Network security is classified into two categories: computer and communications
security. Computer security is all about preserving resources (data, software, service
and even hardware), guarding against unauthorized use, abuse, damage, disclosure
and modification. Communication security is about protecting data that encodes information
The aim of network security is to provide information integrity, authenticity of
communicating parties, confidentiality of the information, availability of the services,
and non- repudiation of action
Integrity of information: ensure that information has not been modified either during
transmission or storage
Confidentiality of information: ensures that information is only accessible to authorized
Authenticity of communicating parties: ensures the sender or receiver is who they
claim to be.
Availability of information services: information is available to the authorized
users, when required
Non-repudiation of the action: ensures that the sender cannot deny having sent a
Networks are constantly under threat from various sources including eavesdropping,
masquerade, man in the middle, replay, modification of information, unauthorized
access, malicious codes, denial of service attack, distributed denial of service
Eavesdropping is the unauthorized access to information during transmission.
The information accessed this way maybe
used in the future to perform more serious threats to property and life, or gain
a competitive advantage in the market place.
A hacker (see figure) has very limited
chances at intercepting your online banking. Your computer connects to the internet
through a wire from the home to a telephone terminal box outside your home. Let’s
examine several scenarios where a hacker can get at your information, hence your
Terminal box: All wires from your
neighbours join this box. It is at this terminal box where a hacker, living in your
neighbourhood would attempt to intercept your communication. But then someone could
Telephone network: This is owned by
telephone companies, a hacker has no access to your information.
Bank: Your money is as secure in the
bank as it has always been, and the bank is responsible for it.
....to be continued