Setup guide

Page 82 Dedicated Micros
IP Address Range and Subnet
When entering a range of IP addresses in the Firewall it is necessary to calculate the relevant
subnet that does not mask out the first IP address to the last IP address in the range. The
following shows the figures that are entered in the IP address field and/or the subnet mask.
The address can be written in two ways:
IP address/number of bits no subnet mask – 192.168.3.1/24
IP address and subnet mask – 192.168.3.1 255.255.255.0
If you wanted to add an address range to include IP address 1 to 12, then you would need to
find the nearest IP address and subnet that would encompasses this requirement, use the table
below to assist you with configuring this function.
The table shows the address range including the number of bits allocated to the network
address, the equivalent subnet mask for this range of addresses and the IP address that will be
included in the range, (we will use the IP address of 192.168.3.1 for the example).
Note: For details on how these figures are calculated please refer to Appendix E.
Important Note: A host cannot be allocated an IP address of 0 or 255, which means
there are really only up to 254 host addresses available in the example.
IP address Network address Included IP Address Range
192.168.3.1/24 255.255.255.0 0 - 255
192.168.3.1/25 255.255.255.128 0 - 127
192.168.3.1/26 255.255.255.192 0 - 63
192.168.3.1/27 255.255.255.224 0 – 31
192.168.3.1/28 255.255.255.240 0 – 15
192.168.3.1/29 255.255.255.248 0 – 7
192.168.3.1/30 255.255.255.252 0 – 3
192.168.3.1/31 255.255.255.254 0 - 1