Guide to Firewalls and Network Security
Chapter 1 Solutions
Review Questions
1.
Why is it important that a firewall provide a centralized security checkpoint for a
network?
Answer: A centralized checkpoint gives the network administrator a single location from
which to set up security policies and monitor traffic into and out of the company.
2.
Which of the following are important activities of a firewall?
Answer: A, B, and C are correct: The firewall won’t greet visitors. In fact, its activities are
transparent to end-users.
3.
Complete this sentence: The first kinds of firewalls were...
Answer: D: Packet filters.
4.
Why is packet filtering alone inadequate for security purposes?
Answer: A, D
5.
When does packet filtering give you an advantage over other security methods such
as proxy services?
Answer: B
6.
Most large corporate networks deploy multiple instances of what perimeter security
features? (Choose all correct answers.)
Answers: A, C
7.
When a request from a user is a received by a firewall, what actions can the firewall
take? (Choose all correct answers.)
Answer: A, B, C
8.
Most of the requests to a web site to go which TCP port?
Answer: C
9.
What can TCP do that UDP cannot do?
Answer: B. UDP is connectionless; it doesn’t confirm that a packet has been received,
while TCP is connection-oriented, which means that it does verify that packets have
reached their destination.
10.
You want to allow FTP traffic to go through your firewall. How do you do this?
Answer: C
11.
A computer connected to a network can make use of how many available ports?
Answer: 65,535
12.
Name three benefits of locating your firewall on the perimeter of a network.
Answer: You can 1) protect your whole network at once, 2) minimize the effect of an
attack, 3) can filter out various attacks, and 4) log passing traffic
Guide to Firewalls and Network Security
Chapter 1 Solutions
13.
Hackers initially try to find what network resource?
Answer: A. The others are all valuable information, but most hack attacks start with
scanning for network addresses.
14.
Which firewall is OPSEC-compliant?
Answer: B
15.
Name two reasons why a hardware firewall solution is a good choice compared to
software-only solutions.
Answer: 1) Ease of installation, 2) If your operating system is buggy or slow the
firewall is not affected.
16.
Check Point FireWall-1 was the first firewall to perform what security function?
Answer: B
17.
Which of the following is a connectionless protocol?
Answer: C
18.
For what kinds of communications is a connectionless protocol useful? (Choose all
that apply.)
Answer: A, C
19.
What does SOCKS do that other application proxy gateways do not do?
Answer: It can provide proxy services for applications that don’t have their own
proxies.
20.
Select all of the following that apply to proxy servers:
Answer: A, B
Hands-on Projects
Project 1
Answers will vary depending on the network connections available to the lab computer you are using.
Project 2
RFC 791 is entitled Internet Protocol and originally was prepared in 1981. Section 3.1 provides a diagram
of an IP packet header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| IHL |Type of Service|
Total Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Identification
|Flags|
Fragment Offset
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time to Live |
Protocol
|
Header Checksum
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Source Address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Destination Address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Options
|
Padding
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Guide to Firewalls and Network Security
Chapter 1 Solutions
Project 3
Answers will vary depending on your school’s name servers.
Project 4
Whois (or “Who Is”) is at port 43. HTTP is at port 80, FTP at 21, Simple Mail Transfer (SMTP) at 25,
POP3 at 110, Telnet at 23, and DNS at 53.
Project 5
Answers will vary depending on the network connections available to the lab computer you are using.
Project 6
Answers will vary depending on your computer’s level of security.
Case Projects
Case Project 1
The description of your computer network will vary, but it should describe the number of computers in the
network, the type of network you are using, and the type of Internet connection you have. The primary
goals of a goal include protection from outside intrusions, authentication of approved users, centralization
of management, and documentation of traffic that passes through the network. You might compare Check
Point FireWall-1, a sophisticated software only solution, and Cisco PIX, a firewall appliance.
Case Project 2
The exact solution depends on your network setup, but look for the router/hub that joins your lab’s network
to the school’s network, and through it to the Internet.
Guide to Firewalls and Network Security
Chapter 1 Solutions