Computer network security consists of measures taken by a business or some organizations to monitor and prevent unauthorised access from the outside attackers.
Different approaches to computer network security management have different requirements depending on the size of the computer network.
For example, a home office requires basic network security, while large businesses require high maintenance to prevent the network from malicious attacks.
There are various services of network security which are as follows −
Message confidentiality or privacy means that the sender and the receiver expect confidentiality. The transmitted message must make sense to only the intended receiver. To all others, the message must be garbage. When a customer communicates with her bank, she expects that the communication is totally confidential.
Message integrity means that the data must arrive at the receiver exactly as they were sent. There must be no changes during the transmission, neither accidentally nor maliciously. As more and more monetary exchanges occur over the Internet, integrity is crucial.
For example, it would be disastrous if a request for transferring $100 changed to a request for $10,000 or $100,000. The integrity of the message must be preserved in secure communication.
Message authentication is a service beyond message integrity. In message authentication, the receiver needs to be sure of the sender's identity and that an imposter has not sent the message.
Message nonrepudiation means that a sender must not be able to deny sending a message that he or she, in fact, did send. The burden of proof falls on the receiver.
For example, when a customer sends a message to transfer money from one account to another, the bank must have proof that the customer actually requested this transaction.
In entity authentication (or user identification), the entity or user is verified prior to access to the system resources (files, for example).
For example, a student who needs to access her university resources needs to be authenticated during the logging process. This is to protect the interests of the university and the student.