IP filtering is a technique used to control IP packets flow in and out of a network where Filter engine inspects at source and destination IP of incoming and outgoing packets. Here Filter engine is designed to improve the performance of the filter, i.e. to reduce the processing time of the filtering mechanism. The data structure used in the IP filter is hashing, for larger number of hosts and variety ranges IP network of hosts hashing provides much better performance than link list. Here hash function for the hash table is valid IP classes with host capacities i.e. class A, class B, class C. The IP filter engine have to compare the source and destination IP of each IP packet. In hash table technique the comparison can be done with minimum number of comparisons.