Wireshark – Monitoring the TCP protocol on an interface

Here shows u the steps on how to monitor the TCP protocol on a interface. Since the Ethernet is broadcasting in nature, u will find many unknown packets that both the source and destination do not belong to your IP.

1. Start the Wireshark program and click the Interface List. A window will be prompted and click Options for the interface which is going to be monitored.

Monitoring an interface
Monitoring an interface

2. Enter host in Capture Filter. So only packets associated with this IP are captured. Then click the Start button.

Set the Capture Filter
Set the Capture Filter

3. You can now find the all the packets with The on in blue is the HTTP header received from The content length in header is 3373.

View the data in the TCP packet
View the data in the TCP packet

4. If you want to filter out other protocols (like ARP in the above picture) such that only TCP packets are shown, enter tcp in Filter and click apply.

5. In order to view the whole HTTP request, right click any of the TCP packet and choose Follow TCP stream.

Follow the TCP stream
View the HTTP request

6. Now, the whole HTTP request is shown. You can filter the response by selecting the direction in the drop down box at the bottom.

View the HTTP request
View the HTTP request

7. Please note that the length 3719 is the whole length including the HTTP header. To obtain the content length, Save the HTTP request as
RAW and the remove the text including the blank line in the red box. Then the file size should be 3373.


Done =)

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