NATS3 IP Address Filtering
NATS can restrict access to administration sections based on the user's Internet Protocol (IP) address.
On the page, Configuration Admin under the Admin Related heading, there are three fields for setting allowed IP addresses. Separate multiple IP addresses by with commas.
You can also filter IP addresses using a netmask. This allows or blocks a range of IP addresses in one shot. Immediately following an IP address, append a slash ("/") followed by a digit between 1 and 32.
For example, to allow admin access from all IP addresses that start with 192.168.34: 192.168.34.0/24
The /24 makes NATS look at only the first 24 bits and see if they match the IP address. Since each number field, separated by dots, represents 8 bits, /24 matches the first three fields. So, in the example, any address between 192.168.34.0 and 192.168.34.255 will be allowed to access the administration interface.
You may narrow the range to any power of 2 (2, 4, 8, 16 .... 256, etc.) by specifying a different number following the slash (/31, /30, /29, /28 .... /24, etc.).
- The Wikipedia article on Binary Subnet Masks