Discovering the four-field UDP header
UDP has a four-field header that holds the values that keep track of the conversation, as shown in the following diagram:
Figure 9.25 – The UDP header
Now, let's take a look at each of the four UDP headers.
Analyzing the UDP header fields
Starting at the top of the UDP header, we can see User Datagram Protocol, followed by a summary of what the header represents. Below the header and summary are the UDP header fields, as shown here:
Figure 9.26 – The UDP header as shown in Wireshark
Unlike TCP, UDP has a simple header, with no additional communication details listed, such as Timestamps or SEQ/ACK analysis.
After the header, you will see the following:
- Source Port 16-bit: The source port field is the port on the sender's side. In
Frame 1, the sender is a DNS client, usingSource Port: 54585, which is not associated with any application; it is an ephemeral...
