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Transcript
EC310: Applications of Cyber Engineering
Exam #2
Alpha: ____________________
Section: ____________________
12 WEEK EXAM
NAME:
1.
2.
3.
4.
__SOLUTIONS____
This is individual work.
SHOW ALL WORK!
Write legibly to receive credit.
Turn in your equation sheet.
SCORE: ___________/100
1
SCALE
>89.5%: 31337
79.5 – 89.5%: [email protected]
69.5 – 79.5%: G33K
59.5 – 69.5%: $€RiPt K1DD13
<59.5%: n00b
EC310: Applications of Cyber Engineering
Exam #2
Lesson 11/12 – TCP/IP model/Ethernet
Alpha: ____________________
Section: ____________________
1. [7.5] List the layers of the TCP/IP model and select the letter that best describes the
main function of each. (0.5 pts for each table item, 1 pt for each letter)
Application
Transport
Network
Data Link
Physical
a.
b.
c.
d.
e.
__d__
__b__
__e__
__a__
__c__
Transfers frames across a single link connecting two nodes
Responsible for end-to-end flow, error, and congestion control
Sends bits over a channel
Processes that provide services to users such as HTTP and FTP
Responsible for routing packets and internetworking
2. [7] Two standard (10 Mbps) Ethernet topologies are illustrated in Figure 1 and
Figure 2 for a network consisting of six computers. Study the figures and answer the
questions below. (Show your work for maximum credit)
Figure 1
Figure 2
a. How much bandwidth does each user get for the network topology depicted
in Figure 1? (2 pts)
10 Mbps / 6 hosts ≈ 1.67 Mbps per host
b. How much bandwidth does each user get for the network topology depicted
in Figure 2? (2 pts)
10 Mbps / 4 hosts = 2.5 Mbps per host
c. How much bandwidth would each user get if a switch was used to connect
together the six computers in my network? (3 pts)
10 Mbps / 2 Hosts = 5 Mbps per host
2
EC310: Applications of Cyber Engineering
Exam #2
Lesson 13 – Internet Protocol
Alpha: ____________________
Section: ____________________
3. [4] Answer True or False to each of the following statements: (1 pt each)
a. An IP address is a software address.
T/F
b. IP addresses are used at the network layer.
T/F
c. There are 6 bytes in an IP address.
T/F
d. Once set, the IP address of a computer never changes. T / F
4. [3] Select from the following those that are valid IPv4 network mask?
(There maybe more than 1 correct answer)
a. /45
b. 255.255.128.0
c. 128.255.255.0
d. 255.255.240.0
e. /16
5. [9] You are a network administrator and given the following block of addresses
from your ISP
137.18.129.128/27
a. How many hosts can you support on this network? (Show your work for
maximum credit) (2 pts)
2^5 – 2 = 30
b. What is the first possible host ID? (Show your work for maximum credit)
(2 pts)
137.18.129.10000001 = 137.18.129.129
c. What is the last possible host ID? (Show your work for maximum credit)
(3 pts)
137.18.129.10011110 = 137.18.129.158
d. What is the broadcast address for your network? (Show your work for
maximum credit) (2 pts)
137.18.129. 10011111 = 137.18.129.159
3
EC310: Applications of Cyber Engineering
Exam #2
Alpha: ____________________
Section: ____________________
Lesson 14/15 – Routing Part I/II
6. [4] What feature of the Address Resolution Protocol makes it particularly
vulnerable to a spoofing attack?
An ARP reply may be trusted/accepted in the absence of a preceding ARP
request.
7. [4] Fill in the blanks for the below statements that describe the two major
categories of routing protocols. (2 pts each)
a. In _Distance Vector_ routing, a router will tell its immediate neighbors
what it knows about the entire network.
b. In _Link State_ routing, a router will tell the entire network what it knows
about its immediate neighbor (controlled flooding).
8. [8] Complete the partial routing table for Router C for the destinations listed below.
(1 pt each)
4
Destination
Destination
Next element
Total cost
A
A
5
B
I
3
C
---
0
D
I
2
E
E
5
EC310: Applications of Cyber Engineering
Exam #2
Lesson 16 – MITM Attack
Alpha: ____________________
Section: ____________________
9. [4] What does a router assume by default when another router sends it
information about the state of its links or the distance between it and other
routers?
The assumption is that each router can trust the information that other routers are
sending it.
10. [20] An attacker is located on the 3.4.5.0/25 network and wants to prevent
midshipmen from reaching a website at 8.9.7.96. He turns his computer into a
router using Loki and advertises a false network of 8.9.7.80/28 to Router A.
EC310 MID
c. There are 3 parts to complete this question.
i. Fill in the blanks to complete Router A’s routing table. (0.5 pts
each)
ii. In the line provided below Router A’s routing table, fill in the false
route the attacker would inject. (4 pts)
iii. Draw a line from the false route pointing to the location in which
it would be injected into Router A’s routing table. (2 pts)
5
EC310: Applications of Cyber Engineering
Exam #2
Alpha: ____________________
Section: ____________________
d. Will the attacker be successful in redirecting the midshipmen’s traffic?
Justify your answer. (5 pts)
No, the first and last IP addresses of the false network are 8.9.7.80 and
8.9.7.95, respectively. The webserver’s IP address does not fall within that
range. Thus, all traffic destined for the website will not go to the attacker,
but towards the webserver as normal.
e. List and briefly describe two technical solutions that could be
implemented on Router A to prevent the attacker from injecting false
routing information. (2 pts each)
Solution #1 a simple plaintext-password: added to all LSPs so each
router can authenticate the information it is receiving
Solution #2 an MD5-hash of the OSPF packet and a shared secret key: in
OSPF, routers can send the hash of the OSPF packet and a shared secret key
along with their LSP to authenticate themselves with other routers.
Solution #3 passive interface: once a network administrator sets up a passive
interface on a router, the router will ignore all routing information being
sent over that interface.
f. Who is responsible for configuring these security measures on Router A
(check one)? (1 pt)
_________ : The Network User
___ X __ : The Network Administrator
_________ : The Network Hardware Manufacturer
_________ : The Network Programmer
6
EC310: Applications of Cyber Engineering
Exam #2
Alpha: ____________________
Section: ____________________
Lesson 17/18 – Border Gateway Protocol I/II
11. [6] State and briefly describe the two problems solved by partitioning the Internet
into a number of separate Autonomous Systems vice using a single routing
protocol. (3 pts each)
Scalability - Routing tables would become huge.
Administration - owners of individual networks may want to set their own rules
for routing within their networks, without being concerned with what rules
others are electing to follow.
12. [7.5] Which (if any) of the two flavors of BGP would routers in the picture below
need to be running.
x
x
x
x
x
7
EC310: Applications of Cyber Engineering
Exam #2
Alpha: ____________________
Section: ____________________
13. [9] Given the below figure, fill in the BGP Path Table for R4. Note: R1 is preferred
over R3.
R4 BGP Path Table
Networks
Next
AS
N8, N9
R1
AS1, AS2
N10, N11, N12
R1
AS1, AS3
N13, N14, N15
R9
AS1, AS4
14. [7] AS8 wants to transmit packets of data to AS3.
Due to a peering conflict, AS8 will not allow
packets to traverse through AS7. Circle each link
in the path you will take to route packets to AS3 and
calculate the total cost.
Total Cost: 3+3+3+1 = 10
TURN IN YOUR HAND-WRITTEN EQUATION SHEET WITH YOUR EXAM
_____________________________________________________________________________________________