12.6 NFS
One of the most commonly used traditional systems for file sharing among Unix systems is NFS, and there are many different versions of NFS for different scenarios. You can serve NFS over TCP and UDP, with a large number of authentication and encryption options (very few of which are enabled by default, unfortunately). Because there are so many options, NFS can be a big topic, so we’ll just stick to the bare minimum of coverage.
To mount a remote directory on a server with NFS, use the same basic syntax as for mounting a CIFS directory:
# mount -t nfs server:directory mountpoint
Technically, you don’t need the -t nfs option because mount should figure this out for you, but you may want to investigate the options in the nfs(5) manual page. You’ll find several different options for security using the sec option. Many administrators on small, closed networks use host-based access control. More sophisticated methods, such as Kerberos-based authentication, require additional configuration on other parts of your system.
When you find that you’re making greater use of filesystems over a network, set up the automounter so that your system will mount the filesystems only when you actually try to use them in order to prevent problems with dependencies on boot. The traditional automounting tool was called automount, and there’s a newer version called amd, but much of this functionality has now been supplanted by the automount unit type in systemd.
Setting up an NFS server to share files to other Linux machines is more complicated than configuring the client side. You need to run the server daemons (mountd and nfsd) and set up the /etc/exports file to reflect the directories that you’re sharing. However, we won’t cover NFS servers, primarily because it’s often much more convenient to share storage over a network by simply purchasing an NAS device to handle it for you. Many of these devices are Linux based, p. 333 so they’ll naturally have NFS server support. Vendors add value to their NAS devices by offering their own administration tools to take the pain out of tedious tasks such as setting up RAID configurations and cloud backups.