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NETWORK SECURITY
SUBJECT 
COMPUTER NETWORK 
TEACHER 
Sir Saifullah Memon
Define Network: 
A Network is a series of points or nodes interconnected by 
communication paths. 
Interconnect with other networks and contain sub networks.
Define Security 
Security is “Freedom from risk or danger.“ 
The ability of a system to protect information and system 
resources with respect to confidentiality and integrity.
Network security 
 Any activities designed to protect your network 
 Target- variety of threats and stops them from entering or spreading 
on your network. 
 Handled by a network administrator.
Objective 
• Access 
• Confidentiality 
• Authentication 
• Integrity 
• Non-repudiation
History 
During the 1980s, the hackers and crimes were beginning to emerge. 
CERT was created to overcome network security issues. 
In the 1990s, Internet became public and the 
security concerns increased tremendously.
Types 
Five types of network security can aid in secure 
networking. 
•Physical security 
•Perimeter protection 
•User training and education 
•Wireless encryption protocol (WEP) 
•MAC address filtering
 We need multiple layers of security 
 Network security is accomplished 
through hardware and software. 
Network security components: 
Anti-virus and anti-spyware 
Firewall 
Intrusion prevention systems 
Virtual Private Networks
Security tools 
•Antivirus software packages 
• Secure network infrastructure 
• DNS hardware and software 
• Virtual private network 
•Identity services 
•Encryption 
•Security management
Network security technology : 
Different mechanisms to deal with these attacks. 
Cryptographic systems: 
plaintext is converted in to cipher text. 
 Secret Key Cryptography (SKC)
• Public Key Cryptography (PKC): 
• Hash Function: 
Hash function 
Plain text Cipher text
 A typical border control mechanism. 
 Metaphor for network security. 
 Designed to prevent unauthorized access to or from a 
private network.
◦ Packet Filtering Firewall 
◦ State Full Firewall 
◦Application Aware Firewall etc.. 
Network-based IDs (NIDS): 
The sensor are located at the choke in network 
It monitored, it captures all the network traffic 
and analyze each packets for malicious traffic.
 It is a good level of security 
between a web browser and a 
website. 
 There is a tunnel between 
them. 
 Clients present a certificate to 
the server to prove their 
identity.
 prevention of unauthorized access using wireless 
networks. 
Security Policies: 
 Wireless Intrusion Prevention System(WIPS) 
 Wireless Intrusion Detection System (WIDS) 
Implementation: 
Three components: sensor, server, and console.
 It is a short program aiming at securing 
communication over a network. 
Example: 
Transport layer security (TLS) 
PPP / Point-to-Point Protocol 
Internet Protocols security (IPSec)
 Network Security Services (NSS) comprises a set of 
libraries 
 It develops security-enabled client and server 
applications. 
Some are: 
Mozilla client products, including Firefox etc. 
Google Chrome 
Sun server products
Hardware Developments 
 Biometric systems -secure workstation logons 
 Smart cards -undeniable proof of a user’s identity. 
Software Developments 
 Current research develops security software using 
neural networks. 
 Objective- use neural networks for the facial 
recognition software.
The network security will be able to 
function as an immune system. 
The same set of security technology that is 
being used today with some minor 
adjustments.
Network security