Understanding the cURL Command for Performance Metrics

Breaking Down the Command

In the world of web development and network administration, the cURL command is a versatile tool used for transferring data using various protocols. One interesting application of this command is to measure the performance of a web server. Let’s dissect a specific cURL command to understand how it works:

curl -svo /dev/null -w "Connect: %{time_connect} \n TTFB: %{time_starttransfer} \n Total time: %{time_total} \n";

Components of the Command

  1. curl: This is the basic command call for using cURL, which initiates the data transfer.
  2. -sv: The -s flag stands for ‘silent’, which makes cURL less talkative by hiding the progress meter and error messages. The -v flag is for ‘verbose’, providing more information about the transaction. These flags might seem contradictory, but together, they suppress unnecessary details while keeping the essential info visible.
  3. /dev/null: This part redirects the output of the command to a special file that discards all data written to it. In essence, it’s used here to ignore the body of the response.
  4. -w: This flag is used to specify what data to display on the screen after the execution of the command. It stands for ‘write-out’.
  5. "Connect: %{time_connect} \n TTFB: %{time_starttransfer} \n Total time: %{time_total} \n": This is a formatted string that curl will use to display the timing statistics:
    • %{time_connect}: Shows the time it took to establish the connection to the server.
    • %{time_starttransfer}: Stands for ‘Time to First Byte’ (TTFB), indicating the time from the start until the first byte is received.
    • %{time_total}: Displays the total time taken for the operation.
  6. This is the URL to which the cURL request is made.

Practical Use

This command is particularly useful for testing the performance of web servers. By analyzing the connect time, TTFB, and total time, administrators and developers can get insights into potential bottlenecks or performance issues. For instance, a long TTFB might suggest server-side delays in processing requests.


The cURL command demonstrated here is a powerful tool for performance testing. It’s concise yet provides crucial metrics for understanding how a web server responds to requests. By mastering such commands, one can effectively monitor and optimize web server performance, ensuring better user experiences and efficient server management.

Decrypting Firefox Traffic Using Wireshark in Ubuntu GNU/Linux

Wireshark is a powerful network protocol analyzer that lets you capture and analyze real-time network traffic. By default, Wireshark does not decrypt encrypted traffic, such as HTTPS, as it is designed to maintain security and privacy. However, there are cases where decrypting network traffic can be helpful in debugging or analyzing security issues. This blog post will guide you through the steps to decrypt Firefox traffic using Wireshark in Ubuntu GNU/Linux.

Step 1: Download and Extract Firefox:

Since Ubuntu uses the snap package manager to install Firefox, which does not provide access to the file system by default, we need to download Firefox from the official website as a tar.gz archive. Open your browser and navigate to the Mozilla Firefox website ( to download the tar.gz package suitable for your Ubuntu version.

Once the download is complete, navigate to the downloaded location and extract the tar.gz file using the following command:

tar -xvf firefox-<version>.tar.gz;

Step 2: Set up the SSLKEYLOGFILE Environment Variable:

To enable Wireshark to decrypt the SSL/TLS traffic from Firefox, we need to set up the SSLKEYLOGFILE environment variable. This variable will point to a log file where Firefox will write the session keys used for encryption. Execute the following command in the terminal:

export SSLKEYLOGFILE="/home/$USER/.ssl-key.log";

This command sets the SSLKEYLOGFILE environment variable to the specified file path, which is /home/$USER/.ssl-key.log. Feel free to change the file path and name to your preference.

Step 3: Launch Wireshark and Configure Preferences:

Open the terminal and start Wireshark by entering the following command:


Once Wireshark runs, go to “Edit” in the menu bar and select “Preferences” from the dropdown menu. This will open the Wireshark Preferences window.

Step 4: Configure TLS Protocol Preferences:

In the Preferences window, locate and select “Protocols” on the left-hand side. Scroll down the protocols list and find “TLS”. Click on it to expand the options.

Within the TLS section, you will find a field labeled “(Pre)-Master-Secret log filename”. Click on the folder icon next to the field and browse to select the file path for the SSLKEYLOGFILE we set earlier.

After selecting the file path, click the “OK” button to save the changes and close the Preferences window.

Step 5: Capture and Decrypt Firefox Traffic:

With the configuration set up, you can now start capturing and decrypting Firefox traffic. Keep the Wireshark application running and launch the Firefox browser you downloaded and extracted earlier.

Wireshark will capture the network traffic as you browse the web using Firefox. You should be able to see the decrypted traffic in the Wireshark capture window.


Decrypting network traffic using Wireshark can be valuable for analyzing and troubleshooting network-related issues. This blog post covered the steps to decrypt Firefox traffic using Wireshark in Ubuntu GNU/Linux. By downloading Firefox directly from the website, setting up the SSLKEYLOGFILE environment variable, and configuring Wireshark preferences, you can capture and analyze unencrypted network traffic within Wireshark. Remember to use this technique responsibly and respect the privacy of others while conducting network analysis.

How to Keep Firefox Windows on Top in Ubuntu 18.04LTS and Newer

If you’re a frequent user of Mozilla Firefox on Ubuntu 18.04LTS or newer versions (tested up to Ubuntu Desktop 22.04LTS and 23.04), you might have encountered situations where you wished you could keep your Firefox window on top of all other open applications. This can be particularly useful when you want to reference information from a web page while working on other tasks. In this blog post, we’ll guide you through the steps to set Firefox windows on top using native GNOME features.

Gnome has a built-in feature that lets you keep any window on top of others. Here’s how to do it with Firefox:

  1. Open Firefox: Launch Firefox by clicking on its icon in the Ubuntu application launcher or by pressing Super (Windows key) and searching for “Firefox.”
  2. Open the webpage you want to keep on top.
  3. While holding down the Super (Windows key), Right-click on the Firefox application.
  4. The usual menu with the options to manage the window will appear. Select the option “Always on top”.

Please note that the “Always on top” option will appear grayed out if your window is maximized.

Upgrade O.MG Cable Firmware in Ubuntu GNU/Linux

The O.MG Cable is a popular tool for security professionals and enthusiasts, offering a covert way to gain access to a target device. To ensure its optimal performance and take advantage of new features and security enhancements, it’s important to keep the firmware up to date. In this blog post, we will guide you through the process of upgrading the firmware of an O.MG Cable on a GNU/Linux Ubuntu system using a set of simple commands.

Step 1: Installing pySerial

The first step is to install the pySerial library, which allows communication with serial ports. Open a terminal and execute the following command:

sudo pip3 install pyserial;

This command will install pySerial and its dependencies on your system. You may be prompted to enter your password to proceed with the installation.

Step 2: Cloning the O.MG-Firmware Repository

Next, we need to obtain the O.MG-Firmware repository from GitHub. Change to the desired directory in the terminal and execute the following command:

git clone;

This command will create a local copy of the O.MG-Firmware repository on your machine.

Step 3: Navigating to the O.MG-Firmware Directory

Change into the newly created O.MG-Firmware directory by running the following command:

cd O.MG-Firmware/;

This command ensures that you are in the correct directory to proceed with the firmware upgrade.

Step 4: Plugging in the O.MG Cable

Before flashing the firmware, plug in the O.MG Cable to your computer’s USB port. Ensure that the cable is properly connected and recognized by the system.

Step 5: Flashing the Firmware

To initiate the firmware upgrade process, execute the following command:

sudo python3 ./;

This command triggers the firmware flashing script using Python 3 and grants it the necessary privileges to access the USB port. You may be prompted to enter your password.

You will see progress updates and notifications on the terminal during the flashing process. Do not disconnect or interrupt the cable while the firmware is being flashed.

Once the flashing process completes, the O.MG Cable will install the latest firmware, ensuring optimal performance and security.

Conclusion: In this blog post, we provided a step-by-step guide on upgrading the firmware of an O.MG Cable on a GNU/Linux Ubuntu system. By following these commands, you can keep your O.MG Cable up to date, benefit from new features, and enhance its security. Remember to exercise caution during the firmware flashing process and avoid interrupting it. Enjoy exploring the capabilities of your upgraded O.MG Cable!