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Writing ISO Images

A disc will need to be burned from a downloaded ISO image if it will be used with a physical optical drive. Since the downloaded file is a CD image, it will need to be burned appropriately for image files — not as a data CD containing the single ISO file. Procedures for doing so will vary by OS and available software.

Before the image can be burned, it must be decompressed. The .gz extension on the file indicates that it is compressed with gzip. This can be decompressed on Windows using 7-Zip, or on BSD/Linux/Mac with the gunzip or gzip -d commands.

Burning in Windows

Virtually every major disc burning software package for Windows includes the ability to burn ISO images. Refer to the documentation of the disc burning program being used. A Google search with the name of the software and “burn iso” should help to locate instructions.

Burning with Nero

It is easy to burn ISO images with Nero. Start by right clicking on the ISO file, then click Open With, and select Nero. The first time this is done, it may be necessary to select Chose Default Program and then pick Nero from the list. This same process should work with other commercial CD burning software.

Burning with ISO Recorder

If using Windows XP, 2003, or Vista, the freely available ISO Recorder tool may be used. Download and install the appropriate version of ISO Recorder for the operating system being used, then browse to the folder on the drive containing the pfSense® ISO, right click the file, and click Copy image to CD.

Other Free Burning Software

Other free options for Windows users include CDBurnerXP, InfraRecorder and ImgBurn, among others.

Before downloading and installing any program, check its feature list to make sure it is capable of burning an ISO image.

Burning in Linux

Linux distributions such as Ubuntu typically include some form of GUI burning application that can handle ISO images. If one is integrated with the window manager, right click on the ISO file and choose Write disc to. Other popular choices include K3B and Brasero Disc Burner.

If a GUI burning program is not installed, it may still be possible to burn from the command line. First, determine the burning device’s SCSI ID/LUN (Logical Unit Number) with the following command:

# cdrecord --scanbus
Cdrecord-Clone 2.01 (i686-pc-linux-gnu) Copyright (C) 1995-2004 Jörg Schilling
Linux sg driver version: 3.1.25
Using libscg version 'schily-0.8'.
   0,0,0 100) 'LITE-ON ' 'COMBO LTC-48161H' 'KH0F' Removable CD-ROM


The SCSI ID/LUN is 0,0,0.

Burn the image as in the following example, replacing <max speed> with the speed of the burner and lun with the SCSI ID/LUN of the recorder:

# cdrecord --dev=lun --speed=<max speed> pfSense-CE-2.4.4-RELEASE-p3-amd64.iso

Burning in FreeBSD

FreeBSD includes the burncd program in its base system which can be used to burn ISO images:

# burncd -s max -e data pfSense-CE-2.4.4-RELEASE-p3-amd64.iso fixate

For more information on creating CDs in FreeBSD, please see the entry for CD burning in the FreeBSD Handbook at

Verifying the CD

Now that the CD is prepared, verify it was burned properly by viewing the files contained on the CD. More than 20 folders should be visible, including bin, boot, cf, conf, and more. If only one large ISO file is seen, the CD was not burned properly. Repeat the steps listed earlier for burning a CD, and be sure to burn the ISO file as a CD image and not as a data file.