NFS Services Administrator's Guide

Configuring and Administering AutoFS
Configuring Replicated Servers for an AutoFS Directory
Chapter 3 131
AutoFS reads this entry as one line. The line is broken for
readability, and the backslash (\) instructs AutoFS that the line
continues after the line break.
3. Create and configure the /etc/netmasks file. AutoFS requires the
/etc/netmasks file to determine the subnets of local clients in a
replicated multiple server environment.
The /etc/netmasks file contains IP address masks with IP network
numbers. It supports both standard subnetting as specified in
RFC-950, and variable-length subnetting as specified in RFC-1519.
For standard subnetting, the file must contain a single line for each
network providing the network number and the network mask to use
on that network. Specify the network number and mask using the
conventional IP dot (.) notation. The network number must be a class
A, B, or C network number. For example:
network number netmask
128.32.0.0 255.255.255.0
For variable length subnetting, the /etc/netmasks file must contain
a line for each subnet where the first field is the subnet and the
second field is the netmask. The format for specifying these fields is
the same as that of standard subnetting.
Example of using the /etc/netmasks File
The following example shows how AutoFS uses the /etc/netmasks file
to determine the local client subnets in a multiple-server environment.
In this example, servers sage and thyme export or share /nfs/mount.
The IP address for server sage is 15.43.232.30, and the IP address for
the server, thyme is 15.244.10.20:
# /etc/auto_direct file
/nfs_mount sage,thyme:/nfs/mount
#/etc/netmasks file on the client basil:
#network number netmask
15.43.234.210 255.255.248.0
AutoFS uses the /etc/netmasks file and determines that the masked
value for the subnet of sage and the network number is the same (15. 42.
232. 0). This shows that the client is on the same network as sage.
AutoFS then mounts /nfs/mount from sage on the local subnet.