Autofs goodness in Apple’s Leopard (10.5) – Part II

In this multi-part series, we are taking a detailed look at Leopard’s autofs facility. In Part I, we have covered the basic setup of autofs in Leopard, the configuration filenames and locations, automounting home directories with nfs, direct maps and Directory Utility. In this part, we will cover the remaining special features of autofs including -fstab, -hosts and -null type of maps. Lastly, we will also find out how we can use autofs for not just NFS but also for SMB /CIFS and AFP file shares!

Special Maps: -fstab option

This is a special type of map in Leopard autofs. This map is triggered in autofs using the following like:

/Network/Servers        -fstab

Note that the mount point /Network/Servers is default in Leopard. This allows for file shares to be visible via Finder. The key values for this map is the hostname of the nfs server. The values are all the mounts that are exported by that server with the net option. Similar to direct maps, there are two ways to provide those entries to autofs. The BSD way is to edit the file /etc/fstab and add entries with the net option. The GUI/OSX way is to use Directory Utility and manage entries. Recall that Directory Utility stores its entries as XML files in /var/db/dslocal/nodes/Default/mounts.In addition to the net option, if you have large number of servers and mounts present, the use of resvport mount option is also recommended. For BSD files, the option is resvport and for Directory Utility, the option is -P.

1. Adding -fstab entries, BSD Style

   192.168.1.5:/c/man dummy nfs net 0 0

   Note that the mount point here is specified as “dummy”. This is because the fstab entry requires a mount point value. However, this map type does not use the mount point from the fstab entry at all. The mount point is specified in the auto_master file itself (/Network/Servers). So any value can be specified here (say, boo)

   
   sh-3.2# automount -vc
   automount: /net updated
   automount: /home updated
   automount: /Network/Servers updated
   automount: /usr/local/local updated
   automount: no unmounts
   
   sh-3.2# cd /Network/Servers/
   
   sh-3.2# ls
   192.168.1.5
   
   sh-3.2# cd 192.168.1.5/
   
   sh-3.2# cd c/man/
   
   sh-3.2# df -h .
   Filesystem           Size   Used  Avail Capacity  Mounted on
   192.168.1.5:/c/man  667Gi  172Gi  495Gi    26%    /Network/Servers/192.168.1.5/c/man
   

   In the Finder sidebar, you should file a clickable globe titled “All”. Click on that and navigate to the mount point in Finder!. If you do not find it in Finder, make sure to check your Finder Preferences and check the box for viewing the Connected servers.

2. Adding -fstab entries, OSX/GUI Style
   1. Bring up Directory Utility (/Applications/Utilities/Directory Utility)
   2. Click “Show Advanced Settings”.
   3. Click “Mounts”
   4. Click the lock to make the changes
   5. Click “+” to add an entry
   6. Add you entry, expand the mount parameters box and enter net in the options. If you have other options to add, add them as well, comma-separated.

At this point, you can either wait for some time for the autofs to detect the change and reload the maps or run the automount -cv command to load the changes.

Special Maps: -hosts option

This is another special map for autofs and is widely used in the Linux world as well. Traditionally, this map would be mounted on the mount point /net. This map simply uses the hostname as the key and uses all of the mounts exported by that server as its entries. It is a quick way to provide file shares from all of your NFS servers. The file share path is mount_point/hostname/nfs/server/path.

/net                    -hosts          -nobrowse,nosuid

Going back to our nfs server, let us examine what NFS shares are being exported

sh-3.2# showmount -e 192.168.1.5
Exports list on 192.168.1.5:
/c/rajeev                          *
/c/Local                           *
/c/man                             *

To access these shares, simply traverse to /net/192.168.1.5/c/rajeev, for example. It is also advised that with this option, the use of -nobrowse option is recommended as the /net option can be very chatty otherwise.

Special Maps: -null option

This map has no entries.  It is used to disable entries that occur later in the auto_master file. For example:

/shared         -null
+auto_master

This will disable any /shared entries coming from the Directory Services as a result of the +auto_master

Using Autofs with CIFS and AFP

As mentioned in the beginning of Part I, while autofs is widely used to manage NFS mounts, autofs can also be used for the management of SMB/CIFS and AFP shares. Unlike NFS, SMB/CIFS and AFP shares can be managed only using the BSD files and not using the Directory Utility. For a GUI method, just hit Go->Connect to Server and enter the SMB path in the format smb://username:password@servername/path/to/smb/share or afp://username:password@servername/path/to/afp/share

SMB/CIFS with Indirect Maps

In this example, we will use the mount point /smb and specify a indirect map auto_smb for our entries.

/smb                    auto_smb

In /etc/auto_smb, the SMB/CIFS mount entries need to be in the following format:

key -fstype=smbfs ://username:password@servername/sharepath

For example, one of my entry is as follows

Documents       -fstype=smbfs ://Documents:myverysecretpassword@192.168.1.5/Documents

Since this file contains the username and password for the CIFS shares, make sure that this file is owned by root (chown root:root /etc/auto_smb) and read permissions restricted to root (chmod 600 /etc/auto_smb). After the obligatory reloading of automounter, we verify that we can indeed mount it!

//Documents@192.168.1.5/Documents   90Gi   15Gi   75Gi    17%    /smb/Documents

AFP with Indirect Maps

The only difference between SMB/CIFS and AFP is the map entry format. For AFP, the format in the map file is

key -fstype=afp afp://username:password@servername/sharepath

As an example, if we were to mount the above Documents/ share using AFP, the map entry would look like this:

Documents   -fstype=afp afp://Documents:myverysecretpassword@192.168.1.5/Documents

That’s it! The rest of the mounting process is the same.

SMB/CIFS and AFP shares with Direct maps, -fstab

SMB/CIFS and AFP shares can be used in Direct maps and special maps like -fstab just like NFS shares. The format for the SMB/CIFS and AFP shares that need to be followed in the /etc/fstab is different from the NFS format.

• An SMB/CIFS share is specified as

  servername/path mount_point url net,automounted,url==cifs://username:password@server/path 0 0

  Note that the net option is specified for -fstab type of maps and is not specified for direct maps.

• An AFP share is specified as

  servername/path mount_point url net,automounted,url==afp://username:password@server/path 0 0

  The note about the net option applies to AFP as well.

Conclusions

The verdict is that Leopard’s autofs implementation is on par with the Unix autofs implementation. Personally, I think it is better than Linux implementation, just because of the support of the direct maps. There is room for improvement in terms of automatically showing the mounted volumes in the Finder sidebar (which would be cool) and to remove the dependency of /Network/Servers for Finder visibility. But this is a great improvement over TIGER’s automounter and we’ll take it!