share on an NFS server as if it was on the local hard disk. I'll use a CentOS 7.2 minimal server as basis for the installation.

 

1 Preliminary Note

I'm using two CentOS systems here:

  • NFS Server: server.example.com, IP address: 192.168.1.100
  • NFS Client: client.example.com, IP address: 192.168.1.101

I will use the nano editor in this tutorial to edit configuration files. Nano can be installed like this.

yum -y install nano

2 Configure the Firewall

I recommend having a firewall installed. If you do not have firewalld installed yet and want to use a firewall, then install it with these commands:

yum -y install firewalld

start the firewall and enable it to be started at boot time.

systemctl start firewalld.service
systemctl enable firewalld.service

Next, open the SSH and NFS ports to ensure that you will be able to connect to the server by SSH for admin purposes and by NFS from our NFS client.

firewall-cmd --permanent --zone=public --add-service=ssh
firewall-cmd --permanent --zone=public --add-service=nfs
firewall-cmd --reload

 

3 Installing NFS

server:

On the NFS server we run:

yum -y install nfs-utils

Then enable and start the nfs server service.

systemctl enable nfs-server.service
systemctl start nfs-server.service

client:

On the client, we can install NFS as follows (this is actually the same as on the server):

yum install nfs-utils

 

4 Exporting Directories on the Server

server:

I'd like to make the directories /home and /var/nfs accessible to the client; therefore we must "export" them on the server.

When a client accesses an NFS share, this normally happens as the user nfsnobody. Usually the /home directory isn't owned by nfsnobody (and I don't recommend to change its ownership to nfsnobody!), and because we want to read and write on /home, we tell NFS that accesses should be made as root (if our /home share was read-only, this wouldn't be necessary). The /var/nfs directory doesn't exist, so we can create it and change its ownership to the user and group nfsnobody.

mkdir /var/nfs
chown nfsnobody:nfsnobody /var/nfs
chmod 755 /var/nfs

Now we must modify /etc/exports where we "export" our NFS shares. We specify /home and /var/nfs as NFS shares and tell NFS to make accesses to /home as root (to learn more about /etc/exports, its format and available options, take a look at

man 5 exports

)

nano /etc/exports
/home           192.168.1.101(rw,sync,no_root_squash,no_subtree_check)
/var/nfs        192.168.1.101(rw,sync,no_subtree_check)

(The no_root_squash option makes that /home will be accessed as root.)

Whenever we modify /etc/exports, we must run:

exportfs -a

afterwards, to make the changes effective.

 

5 Mounting the NFS Shares on the Client

client:

First we create the directories where we want to mount the NFS shares, e.g.:

mkdir -p /mnt/nfs/home
mkdir -p /mnt/nfs/var/nfs

Afterwards, we can mount them as follows:

mount 192.168.1.100:/home /mnt/nfs/home
mount 192.168.1.100:/var/nfs /mnt/nfs/var/nfs

You should now see the two NFS shares in the outputs of

df -h
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 28G 1.7G 26G 7% /
devtmpfs 909M 0 909M 0% /dev
tmpfs 919M 0 919M 0% /dev/shm
tmpfs 919M 8.6M 910M 1% /run
tmpfs 919M 0 919M 0% /sys/fs/cgroup
/dev/sda1 497M 208M 290M 42% /boot
tmpfs 184M 0 184M 0% /run/user/0
192.168.1.100:/home 28G 1.2G 27G 5% /mnt/nfs/home
192.168.1.100:/var/nfs 28G 1.2G 27G 5% /mnt/nfs/var/nfs

and

mount
[[email protected] ~]# mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=930320k,nr_inodes=232580,mode=755)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,seclabel,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu)
cgroup on /sys/fs/cgroup/net_cls type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
configfs on /sys/kernel/config type configfs (rw,relatime)
/dev/mapper/centos-root on / type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=25,pgrp=1,timeout=300,minproto=5,maxproto=5,direct)
mqueue on /dev/mqueue type mqueue (rw,relatime,seclabel)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw,relatime)
nfsd on /proc/fs/nfsd type nfsd (rw,relatime)
/dev/sda1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=188060k,mode=700)
192.168.1.100:/home on /mnt/nfs/home type nfs4 (rw,relatime,vers=4.0,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.1.101,local_lock=none,addr=192.168.1.100)
192.168.1.100:/var/nfs on /mnt/nfs/var/nfs type nfs4 (rw,relatime,vers=4.0,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.1.101,local_lock=none,addr=192.168.1.100)

 

6 Testing

On the client, you can now try to create test files on the NFS shares:

client:

touch /mnt/nfs/home/test.txt
touch /mnt/nfs/var/nfs/test.txt

Now go to the server and check if you can see both test files:

server:

ls -l /home/
[[email protected] ~]# ls -l /home/
total 0
drwx------. 2 administrator administrator 59 Jun 21 16:13 administrator
-rw-r--r--. 1 root root 0 Jun 29 13:07 test.txt
ls -l /var/nfs
[[email protected] ~]# ls -l /var/nfs
total 0
-rw-r--r--. 1 nfsnobody nfsnobody 0 Jun 29 13:07 test.txt

(Please note the different ownerships of the test files: the /home NFS share gets accessed as root, therefore /home/test.txt is owned by root; the /var/nfs share gets accessed as nobody/65534, therefore /var/nfs/test.txt is owned by 65534.)

 

7 Mounting NFS Shares at Boot Time

Instead of mounting the NFS shares manually on the client, you could modify /etc/fstab so that the NFS shares get mounted automatically when the client boots.

client:

Open /etc/fstab and append the following lines:

nano /etc/fstab
[...]
192.168.1.100:/home  /mnt/nfs/home   nfs      rw,sync,hard,intr  0     0
192.168.1.100:/var/nfs  /mnt/nfs/var/nfs   nfs      rw,sync,hard,intr  0     0

Instead of rw,sync,hard,intr you can use different mount options. To learn more about available options, take a look at

man nfs

To test if your modified /etc/fstab is working, reboot the client:

reboot

After the reboot, you should find the two NFS shares in the outputs of

df -h
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 28G 1.7G 26G 7% /
devtmpfs 909M 0 909M 0% /dev
tmpfs 919M 0 919M 0% /dev/shm
tmpfs 919M 8.6M 910M 1% /run
tmpfs 919M 0 919M 0% /sys/fs/cgroup
/dev/sda1 497M 208M 290M 42% /boot
tmpfs 184M 0 184M 0% /run/user/0
192.168.1.100:/home 28G 1.2G 27G 5% /mnt/nfs/home
192.168.1.100:/var/nfs 28G 1.2G 27G 5% /mnt/nfs/var/nfs

and

mount
[[email protected] ~]# mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=930320k,nr_inodes=232580,mode=755)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,seclabel,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu)
cgroup on /sys/fs/cgroup/net_cls type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
configfs on /sys/kernel/config type configfs (rw,relatime)
/dev/mapper/centos-root on / type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=25,pgrp=1,timeout=300,minproto=5,maxproto=5,direct)
mqueue on /dev/mqueue type mqueue (rw,relatime,seclabel)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw,relatime)
nfsd on /proc/fs/nfsd type nfsd (rw,relatime)
/dev/sda1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=188060k,mode=700)
192.168.1.100:/home on /mnt/nfs/home type nfs4 (rw,relatime,vers=4.0,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.1.101,local_lock=none,addr=192.168.1.100)
192.168.1.100:/var/nfs on /mnt/nfs/var/nfs type nfs4 (rw,relatime,vers=4.0,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.1.101,local_lock=none,addr=192.168.1.100)

 

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Comments

By: salder
Reply  

I would suggest that you add this parameter to your options section in fstab, '_netdev'.  Otherwise at boot, particularly on systems utilizing systemd, you will run into a situation that the system is trying mount the filesystem prior to a network device being up.

 

192.168.1.100:/home /mnt/nfs/home nfs rw,sync,hard,intr,_netdev 0 0 192.168.1.100:/var/nfs /mnt/nfs/var/nfs nfs rw,sync,hard,intr,_netdev 0 0

By: broken8
Reply  

when i check systemd for nfs, i saw nfs.service and nfs-server.service. What is the difference between these two services? The nfs.service keeps staying disabled and cannot be enabled. Will this affect the nfs working properly? 

By: till
Reply  

Just start the nfs-server services as shown in the tutorial. The other services does not need to be started.

By: Killll
Reply  

Use mount -t nfs -o nfsvers=3  192.168.1.100:/var/nfs /mnt/nfs/var/nfs or nfsvers=4 depending on your server and client versions if you get an error such as:

mount.nfs: an incorrect mount option was specified

By: revealz
Reply  

You can also grep -i serverip /etc/mtab >> /etc/fstab so you dont have to keep creating fstab entries once you mount it. It will grab the defaults used when mounting determined by exportfs from the server

By: bosmith
Reply  

I needed to add

firewall-cmd --permanent --zone=public --add-service=mountd

firewall-cmd --permanent --zone=public --add-service=rpc-bind

to the firewall config section

By: Bernd
Reply  

Great! That was easy with those instructios. Thank You!!

By: Naik
Reply  

Simple and Clear + comments by others for further troubleshooting.

Thanks!!

By: annahri
Reply  

I have to specify the subnetmask in /etc/exports, otherwise It produces "portmap query failed: RPC: Remote system error - No route to host"

/data   192.168.1.1/255.255.255.0(rw,sync,no_root_squash)

 

By: rebv
Reply  

Very helpful article, but running into problems for certain case. Could you advise?

Have two dirs that I would like to mount (at different times):

/dl

/dl/data

with /etc/exports looking like...

/dl clientdns(rw,fsid=0,root_squash,sync) /dl/data clientdns(ro,root_squash,sync)

I find that I can mount /dl fine onto clientdns server, though showmount does seem to error with

"clnt_create: RPC: Port mapper failure - Unable to receive: errno 113 (No route to host)"

But when unmounting and trying to mount /dl/data I get

mount.nfs: trying text-based options 'vers=4.1,addr=172.18.5.73,clientaddr=172.18.5.72' mount.nfs: mount(2): Permission denied

By: dwayne johnson The ROCK
Reply  

Best article to configure NFS, was smooth and easy did it within 10 min, Thanks.

 

By: Peter
Reply  

If the NFS client has firewall too, does it require to open any port?  The #2 seems to be intended for NFS server.