Network Security

Network Security

Network networkis a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users . Types of Networks: Local Area Network (LAN) Wide Area Network (WAN) Metropolitan Area Network (MAN)

What is network security ? Network security consists of the technologies and processes that are deployed to protect internal networks from external threats The primary goal of network security is to provide controls at all points along the network perimeter which allow access to the internal network and only let traffic pass if that traffic is authorized, valid, and of acceptable risk

Why do we need security? • Protect vital information while still allowing access to those who need it Trade secrets, medical records, etc. • Provide authentication and access control for resources • Guarantee availability of resources

Network Security Risks • Denial of Service • Attacks on the availability of networks or computer systems • Information theft • Attacks on confidential information • (e.g., customer private information, credit card information, etc.)

Network Security Risks • Intrusion • Unauthorized access to a network or computer system that could compromise the integrity and/or availability of critical systems and data • Reputation • Confidence of customers, business partners, etc. is lost. This is perhaps the biggest risk that Businesses face

Access Network An access networkis that part of a communications network which connects subscribers to their immediate service provider.

Access Network Network Access Server (NAS) : A device that functions as an access control point for users in remote locations connecting to a company's internal network or to an ISP. The NAS is meant to act as a gateway to guard access to a protected resource. This can be anything from a telephone network, to printers, to the Internet.

Network Operating System Network operating systems typically are used to run computers that act as servers. They provide the capabilities required for network operation. Network operating systems are also designed for client computers and provide functions so the distinction between network operating systems and stand alone operating systems is not always obvious.

Network Operating System Network Operating System Examples : Windows NT server Windows 2003 server

Hackers Hacker someone who attempts to break into computer systems to damage it, or for the purpose of getting illegitimate access to resources

Hackers How can hackers break into computer system ? Hackers gain access to your computer through unguarded ports in your network system hackers, Usually they use a selection of specialist software to identify weaknesses, like sub seven , Net Bus … etc

Hackers To get their intermediate base they use purpose built programs called Trojans and backdoors. It may be disguised as a game or some other kind of executable program .

Cryptography Cryptography is the science of concealing the meaning of a message from unintended recipients Only the intended recipient is able to read and understand the message

Cryptography An encryption algorithm (or a cipher) is a method of encryption and decryption. All modern algorithms use a key to control encryption and decryption; a message can be decrypted only if the key matches the encryption key . Good cryptographic systems should always be designed so that they are as difficult to break as possible

Cryptography Example: Alice wants to send a message to Bob that nobody else can read

Cryptography key key Meet me at noon Phhw ph dw qrrq Meet me at noon Alice Encrypt Dencrypt Bob

Network viruses A network virus is a self-contained program (or set of programs) that can spread copies of itself across networks, including the Internet.

Network viruses In many cases, network viruses exploit vulnerabilities in the operating system or other installed programs. and they can use legitimate network ports, such as port 80 (HTTP) and Local Area Network (LAN) or even over the Internet to spread. Some of the most famous network viruses are Nimda and SQLSlammer .

Network viruses Nimda is a virus that caused traffic slowdowns as it rippled across the Internet, It quickly spread within 22 minutes . Methods of infection: via email via open network shares via browsing of compromised web sites

Damages of network viruses Ability to quickly degrade the performance of a network, totally disabling important devices, programs and network connections and operating other programs such as (dos)and even sending themselves over the internet via emails or attachment. Once the infection spreads, fully Elimination often becomes difficult.

Wireless Network Security • The "open air" nature of wireless radio signals posses challenges for securing wireless computer networks. • Security features like • WEP • WPA • MAC

WEP(Wired Equivalent Privacy 128-bit) • WEP is an OSI Data Link layer (Layer 2) security technology that can be turned "on" or "off.“ • WEP was designed to give wireless networks the equivalent level of privacy protection .

WPA - Wi-Fi Protected Access • WPA can scramble or "encrypt" network traffic so that its contents can not easily be deciphered by snoopers.

MAC (Wireless Media Access Control ) • Wireless routers and access points (APs) incorporate access control features such as MAC address filtering that deny network requests from unwanted clients.

Network Access Control • There are three main techniques that can provide single log-in across multiple computers: 1- host-to-host authentication, 2- authentication servers, 3- user-to-host authentication.

Access Control • Host-to-Host Authentication. users authenticate themselves once to a host computer. That computer then authenticates itself to other computers. • Authentication Servers. the users authenticate themselves to the authentication server. This computer then authenticates the user to other host computers

Access Control • User-to-Host: requires the user to log-in to each host computer.

Network Security