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WIRESHARK ASSIGNMENT – 4 (UDP)

1. Select one UDP packet from your trace. From this packet, determine how many fields there are in the UDP header. (You shouldn’t look in the textbook! Answer these questions directly from what you observe in the packet trace.) Name these fields.

Answer : The fields that are in UDP are as follows : Source Port, Destination Port, Length and Checksum

Result : Source Port: 57544 (57544) ; Destination Port: 53 (53) ; Length: 49 ; checksum: 0xd587 [validation disabled]

2. By consulting the displayed information in Wireshark’s packet content field for this packet, determine the length (in bytes) of each of the UDP header fields.

Answer : The UDP header has four fields and each field consists of two bytes length.

3. The value in the Length field is the length of what? (You can consult the text for this answer). Verify your claim with your captured UDP packet.

Answer : The value in the Length field is 49 bytes. This value is the sum of both the requested data (41 in bytes) and the length of the header fields (8 bytes i.e 2 bytes for each field, totally 4 fields in the header)

In our captured UDP packet, the total value in length field = 41 + 8 = 49 bytes

4. What is the maximum number of bytes that can be included in a UDP payload? (Hint: the answer to this question can be determined by your answer to 2. above)

Answer : Maximum number of bytes for UDP payload = ( 2^16 – 1 ) – Header byte i.e 8 bytes

Therefore, the UDP payload maximum number of bytes is 65527 bytes.

5. What is the largest possible source port number? (Hint: see the hint in 4.)

Answer : The largest possible source port number s 65535. (The port number ranges from 0 to 65535) The port number is a 16 bit number.

6. What is the protocol number for UDP? Give your answer in both hexadecimal and decimal notation. To answer this question, you’ll need to look into the Protocol field of the IP datagram containing this UDP segment (see Figure 4.13 in the text, and the...