University of Helsinki - Department of Computer Science
Homework                                          [suomeksi Sivu suomen kielellä] (näyttö layout) (tulostus layout) (kämmen layout)

Operating Systems II,  Spring 2004, HW 6

This will be covered in practise session during the week 19 (4-6.5.2004)

  1. Password search
    1. Problem 15.1 from text book [Stal01, p. 690]
    2. Problem 15.4 from text book
    3. What can you deduce from this?
       
  2. Password salt
    1. Problem 15.7 from text book
    2. Problem 15.8 from text book
    3. Is there real practical advantage with salt?
       
       
  3. Multilevel security
    1. Problem 15.9 from text book
    2. Problem 15.10 from text book
    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 in Lecture 12 slide 41)
    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 26.04.2004 13:48