Kaspersky Internet Security 2009

	Useful links
	System security in Kaspersky Internet Security 2009: general information and working principles

A method to allocate IP-addresses using Classless Inter-Domain Routing (CIDR) has been implemented in Kaspersky Internet Security 2009 unlike the product’s previous versions 6.0 and 7.0. You can find the setting when creating rules for the Firewall component:

CIDR is the method of IP-addressing which allows managing the range of IP-address flexibly, without rigid frames of the Class Inter-Domain Routing. CIDR allows using the end resource of IP-addresses economically, thus enhancing efficiency of Kaspersky Internet Security 2009.

CIDR uses Variable Length Subnet Mask (VLSM) whereas in Class Inter-Domain Routing the mask length is strictly set by 0,1,2 or 3 bytes.

For example, let’s take a record of the range of IP-addresses as 10.96.0.0/11. In this case the subnet mask will look as 11111111 11100000 00000000 00000000, or as 255.224.0.0 in a decimal view. 11 bits of the IP-address are allocated to the number of network; the other 21 bits (32-11= 21) of the full address are allocated to the local address in the network. To sum up, 10.96.0.0/11 is a range of addresses from 10.96.0.1 to 10.127.255.255.

Remember, when defining CIDR-addressing in the networks of the IP-protocol version 4 (IPv4) in any case the rule will be applied to the whole network.

To convert IP-addresses into CIDR Kaspersky Lab’s experts recommend using any web site which provides free service of converting IP-addresses to CIDR-addressing (for example, the web site http://ip2cidr.com/).