Manually Upgrade FOS Kernel

The kernel that the fog server uses to image clients with can be out of date and cause issues for some computers with newer network cards. Ideally, you can use the built in kernel update tool, but if you are experiencing issues using the tool you can do a manual upgrade instead. Here is the method for manually updating the kernels.


Manually loading different kernel versions can be pretty handy to test with the different hardware you have. Going straight to a new kernel - while not very likely - can cause an issue with some devices. So instead you might assign a different kernel to one or maybe a few machines through the kernel parameter in the hosts’ settings: Kernel

Downloading the Kernels

To begin, ensure you have the files bzImage and bzImage32 located in /var/www/html/fog/service/ipxe/

With root or sudo, perform a ls to look.

ls -la /var/www/html/fog/service/ipxe

On some distros (mainly older ones) the root path is ``/var/www/fog…``, this is also a symlink on some distros (sometimes created by the fog installer). Most distros use this root path for the fog httpd/apache site ``/var/www/html/fog…``

After confirming the files exist, create a folder called Backup in the same location, and move the current bzImage files there. This will be helpful in case you quickly need to revert any changes you made.

Next, download the newer kernel files from

Use a web browser on another computer or wget/curl on the FOG server if you know what to do.

Be sure to choose the highest number kernel you can find, alongside the latest date. Also, ensure you download both the 32 bit (bzImage32) and 64 bit (bzImage) kernel.

Rename Files

In case you don’t want to overwrite your current kernel files you better rename the new ones to use a different filename. That way you can have several versions available. For example you might have some flacky hardware that doesn’t properly run the latest kernel you want to use for all your other devices.

Move Files

Next step is to move these files to the location specified in the beginning, you may need root or sudo acces to move them there. you can use either the mv command on the server or FTP it. As a reminder the location is:



Next, with root or sudo, enter:

ls -la /var/www/html/fog/service/ipxe

Take note of the owner listed in the files located in this directly. In my case the owner is root, so I changed the owner and matched the permissions found in the other files.

changing owner of the new kernels:

chown apache:apache /var/www/html/fog/service/ipxe/bzImage*

To confirm, rerun the list command with root/sudo and ensure all the permissions and owners looks the same:

ls -la /var/www/html/fog/service/ipxe

Version Check

To verify or check the version of your kernel binaries you ca simply use the file command on most modern Liux systems:

file /var/www/html/fog/service/ipxe/bzImage*