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Labs

Utilize TCPDump for Packet Capture

In this hands-on lab, we will learn how to capture network traffic using the `tcpdump` command line tool. We will install and configure `tcpdump` on `Server1` to capture web traffic coming from `Client1`. **Note**: In the lab, you now must specify the capture interface now that the instance has ens5 instead of eth0. By default, tcpdump captures packets on eth0. ``` sudo tcpdump tcp port 80 -i ens5 -w capture.pcap ```

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Labs

Path Info

Level
Clock icon Intermediate
Duration
Clock icon 1h 0m
Published
Clock icon Nov 14, 2018

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Table of Contents

  1. Challenge

    Install Tcpdump

    Your first task is to install tcpdump. In the video, I ran the command as root — your command will be slightly different.

    1. Run the following command:
    sudo yum install tcpdump
    
    1. When prompted, enter the password for cloud_user.
  2. Challenge

    Begin the Packet Capture

    Begin the packet capture process. You will want to apply a capture filter to limit tcpdump to capture only web requests.

    sudo tcpdump tcp port 80 -i ens5 -w capture.pcap
    
  3. Challenge

    Generate Traffic

    Because this isn't a public web server, you need to generate traffic from Client1 (10.0.1.11) to Server1 (10.0.1.10). This should be completed while the capture is running. I just ran curl on the headers of Server1 in the Solution video, which can be completed by running the following command from Client1 a few times:

    curl -I 10.0.1.10
    
  4. Challenge

    Cancel the Capture and View the Results

    1. After some traffic has been generated, cancel the running capture and view the file.
    #tcpdump -r capture.pcap
    
    1. Move the file to /root/ if it's not there already.
    sudo mv capture.pcap /root/capture.pcap
    

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