Name
Source Port
Synopsis
Identifies the message’s original sender, as referenced by the 16-bit UDP port number in use by the application.
- Size
Sixteen bits.
- Notes
This field identifies the port number used by the application that created the data.
Note that RFC 768 states “Source Port is an optional field, when meaningful, it indicates the port of the sending process, and may be assumed to be the port to which a reply should be addressed in the absence of any other information. If not used, a value of zero is inserted.”
Although Source Port is optional, it should always be used.
- Capture Sample
In the capture shown in Figure 6.4, the Source Port field is set to hexadecimal 04 2c, which equates to decimal 1068.
Figure 6.4. The Source Port field- See Also
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