macOS as NFS Client

Creating Automatically Mounted NFS Connections

The usual way to make a connection to an NFS server to access shared files is to create an automount entry and let macOS do the rest. The technical parameters to establish the connection are stored onto a directory node, and the connection will be associated with a folder, the mount point. As soon as any program, for example the Finder, opens the mount point, macOS will automatically establish the connection to the server and the shared files will become visible. Further information can be found in the introductory chapter.

Disconnecting the server is also handled automatically, as soon as the operating system realizes that files from the mount point have no longer been in use for some period. Apple’s default is set to 60 minutes. In case the mount has not been used within that time frame, it will be disconnected automatically. This way, the memory consumption and the overhead to monitor all server connections will always be as low as possible. This is important because especially in large networks, creating several thousand automount entries is not unusual.

Selecting a directory node

Automount entries are stored onto one or more directory nodes. All directory nodes currently accessible from your computer will be automatically found and listed by NFS Manager. For each node, a line Automounts from… will appear in the overview of configuration topics in the control window.

1. Click on one of the items Automounts from… in the left part of the control window below NFS Client.
2. The right part of the window shows all automount entries stored on the selected directory node. The name of the node is displayed at the top.
3. If you like to add or change entries, authenticate with the node by clicking the lock icon in the lower area. Please remember the notes from the section Authenticating with a Directory Node.

The node /Local/Default is always available. You can use it to store entries locally on this computer. In this case, the entries cannot be shared between multiple computers, however. Each client has to be configured separately.

Creating and changing automounts

To add a new entry, click the button [+] below the table. A new line with default values will be inserted. You’ll have to overwrite the values with the data applicable to your configuration:

Specify either the DNS name or the IP address of the server to which a connection should be made at NFS Server. If the server advertises its NFS services to the network using Apple’s Bonjour technology, you can also click the button Select… and choose the server from a list.

At Share Path, enter the name of the share which should be accessed on the server. The name is normally identical to the absolute path the server uses to access the shared files. If you don’t know the name, and the server has already been specified, you can click the button Select… to show a list of all NFS shares available on the server. The correct one can be selected. If NFS Manager doesn’t react after you have clicked the Select… button, this will indicate that there is a network problem contacting the selected server. In this case you’ll have to wait until macOS is canceling all connect requests to the selected server.

NFS Manager displays the server address (URL) for the automount in small print below the main entry fields. This address can be used with the Finder’s Go > Connect to Server feature to make a non-automatic, manual connection. You can drag or copy/paste the line directly into the Finder’s entry field.

An automount entry can be deleted by selecting it in table and clicking the button [—] below the table.

Mount point

The section Mount Point specifies which folder on your computer should be used

• to trigger the connection to the server, and
• to insert the data coming from the server into your own file hierarchy.

Two different modes of operation are possible:

AUTOMATIC: macOS should automatically care about creating, naming, and removing this folder. In this case, the folders of each share or server will appear in the folder Network > Servers of your computer.

To open the network folder in the Finder, select the menu item Go > Network or press the key combination ⌘ + ⇧ + K. At the UNIX level, you can reach this folder by the path /Network.

Within the folder Servers, all shares will also be divided by name (or IP address) of the server and name of the share. For example, the shared folder /Fonts of the server macserver.local will appear in the folder Network > Servers > macserver.local > Fonts.

PREDEFINED: You specify a fixed location at which the share should be triggered and inserted. The folder must be specified by its absolute Unix path. If the folder exists already, you can navigate to it by clicking the button Select….

macOS will automatically create this folder if it doesn’t exist. If the folder contains files already, the files will either be hidden while the server connection is active, or they will be overlaid (“mixed”) by the files of the share. The latter feature can optionally be activated by checking the option Overlay contents with mount point folder.

Limitations of Apple’s file system design

You should consider the following limitations when defining the mount points of NFS automounts:

• The Finder does not visualize the folder Network > Servers and the name of this folder is not translated to your preferred language. You have to use the UNIX path /Network/Servers instead, which is only visible at the command line. NFS Manager reflects this correctly in the configuration window. Note that you could create symbolic links to define Finder-visible objects that link to the actual mount points within the folder /Network/Servers.
• Apple’s automounter is not fully compatible with the volume layout of macOS that establishes a complex design of multiple APFS volumes of a volume group mounted on top of each other, together with associated APFS firmlinks that hide this layout from the user. As a workaround, it is necessary to put the path of the APFS mount point /System/Volumes/Data in front of all automounter paths, although this folder is not visualized by the Finder. NFS Manager will do this automatically for you when you specify existing folders as mount points. NFS Manager does not enforce this policy for manually entered paths, however. The automounter of macOS will automatically create firmlinks that connect the true paths to the user-visible paths when the entry is mounted.

For example, if you like to use

/Users/Shared/mnt/NFS1

as mount point, you’ll have to specify

/System/Volumes/Data/Users/Shared/mnt/NFS1

as path instead. The automounter will make the mount available at both locations.

Mount options

Each connection to an NFS server can be configured with additional options to adapt it to special needs. If the connection is made to a server which doesn’t run macOS but another operating system, it can even be necessary to switch certain options on or off, because otherwise the communication may not work correctly.

The three most important options are visible as checkboxes under the Options headline:

• Mount as read-only: When checking this option, each write operation to the share will be blocked, even if the user would have write permission. The network volume behaves like a read-only disk, like a CD or DVD for example.
• Ignore “Set User ID” privileges: If this option has been set, the special permission markers SUID and SGID will no longer be respected for files from the server. If a program on the server has been flagged with such settings, macOS would otherwise be forced to execute the program under the name of a different user or different group when the program is started, without any password entry necessary. This could even be the highest system administrator root. Because this could create a serious security hole, it is recommended to leave this option active.
• Use secure communication ports: Due to the special security model of NFS, some operating systems —Linux for example— expect that accessing clients are only considered legit if their requests are sent from ports which are usually reserved for operating system services only (i.e. the requests must not come from normal applications). Those reserved ports have port numbers less than 1024. If you access such a protected system, you must leave this option checked, otherwise all access attempts will be rejected as invalid.

A high number of further settings can be configured after clicking the button Show advanced options. These options are documented on a separate page.

When creating new automounts, NFS Manager will also enable the features Allow operations to fail if server doesn’t respond and Retry in background after initial server contact failed, which are useful in most cases. If you like to switch off these features, you must use the button Show advanced options.

Save and apply

After you have created or edited all desired automount entries you can store the entire table on the respective directory node. This will also apply the settings, i.e. macOS will be forced to re-read the table, to activate new mount points, and to deactivate removed ones, respectively. Click the button Apply at the lower right.

To discard all changes going back to the previous state, click the button Revert.

Triggering a mount

After an automount entry has been saved, macOS prepares the associated server connection and mount point. The actual connection will be established when the mount is triggered. To do this, it is sufficient to open the mount point with any application. You can also use NFS Manager:

1. Select the automount entry in the table.
2. Click the button Trigger selected mount now below the table.

Display in the Finder

Note that automatically mounted connections to NFS servers will not be represented by an icon on the Desktop or the sidebar of the Finder. This would not be useful because in large networks it is common to use several hundred connections at the same time. With so many icons, you could no longer have an overall view.

If you like to use a certain share regularly, it is recommended to drag the associated mount point into the sidebar or the toolbar of the Finder instead. With a single mouse click, you can then access the files, or trigger the mount, respectively.

NFS Manager can also be used to create an alias for the share onto your Desktop. This is done via the item Active Mounts.