Due Date: April 15, 2004
- (20 points) Chapter 1, exercise 17
- (30 points) The Tick Tock Tech administration, concerned
that Wassamatta U. students are breaking into their systems, instructs
the Tech system administrators to block incoming traffic at the
Tech's perimeter firewall. In practical terms, this means that Tick
Tock Tech can initiate outbound connections, and if the external
host replies, the reply will be allowed through the firewall. But
if an external host attempts to send a message to a Tick Tock Tech
host behind the firewall, the firewall will reject the message and
the destination computer will never receive it.
- The system administrators protect, pointing out that certain
critical mechanisms for the Tech folks will no longer work. Please
name at least two types of network messages that the administration
will agree should be allowed through, but will no longer be. Explain
why they should be allowed through, and why the administration will
agree. (Remember, only network conenctions originating from outside
Tick Tock Tech's perimeter will be blocked.)
- The Nuclear Time Travel Lab, which is experimenting with time
travel, needs very accurate clocks, so they use NTP to sync their
calibration clocks with ntp.frostbite-falls.us. They have arranged
with the Frostbite Falls administrator to excchange time synchronization
messages. But the administration does not know about the NTTL's
experiments. What problems does this suggest about the way that the
administration attempted to secure the campus' computers and networks?
- Continuing part b, what procedures should the administration
have used to ensure the problems that the NTTL had would not occur?
- (20 points) Chapter 13, exercise 5
- (20 points) Discuss the use of virtual machines to enforce
the principle of least common mechanism on a single computer. In
particular, if the virtual machines are not to communicate
with one another, what conditions must they satisfy--in other words,
how must the virtual machine monitor manag their use of resources
to prevent them from communicating?
- (20 points) Chapter 23, exercise 2
- (20 points) Chapter 23, exercise 7
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