Network Security - Introduction

Network Security

Introduction:

Network Security in its simplest form is concerned with making sure that unauthorised people cannot read or worse and secretly modify the message for intended recipients.
Network security consists of the provisions made in an underlying computer network infrastructure. These are policies adopted by the network administrator to protect the network and the network-accessible resources from unauthorized access and the effectiveness (or lack) of these measures combined together.
Computer security is more like providing means of self-defence to each individual citizen of the country. In computer security the measures taken are focused on securing individual computer hosts. A computer host whose security is compromised is likely to infect other hosts connected to a potentially unsecured network. A computer host's security is vulnerable to users with higher access privileges to those hosts.

Objective


1. Define Network security
2. What is cryptography?
3. Explain the encryption model
4. Discuss different e-mail securities.
5. Explain on DES
6. What is digital signature? Discuss its benefits and drawbacks.

Network Security - Continued

Most of the security problems are intentionally caused by malicious people trying to gain benefit, get attention or to harm others. Making the system secure involves more than
just keeping it from programming errors.

Few security problems



 Network security problems can be divided roughly into four categories:
1. Secrecy: It is also called confidentially. It has to do with keeping
information out of hands of unauthorised users.
2. Authentication: It deals with determining who the destination or
recipient is before revealing sensitive information or entering into a
business deal.
3. Non-repudiation: It deals with signatures. Example how do one prove
that the order was placed by the customer.
4. Integrity control: something like malicious adversary modified in transit.

Integrity and secrecy are achieved by using registered mails and locking
documents. People authenticate other people by faces, voices, and
handwriting etc. proof of signing is handled by signatures on letterhead
paper, raised seals etc. Network security can be handled at various levels or
layers.

In the physical layer, wire tapping can be avoided by enclosing transmission lines in sealed tubes. This technique is used in military systems. At data link layer, packets on a point to point line can be encrypted as they leave one machine and decrypted as they enter another. In the network layer firewalls can be installed to keep the good packets and bad packet are thrown out. IP security is also included in this layer. At transport layer, entire connections can be encrypted, end to end, and process to process. Finally issues like authentication and non-repudiation can only be handled in the application layer.

Self Assessment Questions
1. Define Kirchoff‘s principle of encryption?
2. Give the classification of network security.
3. State true or false: People authenticate other people by faces, voices, and handwriting
4. State true or false: At the physical layer firewalls can be installed
5. Issues like authentication and non-repudiation can only be handled in the _______ layer.