+
+my $ipv4_mask_hash = {
+ '128.0.0.0' => 1,
+ '192.0.0.0' => 2,
+ '224.0.0.0' => 3,
+ '240.0.0.0' => 4,
+ '248.0.0.0' => 5,
+ '252.0.0.0' => 6,
+ '254.0.0.0' => 7,
+ '255.0.0.0' => 8,
+ '255.128.0.0' => 9,
+ '255.192.0.0' => 10,
+ '255.224.0.0' => 11,
+ '255.240.0.0' => 12,
+ '255.248.0.0' => 13,
+ '255.252.0.0' => 14,
+ '255.254.0.0' => 15,
+ '255.255.0.0' => 16,
+ '255.255.128.0' => 17,
+ '255.255.192.0' => 18,
+ '255.255.224.0' => 19,
+ '255.255.240.0' => 20,
+ '255.255.248.0' => 21,
+ '255.255.252.0' => 22,
+ '255.255.254.0' => 23,
+ '255.255.255.0' => 24,
+ '255.255.255.128' => 25,
+ '255.255.255.192' => 26,
+ '255.255.255.224' => 27,
+ '255.255.255.240' => 28,
+ '255.255.255.248' => 29,
+ '255.255.255.252' => 30
+};
+