With the IP mask you define IP addresses or a range from IP addresses, which have unrestricted access to your system. If you want to put on a range by IP addresses, you can use the substitute symbol (*). A classical example would be 192.168.1.* for all PCs within local home network. With this attitude you grant all PCs with the IP addresses between 192.168.1.1 and 192.168.1.255 full access rights. Please note that your IP address range, depending upon configuration of your local network, can deviate from this example.