Operating Systems 2014F: Assignment 9

Please submit the answers to the following questions via CULearn by just before midnight (11:55 PM) on Thursday, December 4, 2014. There 10 points in 5 questions.

Submit your answers as a single text file named "<username>-comp3000-assign9.txt" (where username is your MyCarletonOne username). The first four lines of this file should be "COMP 3000 Assignment 9", your name, student number, and the date of submission. You may wish to format your answers in Markdown to improve their appearance.

No other formats will be accepted. Submitting in another format will likely result in your assignment not being graded and you receiving no marks for this assignment. In particular do not submit a zip file, MS Word, or OpenOffice file as your answers document!

Don't forget to include what outside resources you used to complete each of your answers, including other students, man pages, and web resources. You do not need to list help from the instructor, TA, or information found in the textbook.

[2] A friend says to you that "a loopback mount over sshfs makes it easy to temporarily share files between users without changing file permissions." Explain what your friend is saying, explaining a "loopback mount" and how they interact with file permissions. (Note you may see some weird behavior!)
[2] How do processes find out that an authentication agent (ssh-agent or similar) is running and will accept connections from them? How would you expect this information to be propagated between applications?
[2] Can sshfs directly control while file is associated with which inode on the remote system (that is being mounted)? Explain briefly.
[2] How many background processes does mounting a remote filesystem over sshfs create on the client? What do each of them do?
[2] If you kill the ssh-related processes on the server (without touching those on the client) while a filesystem is mounted via sshfs, what happens to that filesystem? Why? (Describe the behaviour and give a basic explanation for it.)