Prepared by Dr. Samia Chelloug E-mail: samia_chelloug@yahoo.fr

1. Princess Nora Bint Abdulrahman UniversityCollege of computer and information sciencesNetworks department Networks Security (NET 536) Prepared by Dr. Samia Chelloug E-mail: samia_chelloug@yahoo.fr

2. Content • Basics of computer and network security. • Impact of network security architecture on network security. • Basics of network design. • Firewalls and virtual private networks. • Internet and wireless network security. • Impact of operating systems models on network security. • How to secure an application?

3. Textbooks • Bahrouz A.Forouzan, ‘Data Commnications and Networking’, Fourth Edition, 2007. • William Stallings, ‘Cryptography and Network Security: Principles and practice’, Fifth edition, 2011. • Eric Cole, Ronald L.Kruz, James W.Conley, ‘Network Security Fundamentales’, Wiley 2007.

4. Basics of computer and network security • Computer security: involves implementing measures to secure a single computer (protecting the ressources stored on that computer). • Network security: involves protecting all the ressources on a network. We must consider not only the computers on the network but other network devices and data transmitted across the network.

5. Basics of computer and network security Security attack: any action that comprises the security of information owned by an organization.

6. Basics of computer and network security Passive attack Active attack • Attempts to learn or make use of information from the system but does not affect system ressources. • The goal is to obtain information that is being transmitted. • Telephone converstaion, electronic e-mail message… • This type of attack is difficult to detect (it does not involve any alteration in data). • Attempts to involve some modification of the data stream or the creation of a false stream. • Based on scanning (using a search -google or any traditional method).

7. Unauthorized access E-commerce-server Your computer Data Intercept Basics of computer and network security • Why is computer and network security important? • Protect company assests (hardware and software). • Gain competive advantage: developping and maintaing effective security measures can provide an organization with a competive advantage over its competion.

8. Basics of computer and network security • Why is computer and network security important? 3. Keep your job: to secure one’s position within an organization and to ensure futur career, it is important to put into place measures that protect organizational assests.

9. Basics of computer and network security • Network security: can provide one of the five services: confidentiality, integrity, authentification, nonrepudation. • Confidentiality: the transmitted message must make sense to only the intended receiver. To the others, the message must be garbage. When a costumer communicates with her bank, she expects that her communication is totaly confidential.

10. Basics of computer and network security 2. Integrity: the data must arrive to the receiver exactly as they were sent. A request for transferring 100$ should not be changed to a request for 1000$. 3. Authentification: the receiver needs to be sure of the sender’s identity. 4.Nonrepudation : a sender must not be able to deny sending a message that he or she , in fact, did send.

11. Security Detection Prevention Response Basics of computer and network security • Security trinity: Network security is based on: prevention, detection, and response. • Security trinity should be the foundation for all security policies.

12. Basics of computer and network security -Prevention: in developping network security schemes, any organization should emphasize preventive measures over detection and response. It is more efficient and much more cost effective to prevent a security attack than to detect or repond to one. -Detection: once the preventive measures fail, procedures need to be put in place to detect immediatly to detect the araised attack. -Response: we need to develop a plan that identifies the appropriate response to a security atatck (who is responsable to execute some actions, what is the appropriate action ?)

13. Basics of computer and network security • Challenges of computer and network security: • Security is not simple as it might first appear to the novice: we need to consider potential attacks . Security mechanisms typically involve more than a paticular algorithm. • Having designed various security mechanisms, it is necessary to decide where to use them (physical and logical sense). What points in a network are certain secured mechanisms needed? What layer or layers of our architecture should mechanisms be placed?