Wireshark is free and open-source software that provides packet capture and analysis capabilities. The software is available for Mac OS X/MacOS systems. An Apple Disk Image .dmg file can be downloaded from Download Wireshark. After downloading the .dmg file, double-click on it to open it. Inside the .dmg file you will see a .pkg file and a Read me first.rtf file.
Double-click on the .pkg file to start the installation.
When you click on Continue, you will be asked to accept the software license agreement; Wireshark is licensed under the GNU General Public License Version 2.
When you agree to the license, you will be informed that the installation will take about 108 MB of space on your computer.
You will need to provide a password for an account with administrator access to complete the installation. When you've completed the installation, there will be a Wireshark.app file in the Applications folder on the system. You can double-click on it to start the application.