Computer network security

As computers and computer communication has become an important part of the global trading and financial world, the need for secure communication has become crucial. Companies do business over the Internet and they transfer sensitive data from one branch to another over public telephone or data lines. Also ordinary people transmit private and sensitive information over the Internet when they shop or use Internet-based banking services. If these transactions are not properly secured, ``everyone'' can obtain information which can be used against one or both parts of the communication.

Without any security mechanisms, the Internet is vulnerable to a wide variety of attacks. Even with the security mechanisms used in todays Internet, attacks occasionally succeed in disrupting the function of the global Internet. Clearly, robust security mechanisms for the basic network services is needed in most kind of computer networks.