Uddannelser   Stillinger   Aktiviteter

Home   Personer   SiteMap   Intranet   English  

Week 10

Reading

• Section 9.1, (repetition from "Networks and Protocols"), Section 9.2, Section 9.4 and 9.5 in "Security of Computing"
• The note "Thinking About Firewalls" by Marcus J. Ranum.
• An Introduction to Intrusion Detection

Exercise problems for November 9th

1. IP Security : Transport mode AH and ESP can be combined to obtain encryption and full authentication, which ordering should be used (should AH go first or last?) and why?

2. IP Security: When should AH be prefered over ESP?

3. SSL/TLS (hard): chance_cipher_spec (ccs) is not contained in the finish message (the hash). This opens the protocol to a man-in-the-middle attack where the ccs messages are catched and dropped. Consider what would happen in the following situations:
   1. encryption is null, but a MAC is used
   2. encryption is used and also a MAC
   What attack is possible and how could such an attack be avoided?

4. SSL/TLS is the most used protocol to secure internet commerce (browser based shopping), would it give any meaning to use IPSec insted? What would the benefits be? What problems would be introduced.

   We will also discuss different firewall scenarios.

Updated 30/08-2000
henrik@it-c.dk