Network Security

1. NETWORK SECURITY
1/1/2010 1
Presented By,
Name: S.Karthika.
CLASS: II-M.Sc.,Computer Science.
BATCH:2017-2019.
Incharge staf: ms.m.florance dayana.

2. COMPUTER SECURITY - also known as cyber
security or IT security, is the protection
of computer systems from the theft or damage to their
hardware, software or information, as well as from
disruption or misdirection of the services they provide.
NETWORK SECURITY - measures to protect data
during their transmission.

3. INTERNET SECURITY - Measures to protect data
during their transmission over a collection of
interconnected networks which consists of measures
to deter, prevent, detect, and correct security
violations that involve the transmission & storage of
information.

4. INTEGRITY
CONFIDENTIALITY
AVAILABILITY

5. 1.CONFIDENTIALITY
• Confidentiality refers to protecting information from
being accessed by unauthorized parties. In other
words, only the people who are authorized to do
so can gain access to sensitive data.
• Imagine your bank records. You should be able to
access them, of course, and employees at the bank
who are helping you with a transaction should be
able to access them, but no one else should.

6. 2. INTEGRITY
• The second goal of Network Security is "Integrity".
Integrity aims at maintaining and assuring the accuracy
and consistency of data.
• The function of Integrity is to make sure that the data
is accurate and reliable and is not changed by
unauthorized persons or hackers.

7. • The data received by the recipient must be exactly
same as the data sent from the sender, without change
in even single bit of data.
• cryptography plays a very major role
in ensuring data integrity.

8. 3.AVAILABILITY
Availability: The third goal of network security is
"Availability".
Availability of information refers to ensuring that
authorized parties are able to access the information when
needed.
Information only has value if the right people can access it
at the right times. Denying access to information has
become a very common attack nowadays.
How does one ensure data availability? Backup is key.
Regularly doing off-site backups can limit the damage
caused by damage to hard drives or natural disasters.

9. LEVELS OF IMPACT
 We can define 3 levels of impact from a security
breach
Low
Moderate
High

10. LOW IMPACT
 The loss could be expected to have a limited adverse effect
on organizational operations, organizational assets, or
individuals.
 The loss of confidentiality, integrity, or availability might
 (i) minor damage to organizational assets;
 (ii) minor financial loss; or
 (iii) minor harm to individuals.

11. MODERATE IMPACT
 The loss could be expected to have a serious adverse effect on
organizational operations, organizational assets, or individuals.
 A serious adverse effect means that, for example, the loss might
 (i) the functions is significantly reduced;
 (ii) result in significant damage to organizational assets;
 (iii) result in significant financial loss; or
 (iv) result in significant harm to individuals that does not
involve loss of life or serious, life-threatening injuries.

12. HIGH IMPACT
 The loss could be expected to have a severe or catastrophic
adverse effect on organizational operations, organizational
assets, or individuals.
 A severe or catastrophic adverse effect means that, for
example, the loss might
 (i) cause a severe degradation
 (ii) result in major damage to organizational assets;
 (iii) result in major financial loss; or
 (iv) result in severe or catastrophic harm to individuals
involving loss of life or serious life threatening injuries.

13. CHALLENGES OF COMPUTER SECURITY
1. Computer security is not simple
2. One must consider potential (unexpected) attacks
3. Procedures used are often counter-intuitive
4. Must decide where to deploy mechanisms
5. Involve algorithms and secret info (keys)
6. A battle of wits between attacker / admin
7. It is not perceived on benefit until fails
8. Requires constant monitoring
9. Too often an after-thought (not integral)
10. Regarded as impediment to using system

14. ASPECTS OF SECURITY
The 3 aspects of information security:
Security Attack
Security Mechanism
Security Service
Security attack:Any action that compromises the security of
information owned by an organization.
• Security mechanism:A process (or a device) that is designed to
detect, prevent, or recover from a security attack.
• Security service:A processing or communication service that
enhances the security of the data processing systems and the
information transfers of an organization.

15.  Attack - An assault on system security that derives from an intelligent
threat; that is, an intelligent act that is a deliberate attempt (especially in
the sense of a method or technique) to evade security services and
violate the security policy of a system.There are two types of attacks.
 1. Passive Attack 2.Active Attack

16. HANDLING ATTACKS
Passive attacks – A passive attack
attempts to learn or make use of
information from the system but does not
affect system resources.
Passive attacks are in the nature of
eavesdropping on, or monitoring of,
transmissions.
These attacks are difficult to detect
because they do not involve any alteration
of the data.

17. PASSIVE ATTACK - INTERCEPTION
release of message contents

18. PASSIVE ATTACK:TRAFFIC ANALYSIS
Observe traffic pattern
Traffic analysis - monitor traffic flow to determine location
and identity of communicating hosts and could observe the
frequency and length of messages being exchanged

19. Active Attack
Active attacks involve some modification of the
data stream or the creation of a false stream
It can be subdivided into four categories: masquerade,
replay, modification of messages, and denial of service:
• Masquerade of one entity as some other
• Replay previous messages
• Modify/alter (part of) messages in transit to produce
an unauthorized effect
• Denial of service - prevents or inhibits the normal
use or management of communications facilities

20. ACTIVE ATTACK: INTERRUPTION
Block delivery of message

21. ACTIVE ATTACK: FABRICATION
Fabricate message

22. ACTIVE ATTACK: REPLAY

23. ACTIVE ATTACK: MODIFICATION
Modify message

24. MODEL FOR NETWORK SECURITY
This general model shows that there are four basic tasks in designing a particular security service.
1. Design a suitable algorithm for the security
transformation
2. Generate the secret information (keys) used by
the algorithm
3. Develop methods to distribute and share the
secret information
4. Specify a protocol enabling the principles to use the
transformation and secret information for a security
service

25. MODEL FOR NETWORK ACCESS
SECURITY
using this model requires us to:
1. select appropriate gatekeeper functions to
identify users
2. implement security controls to ensure only
authorised users access designated information
or resources