Prepare a USB Memstick


Be extremely careful when writing pfSense® software installation images! If the client PC contains other hard drives it is possible to select the wrong drive and overwrite a portion of that drive with the installer disk. This renders the disk completely unreadable except to certain disk recovery programs, if at all.

Using Etcher

The easiest way to create bootable installation media is to use Etcher. Etcher is available on Windows, macOS, and Linux so the procedure to write an image is the same across each supported platform. Etcher is simple to use, supports compressed image files, and has several features which help prevent users from making unintentional mistakes in the process such as selecting the wrong target drive. Additionally, unlike other methods there is no need to perform other steps before writing the image to prepare the image file or disk.

  • Download and install Etcher from

  • Insert a USB flash drive into the client computer

  • Start Etcher

    Etcher will display its main screen as shown in the following image:

  • Click Flash from file

  • Locate and select the installation image file


    Etcher can use compressed images directly, there is no need to manually decompress the image file first.

  • Click Select target

  • Click the USB flash drive to which Etcher should write the image


    Etcher attempts to hide and/or visibly mark potentially dangerous selections such as system drives, the drive containing the source image, and large drives. This makes it easier to identify the correct selection.

  • Click Select (1) to continue

  • Click Flash! to write the image to the target USB flash drive

    At this point there may be an authentication or UAC prompt to continue.


    Etcher requires elevated privileges to write USB drives. In the majority of cases, Etcher will trigger an operating system prompt for additional privileges as needed. If it does not, re-run Etcher as an administrator explicitly.

  • Wait for the flash process to complete

    If there is an error from Etcher, try another USB flash drive or follow the advice given within Etcher to resolve the problem.


    After writing the drive, the installation media will contain partitions which cannot be read by most operating systems. Ignore any operating system warnings about failing to mount the drive or prompts to format the drive.

  • Close Etcher when complete

  • Remove the USB flash drive from the client system

The installation media is now ready to use. Proceed to the installation instructions for the operating system.

Alternate Methods

For other techniques and additional guidance on writing disk images, see the reference document Writing an Installation Image to Flash Media.