Note: This is an RHCE 7 exam objective.
In this tutorial, the NFS server is called nfsserver.example.com and the NFS client nfsclient.example.com.
NFS Server Configuration
Install the file-server package group:
# yum groupinstall -y file-server
Add a new service to the firewall:
# firewall-cmd --permanent --add-service=nfs success
Reload the firewall configuration:
# firewall-cmd --reload success
Activate the NFS services at boot:
# systemctl enable rpcbind nfs-server
Note: The nfs-idmap/nfs-idmapd (changes happened with RHEL 7.1) and nfs-lock services are automatically started by the nfs-server service. nfs-idmap/nfs-idmapd is required by NFSv4 but doesn’t allow you any UID/GID mismatches between clients and server. It is only used when setting ACL by names or to display user/group names.
All permission checks are still done with the UID/GID used by the server (see this thread about nfs-idmap for more details).
Start the NFS services:
# systemctl start rpcbind nfs-server
Note1: By default, 8 NFS threads are used (RPCNFSDCOUNT=8 in the /etc/sysconfig/nfs file). This should be increased in a production environment to at least 32 (source: http://initrd.org/wiki/NFS_Setup).
Note2: Optionally, to enable SELinux Labeled NFS Support, edit the /etc/sysconfig/nfs file and paste the following line (source): RPCNFSDARGS=”-V 4.2″
Create directories to export and assign access rights:
# mkdir -p /home/tools # chmod 0777 /home/tools # mkdir -p /home/guests # chmod 0777 /home/guests
Assign the correct SELinux contexts to the new directories:
# yum install -y setroubleshoot-server # semanage fcontext -a -t public_content_rw_t "/home/tools(/.*)?" # semanage fcontext -a -t public_content_rw_t "/home/guests(/.*)?" # restorecon -R /home/tools # restorecon -R /home/guests
Note: The public_content_rw_t context is not the only available, you can also use the public_content_ro_t (only read-only) or nfs_t (more limited) contexts according to your needs.
Check the SELinux booleans used for NFS:
# semanage boolean -l | egrep "nfs|SELinux" SELinux boolean State Default Description xen_use_nfs (off , off) Allow xen to use nfs virt_use_nfs (off , off) Allow virt to use nfs mpd_use_nfs (off , off) Allow mpd to use nfs nfsd_anon_write (off , off) Allow nfsd to anon write ksmtuned_use_nfs (off , off) Allow ksmtuned to use nfs git_system_use_nfs (off , off) Allow git to system use nfs virt_sandbox_use_nfs (off , off) Allow virt to sandbox use nfs logrotate_use_nfs (off , off) Allow logrotate to use nfs git_cgi_use_nfs (off , off) Allow git to cgi use nfs cobbler_use_nfs (off , off) Allow cobbler to use nfs httpd_use_nfs (off , off) Allow httpd to use nfs sge_use_nfs (off , off) Allow sge to use nfs ftpd_use_nfs (off , off) Allow ftpd to use nfs sanlock_use_nfs (off , off) Allow sanlock to use nfs samba_share_nfs (off , off) Allow samba to share nfs openshift_use_nfs (off , off) Allow openshift to use nfs polipo_use_nfs (off , off) Allow polipo to use nfs use_nfs_home_dirs (off , off) Allow use to nfs home dirs nfs_export_all_rw (on , on) Allow nfs to export all rw nfs_export_all_ro (on , on) Allow nfs to export all ro
Note1: The State column respectively shows the current boolean configuration and the Default column the permanent boolean configuration.
Note2: Here we are interested in the nfs_export_all_rw, nfs_export_all_ro and potentially use_nfs_home_dirs booleans.
Note3: The nfs_export_all_ro boolean allows files to be shared through NFS in read-only mode but doesn’t restrict them from being used in read-write mode. It’s the role of the nfs_export_all_rw boolean to allow read-write mode.
If necessary, assign the correct setting to the SELinux booleans:
# setsebool -P nfs_export_all_rw on # setsebool -P nfs_export_all_ro on # setsebool -P use_nfs_home_dirs on
Edit the /etc/exports file and add the following lines with the name (or IP address) of the client(s):
/home/tools nfsclient.example.com(rw,no_root_squash) /home/guests nfsclient.example.com(rw,no_root_squash)
Note: Please, don’t put any space before the opening parenthesis, this would completely change the meaning of the line!
Export the directories:
# exportfs -avr exporting nfsclient.example.com:/home/guests exporting nfsclient.example.com:/home/tools # systemctl restart nfs-server
Note: This last command shouldn’t be necessary in the future. But, for the time being, it avoids rebooting.
Check your configuration:
# showmount -e localhost Export list for localhost: /home/guests nfsclient.example.com /home/tools nfsclient.example.com
NFS Client Configuration
On the client side, the commands are:
# yum install -y nfs-utils # mount -t nfs nfsserver.example.com:/home/tools /mnt