1. Chapter 9 Networking & Distributed Security

2. csci5233 computer security & integrity (Chap. 9) 2 Outline Overview of Networking Threats Wiretapping, impersonation, message interruption/modification, DoS Controls Encryption, authentication, distributed authentication, traffic control Email privacy: PEM, PGP Firewalls Multilevel networks

3. csci5233 computer security & integrity (Chap. 9) 3 Networking and Security Network threats arise at different points based on different technologies. So the controls must also relate to specific technologies. –The incorporation of a new technology may bring new vulnerability into a system. Examples: –Web –wireless networking –wireless Web, …

4. csci5233 computer security & integrity (Chap. 9) 4 Networking Concepts Communications, networks, distributed systems A simple view of network: Fig. 9-1, 9-2 (p.378) Client Server Host Node Link Terminal Workstation Gateway Router Repeater switch

5. csci5233 computer security & integrity (Chap. 9) 5 Networking Concepts Digital vs analog communications Communication media Copper wires (coaxial, twisted pair) Optical fiber Airwave (wireless networks) Microwave (see also p.396) Satellite communications (see also p.397) The underlying communication media are usually transparent to the users of a network.

6. csci5233 computer security & integrity (Chap. 9) 6 Networking Concepts Communication protocols Protocol stack: a layered architecture for communications, composed of both s/w and h/w Example protocol stacks: ISO’s OSI (Open Systems Interconnection) reference model pp.382-383: Fig. 9-4, 9-5, 9-6 TCP/IP suite: 4-layer architecture (application, transport, internet, physical), Table 9-1 (p.384) Ubiquitous concepts: encapsulation, multiplexing, de-multiplexing

7. csci5233 computer security & integrity (Chap. 9) 7 Networking Concepts Addressing schemes MAC addresses IP addresses Port number Types of networks: LAN WAN Internets The Internet Intranet? Extranet? Wireless networks? WLAN? Mobile network?

8. csci5233 computer security & integrity (Chap. 9) 8 Networking Concepts Network topologies: p.388 Bus topology Star topology Ring topology What kind(s) of topology does Ethernet use? What network uses the ring topology?

9. csci5233 computer security & integrity (Chap. 9) 9 Networking Concepts Distributed information systems What can be distributed? Processing Data ? Desired features of a distributed information system? Transparency (location, underlying communications, protocols, topology, software, hardware, …) Reliability Anything else?

10. csci5233 computer security & integrity (Chap. 9) 10 Threats in Networks Unique security issues in networking Shared asset Complexity (interconnections, software, hardware, media) Unknown perimeter Multiple points of vulnerabilities Anonymity Multiple, dynamically selected paths

11. csci5233 computer security & integrity (Chap. 9) 11 Threats in Networks What a malicious user can do in a network? The answer: A lot! Fig. 9-12 (p.393) See the listing on p.394. Methods of attacks: Wiretapping Impersonation message interruption message modification hacking DoS

12. csci5233 computer security & integrity (Chap. 9) 12 Methods of Attacks Wiretapping Passive vs active wiretappings Wiretapping on different media –Cables Packet sniffing (Fig. 9-15, p.398) inductance –Airwaves: microwave, WLAN (802.11b) –Satellite communications –Optical fibers The fiber itself is more secure than other media. But there are other vulnerability points. A valid assumption: All communication links can be broken. So?

13. csci5233 computer security & integrity (Chap. 9) 13 Methods of Attacks Impersonation Stealing of identity Attacks at authentication mechanisms By guessing By eavesdropping By avoidance By using a trusted system An identity that requires no authentication Well-known (default) authentication

14. csci5233 computer security & integrity (Chap. 9) 14 Methods of Attacks Denial of service (DoS) Flooding by spurious messages Flooding by modifying routing tables Any other DoS attacks?

15. csci5233 computer security & integrity (Chap. 9) 15 Summary Next: Part B - networking security controls