Module Title: Advanced Systems Administration 2

Transcription

1 CORK INSTITUTE OF TECHNOLOGY INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ Semester 1 Examinations 2012/13 Module Title: Advanced Systems Administration 2 Module Code: COMP 7021 School: Mathematics & Computing Programme Title: Bachelor of Science in Computing in IT Support Award Bachelor of Science (Hons) in IT Management Programme Code: KITSU_7_Y3 KITMN_8_Y3 KITSP_7_Y3 External Examiner(s): Internal Examiner(s): Dr. Anthony Keane Mr. G. McSweeney Instructions: Answer 4 questions. All questions are worth equal marks. Duration: 2 Hours Sitting: Winter 2012/13 Requirements for this examination: Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination. If in doubt please contact an Invigilator. 1

2 1. (a) Some versions of UNIX are shipped with the utility program crypt. What is the purpose of crypt and briefly explain how it works. (b) Name a suitable protocol for remote login. (1 Mark) Name an unsuitable protocol for remote login. Give a reason why it s not suitable. (d) What is meant by a passive attack on a communications line? (e) Write down an example of a passive attack. Suse Linux and opensuse contain the utility visudo. What is the purpose of visudo? The struxnet worm is an example of cyber-terrorism. Briefly, explain what struxnet did. (h) Why might the cron utility be useful when doing backup? (i) What is a replay attack? (j) With reference to password encryption, what is a salt? (k) Demonstrate the diffie hellman method of shared key exchange. The formulas used are: (g b mod p) a mod p (g a mod p) b mod p (6 Marks) 2

3 2. (a) (b) Write an awk command to calculate and display the total number of hard links in the current directory. (6 Marks) Write a sed command to change all users default shell to bash (/bin/bash). What should an administrator do before carrying out the command in (b) above? (d) Write a sed command to delete all users whose default group id is (e) Suggest one advantage and one disadvantage of using an open-source application (e.g. openoffice) instead of propriety software (e.g. Microsoft Office). A user wishes to download and install an open-source application (such as openoffice). He clicks on the download icon on the application s web-site and the file openoffice.tar.gz is downloaded to his machine. What should the user do next to install the software and make it available to all users? (5 Marks) Name three different types of licenses an administrator might have to acquire when purchasing software. (h) What is the purpose of the environmental variable PS1? (1 Mark) 3

4 3. (a) List the main characteristics of cloud computing. (5 Marks) (b) What is meant by a hybrid cloud? Dropbox is an example of a cloud file-hosting service. Users can avail of limited storage free but have to pay for further capacity. Suggest some reasons why a business might use a service like dropbox for storing their data. (4 Marks) (d) What is meant by Bare-Metal Hypervisor Virtualisation? (e) With reference to disk quotas explain what hard and soft limits are. With reference to disk quotas, what is a grace period? (1 Mark) A disk quota for a user reports as follows: Filesystem blocks soft hard inodes soft hard /dev/md Explain what each of these items mean. (7 Marks) (h) What file would you edit to enable quotas in your file system? 4

5 4. (a) A user wishes to download a Linux version of Java. He is offered the following choice: jdk-7u7-linux-i586.tar.gz jdk-7u7-linux-i586.rpm What is the difference between them? (b) What is the purpose of the zypper command? (d) On the same site, a windows version of java jdk-7u7-windows-i586.exe is also available. What type of file is this and how might it be installed on a windows machine? Once the Linux version is installed, explain how a user might add the java compiler to his PATH. Assume the compiler is located in /java/bin. (e) How might the PATH in above be made permanent? (h) The java compiler file - javac is located in /java/bin. Describe how a user could make two types of link to the compiler from his current directory? (4 Marks) How would an administrator limit access to a directory of executables for specific users? Suggest three guidelines a company might consider when developing an policy. (i) What does the term RAID mean? (j) Why is RAID 0 sometimes not regarded a real RAID level? (1 Mark) 5

6 5. (a) Describe how to use the cron service works in Linux. (5 Marks) (b) Apart from cron, name another Linux scheduling service. What is the purpose ssh service? (d) (e) Suse Linux has separate directories to control services to be started at different runlevels. Why does each directory contain symbolic (soft) links to service programs rather than the actual services? (4 Marks) A part of the output of the ps command of a Linux machine contains the following: UID PID PPID CMD root httpd What does this mean? (4 Marks) With reference to process states, draw a diagram to represent the seven state model. (4 Marks) What is meant by the suspended states? (h) What is the purpose of the dispatcher? 6