Adder Technology 5000 User Manual

The IP access control function uses a standard IP address and a net mask 
notation to specify both single locations and ranges of addresses. In order to 
use this function correctly, you need to calculate the mask so that it accurately 
encompasses the required address(es).

Single locations
Some of the simplest addresses to allow or deny are single locations. In this case 
you enter the required IP address into the ‘Network/Address’ field and simply 
enter the ‘Mask’ as 

255.255.255.255 (255 used throughout the mask means 

that every bit of the address will be compared and so there can only be one 
unique address to match the one stated in the ‘Network/Address’ field).

All locations
The other easy setting to make is ALL addresses, using the mask 

0.0.0.0  As 

standard, the IP access control section includes the entry: +

0.0.0.0/0.0.0.0 

The purpose of this entry is to include all IP addresses. It is possible to similarly 
exclude all addresses, however, take great care not to do this as you instantly 
render all network access void. There is a 

 should this occur. 

Address ranges
Although you can define ranges of addresses, due to the way that the mask 
operates, there are certain restrictions on the particular ranges that can be set. 
For any given address you can encompass neighbouring addresses in blocks of 
either 2, 4, 8, 16, 32, 64, 128, etc. and these must fall on particular boundaries. 
For instance, if you wanted to define the local address range: 
192.168.142.67 to 192.168.142.93 
The closest single block to cover the range would be the 32 addresses from: 
192.168.142.64 to 192.168.142.95. 
The mask needed to accomplish this would be: 

255.255.255.224  

When you look at the mask in binary, the picture becomes a little clearer. The 
above mask has the form: 

11111111.11111111.11111111.

11100000

 

Ignoring the initial three octets, the final six zeroes of the mask would ensure 
that the 32 addresses from .64 (01000000) to .95 (01011111) would all be 
treated in the same manner. See 

 for 

details.       
When defining a mask, the important rule to remember is:

There must be no ‘ones’ to the right of a ‘zero’. 

For instance, (ignoring the first three octets) you could not use a mask that had 

11100110 

because this would affect intermittent addresses within a range in an 

impractical manner. The same rule applies across the octets. For example, if you 
have zeroes in the third octet, then all of the fourth octet must be zeroes. 

The permissible mask values (for all octets) are as follows: 

Mask octet 

Binary 

Number of addresses encompassed

255 

11111111 

254 

11111110 

2 addresses 

252 

11111100 

248 

11111000 

240 

11110000 

224 

11100000 

192 

11000000 

128 

10000000 

0 

00000000 

If the access control range that you need to define is not possible using one 
address and one mask, then you could break it down into two or more entries. 
Each of these entries could then use smaller ranges (of differing sizes) that, 
when combined with the other entries, cover the range that you require.
For instance, to accurately encompass the range in the earlier example:
192.168.142.67 to 192.168.142.93 
You would need to define the following six address and mask combinations in 
the IP access control section:

Network/address entry  Mask entry

192.168.142.67 

255.255.255.255 

192.168.142.68 

255.255.255.252 

192.168.142.72 

255.255.255.248 

192.168.142.80 

255.255.255.248 

192.168.142.88 

255.255.255.252 

192.168.142.93 

255.255.255.255