Installing Packer

Packer by Hashicorp is used to easily build automates images such as Metasploitable 3. Visit https://www.packer.io/downloads.html and download the version of Packer for your OS. In this instance, I've downloaded the Windows 64-bit version:

Once downloaded, extract the contents of the file. There should be one file, in this case packer.exe.

From there, create a folder anywhere you like and name it packer. I've placed it on the C: drive of my system:

At this point, you'll need to add the path to this folder in order to call the Packer application in the Command Prompt. Simply edit your environment variables and paste it into the path to packer.exe.

Go to your Control Panel and click on Advanced system settings:

In the System Properties window, under the Advanced tab, click on Environment Variables:

You should see the Path entry under User variables for admin. In the System variables box, you should also the Path variable with an entry of C:\Program Files (x86)\Common Files\Oracle|Java\javapath:..

Click on the Edit button to continue:

In the Edit environment variable, click on the New button in the top-right corner and select C:\packer from the list in the main window. Click on OK.

To test that the change was successful, launch the Command Prompt and type packer. You should return usage parameters and available commands if all is successful: