In the Security Administrator role, open the Security Families tool.
See "To Open the Security Families Tool" for the steps in detail.
Double-click the ALL template.
Choose Action --> Add host(s).
Click Wildcard, then give an IP address that ends in a zero (0).
For example, 192.168.0.0 or 192.168.113.0.
Assign an existing template to it.
The wildcard entry allows any host on the wildcard's network to communicate with this system at the label of the assigned template.