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Homework                                          [suomeksi Sivu suomen kielellä]

Operating Systems II,  Spring 2005, HW 6

This will be covered in practise session during the week 18 (3-4.5.2005).
Please notice that there in no practice session on Ascencion Day 5.5.2005. Students in Thursday practice session should visit Tuesday or Wednesday groups.

  1. Password search
    1. Problem 16.1 from text book [Stal 05, p. 722] (problem 15.1 [Stal 01, p. 690])
    2. Problem 16.4 from text book [Stal 05] (problem 15.4 [Stal 01])
    3. What can you deduce from this?
       
  2. Password salt
    1. Problem 16.7 from text book [Stal 05] (problem 15.7 [Stal 01])
    2. Problem 16.8 from text book [Stal 05] (problem 15.8 [Stal 01])
    3. Is there real practical advantage with salt?
       
       
  3. Multilevel security
    1. Problem 16.10 from text book [Stal 05] (problem 15.9 [Stal 01])
    2. Problem 16.11 from text book [Stal 05] (problem 15.10 [Stal 01])
    3. Why would MAC be safer than DAC (discretionary access control)?
    4. "No read up" and "no write down" MAC policy protects data access, but not data integrity. Why? Give an example.
       
  4. User A owns file ASecret, which only A can read or write. A has program AGame, which can use file ASecret during execution? A lets user B play the game AGame and during playing B can read or write file ASecret.
    1. How would one implement the scheme described above in UNIX?
    2. How would one implement the scheme described above in W2000?
    3. How does the situation change, if B should be able read ASecret during playing, but not to write into it?
      Give new answers to parts a and b.

  5. Clustering and Grid-computing (as defined at the end of Lecture 12)
    1. Give an example application that would be suitable for Beowulf Linux Cluster'iin, but not for Windows 2000 Cluster Server. Why?
    2. Give an example application that would be suitable for clusters but not for grids. Why?
    3. Which synchronization primitives are suitable for SMP, but not for clusters? Why?
    4. Which synchronization primitives are suitable for clusters, but not for grids? Why?
Teemu Kerola 21.04.2005 16:21