Cork Institute of Technology Master of Science in Computing in Education National Framework of Qualifications Level 9

Transcription

1 Cork Institute of Technology Master of Science in Computing in Education National Framework of Qualifications Level 9 February 2005 System and Network Management (Time: 2 Hours) Answer any THREE questions All questions carry equal marks Examiners: Dr. H. Gibbons Mr. T. Horgan Question 1 i) The management of a school have decided to migrate its computers from Microsoft Windows to Linux. After the move five administrative computers will still run Windows. Computers are currently located as follows: Location Number of Computers Staff Room 5 Computer Lab 1 30 Computer Lab 2 30 Art Room 5 Library 10 Administration 20 (15 to be moved to Linux) Using the points listed below discuss this proposed change: a. Advantages and disadvantages of moving to Linux. b. Choice of Linux distribution. c. Network services that could be offered using Linux. d. Linux user account management strategy. e. Network security issues and how these are supported in Linux. f. The integration of the five remaining Microsoft Windows machines. g. Other observations that you may have. [35 Marks] Discuss the factors that influence the choice of a hard disk layout plan to be used when installing Linux. i Explain the purpose and operation of the Linux root account. [5 Marks] Page 1

2 Question 2 i) Describe in detail the structure of DNS. What system did DNS replace and why? Describe the process of registering a.ie domain for your school. Explain in detail how Windows and Linux clients resolve HTTP addresses in this College. i Two BIND v9 configuration files are shown in Appendix A. What is the purpose of these files? Offer a detailed explanation of the contents of each file. With reference to the commands in Appendix B show how an SMTP client can send an message to an SMTP server using telnet. What benefits does MIME bring to ? v) Write about the functions and operation of a Mail Transfer Agent (MTA), Mail Delivery Agent (MDA) and a Mail User Agent (MAU). Describe the main differences between POP and IMAP. Question 3 i) What are the benefits of using Network Address Translation (NAT) on a school network? What type of NAT translations can be implemented? Using diagrams explain in detail how NAT operates. Using a network layout diagram to represent a medium sized school show how NAT differs from Port Address Translation (PAT)? Offer a detailed explanation of how PAT works. i Why are Access Control Lists (ACLs) used when configuring address translation on a Cisco router? Give an example of such a configuration. Your school network will shortly be connected via broadband to the Internet. What categories of security threats should you be aware of when managing this network? Describe a type of attach associated with each category. v) Some network protocols have weaknesses that hackers exploit. Give an example of such a protocol and describe in detail how this protocol is vulnerable. Page 2

3 Question 4 i) Compare and contrast packet filtering firewalls with stateful firewalls. i Describe the five basic guidelines that should be followed when designing a firewall system. What is the result of this Access Control List (ACL)? int f0/1 ip access-group 13 in access-list 13 permit host access-list 13 deny access-list 13 deny access-list 13 permit any Show how this ACL could be written more concisely. What is the difference between a standard and an extended ACL? Design an ACL that permits all IP traffic except pings in either direction between subnets /16 and /24. List some advantages of using an Application Gateway Firewall. v) Design an IP access list that permits TFTP traffic to TFTP servers that have host addresses ending in even numbers, denies Telnet traffic to Telnet servers that have host addresses ending in odd numbers, permits traffic to other Telnet servers, and denies all other IP traffic. Activate your list inbound on interface f0/1. (TFTP uses UDP, Telnet uses TCP.) Page 3

4 Question 5 i) The SNMP protocol defines four operations used by the management system to manipulate managed objects. Describe these operations. i Give details of the transport layer mechanism used by SNMP. The structure and naming of all SNMP variables is defined in documents called MIBs ( Management Information Base). Explain in detail the structure and operation of this system. Describe the client sever interaction that takes place during a DHCP lease request and offer. List the advantages and limitations of using DHCP. Explain function of each section of the dhcp.conf file in Appendix C. How can these setting be initialised when Linux boots? v) Explain how file ownership is controlled in Linux. You have school administration files that reside under /home/admin. You need give your 3-person management team exclusive rights to edit these files. How can this be achieved in Linux? Page 4

5 Appendix A 1. // BIND configuration file options { 4. directory "/var/named"; 5. }; 6. zone "cit.ie" in { 7. type master; 8. file "db.cit.ie"; 9. }; zone " in-addr.arpa" in { 11. type master; 12. file "db "; 13. }; zone " in-addr.arpa" in { 16. type master; 17. file "db "; 18. }; zone "." in { 21. type hint; 22. file "db.cache"; }; Listing 1. Line numbers added for clarity. 1. $TTL 3h 2. ; IN SOA terminator.movie.edu. al.robocop.movie.edu. ( h 6. 1h 7. 1w 8. 1h ) 9. ; 10. IN NS terminator.movie.edu. 11. IN NS wormhole.movie.edu. 12. ; 13. localhost IN A robocop IN A terminator IN A diehard IN A misery IN A shining IN A carrie IN A wormhole IN A IN A ; 24. bigt IN CNAME terminator 25. dh IN CNAME diehard 26. wh IN CNAME wormhole Listing 2. Line numbers added for clarity. Page 5

6 Appendix B SMTP Client Commands Command Description HELO Hello. MAIL FROM: Precedes address of sending user. RCPT TO: Precedes address of receiving user. DATA Announces an intention to start transmitting the contents of the message. NOOP Asks the server to send an OK reply. QUIT Asks the server to send an OK reply & terminate session. RESET Aborts the mail transaction. Some SMTP Server Response Codes Code Description 220 <domain> service ready. 221 <domain> service closing transmission channel. 250 Requested action completed successfully. 251 User is not local. Message will be forwarded to <path>. 354 Start sending data. End data with the string <CRLF>.<CRLF> (which signifies a period on a line by itself). 450 Action was not taken because mailbox is busy. 500 Syntax error: command not recognized. 501 Syntax error: problem with parameters or arguments. 550 Action was not taken because mailbox was not found. 551 User is not local. Try sending the message to <path>. 554 Transaction failed. Page 6

7 Appendix C 1. # dhcpd.conf 2. # 3. option domain-name "com.cit.ie"; 4. option domain-name-servers , ; 5. option netbios-name-servers ; 6. default-lease-time 600; 7. max-lease-time 7200; 8. # 8. subnet netmask { 9. option routers ; 10. option broadcast-address ; 11. option subnet-mask ; 12. range ; 13. default-lease-time 86400; 14. max-lease-time ; 15. } 16. # 17. host mc-c { 18. hardware ethernet 00:0D:56:E6:58:9F; 18. fixed-address ; 19. } 20. # 21. subnet netmask { 22. option routers ; 23. option broadcast-address ; 24. option subnet-mask ; 25. range ; 26. } Line numbers added for clarity. Page 7