Computer Networking - Firewalls
Course material is attached for your convenience and as well as questions.
The below are simply in reference to the Questions material.
Thank you,
Lesson 1: TCP/IP Model and Internet Services
Lesson 2: Introduction to Firewalls
Lesson 3: Packet Filtering
Lesson 4: Proxying Firewalls
Lesson 5: Firewall Architecture
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Consider a firewall that protects the network shown in the figure below.
2.1 Explain the meaning of each field of the following packet filtering rule. (13 points)
Firewall rule
Packet direction
Source address
Dest address
Packet type
Source port
Dest port
ACK
action
C
Incoming
ext
132.28.6.4
TCP
23
*
*
deny
2.2 If a packet is permitted by the following packet filtering rule, that is, the packet matches the rule:
Firewall rule
Packet direction
Source address
Dest address
Packet type
Source port
Dest port
ACK
action
D
Outgoing
int
ext
TCP
*
23
*
permit
4.
2.2.1: Who is the sender program (of the packet) and where is the sender (inside the firewall or outside the firewall)? (7 points)
5.
2.2.2: Who is the receiver program (of the packet) and where is the receiver (inside the firewall or outside the firewall)? (7 points)
6.
2.2.3: What are the IP address and port number of the receiver program? (7 points)
7.
2.2.4: Could computer 168.3.144.1 be the machine on which the receiver program is running? Why? (8 points
2.2.5: Could this packet be the second sub-step packet (or signal) of the 3-way handshake process of the TCP session (or connection)? Why? (8 points)
9.
2.2.6: Could this packet be the third sub-step packet (or signal) of the 3-way handshake process of the TCP session (or connection)? Why? (8 points)
2.2.7: After the receiver program receives this packet, if the receiver wants to send a packet back to the sender, the above rule (rule D) does not authorize this packet to go through the firewall.
10.
2.2.7.1: Why rule D does not authorize this packet to go through the firewall? (8 points)
11.
2.2.7.2: A TCP connection has 3 steps (or phases): establish the connection, messages back and forth, terminate the connection. Is this packet part of Step 1, Step 2, or Step 3? (8 points)
12.
2.2.7.3: Give a rule which authorizes this new packet to go through the firewall. (8 points)
13.
2.2.7.4: Give a rule which can...
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