lec-4 Network Security Controls

Network Security Controls
3.1 Introduction:
Computer security has the same characteristics. We have many controls at our disposal.
Some are easier than others to use or implement. Some are cheaper than others to use or
implement. And some are more difficult than others for intruders to override. Figure
(1)illustrates how we use a combination of controls to secure our valuable resources. We
use one or more controls, according to what we are protecting, how the cost of protection
compares with the risk of loss, and how hard we think intruders will work to get what they
want.
There are several network security controls which can protect the network.
3.2 Encryption:
Encryption is a very powerful tool for providing privacy, authenticity, integrity, and limited
access to data. Network secure data with encryption, perhaps in combination with other
security controls.
3.2.1 Encryption Methods:
In network, encryption can be applied either between two hosts or between two
applications, so there are two forms of encryption link encryption and end-to-end
encryption .
A. Link Encryption Method:
In link encryption, data is encrypted just before it is placed on the physical communication
link. In this case, encryption occurs at layer 1 or layer 2 in the OSI model. Decryption
occures just as the communication enters the receiving computer.