Fast IP-in-subnet matcher module for IPv4 and IPv6

 Net::Subnet is a simple but fast pure Perl module for determining whether a
 given IP address is in a given set of IP subnets. It's iterative, and it
 doesn't use any fancy tries, but because it uses simple bitwise operations on
 strings it's still very fast.
 .
 The module supports both IPv4 and IPv6.