In recent times, the worldwide network connection is beginning to play a more important role in our lives. Since the modern societies are full of growing number of cyber crimes, network security seems to be a necessity in normal life.
There are various definitions of ¡ §network security ¡ . The American National Standard defines Network security as a ¡ §Protection of networks and their services from unauthorized modification, destruction, or disclosure. ¡ The standard also mentions that the network security ¡ §provides assurance the network performs its critical functions correctly and there are no harmful side-effects ¡ . (1)