FOG on a MAC

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Netbooting Apple Mac

Intel Macintoshs all use (U)EFI - where common PCs have a BIOS - to bootstrap and to some extent talk to hardware. Several different ways exist to make those Macs boot from network. Depending on your preference and setup choose whichever suites you.

Untested hint: Verbose Mac OS boot: sudo /usr/sbin/nvram boot-args="-v" (!topic/macenterprise/y1RnrjpvSr4)

Using stones (aka startup keys)

On startup (when you hear the sound, before Apple sign comes up) you can hold down different keys to make the Mac boot from network. Apple uses a kind of special protocol called BSDP which is partly similar to the well known DHCP protocol. But there is more to it. Find a detailed explanation here if you want to dig into it. This method is called 'Using stones' as people use stones or other similar objects to boot a whole lab of Mac clients by putting a stone on the keyboard to hold down the 'n' key - but there are other ways to achieve this too!


To make a Mac client boot from network you need to extend your DHCP server configuration. Add the following option to your subnet section:

subnet ... {

To issue special answers to Mac clients you also need to define a class:

class "Apple-Intel-Netboot" {
    match if substring (option vendor-class-identifier, 0, 14) = "AAPLBSDPC/i386";
    option dhcp-parameter-request-list 1,3,17,43,60;
    if (option dhcp-message-type = 1) {
        option vendor-class-identifier "AAPLBSDPC/i386";
        option vendor-encapsulated-options 08:04:81:00:00:67;
    filename "ipxe.efi";
    next-server x.x.x.x;

Important note: This simple config might only work with older Mac OS clients like MacBook1,1, MacBook6.2 and others. For newer models you need the advanced config

Restart the DHCP server after saving the configuration. Then booting up your Mac client hold down the 'n' key and you will see a globe spinning instead of the usual apple sign. The Mac requests an IP from the DHCP server which advises it to load iPXE via TFTP and boot that up.


That was easy. So now we can go into the details of delivering different iPXE binaries for varying Mac platforms:

class "Apple-Intel-Netboot" {
    match if substring (option vendor-class-identifier, 0, 14) = "AAPLBSDPC/i386";
    option dhcp-parameter-request-list 1,3,17,43,60;
    if (option dhcp-message-type = 1) {
        option vendor-class-identifier "AAPLBSDPC/i386";
        option vendor-encapsulated-options 08:04:81:00:00:67;
    next-server x.x.x.x;
    if (substring (option vendor-class-identifier, 15, 10) = "MacBook1,1") {
        # 32 bit
        filename "i386-efi/ipxe.efi";
    elsif (substring (option vendor-class-identifier, 15, 10) = "MacBook6,1") {
        # 64 bit
        filename "ipxe.efi";
    # add more 'elsif' here to suit your needs
    else {
        # default to ipxe.efi as new hardware is likely to be 64 bit
        log(INFO, concat ("Unknown identifier '", substring (option vendor-class-identifier, 15, 64), "' you might want to add to your config."));
        filename "ipxe.efi";

Important note: This simple config might only work with older Mac OS clients like MacBook1,1, MacBook6.2 and others. For newer models you need the advanced config

To lookup Mac models and their architecture/CPU this website comes in very handy!


Newer Macs also have a fancy version of network booting. Hold down the 'alt' key and you will see different disks and network images to boot from. To make this work you need to modify the class definition:

class "Apple-Intel-Netboot" {
    match if substring (option vendor-class-identifier, 0, 14) = "AAPLBSDPC/i386";
    option dhcp-parameter-request-list 1,3,17,43,60;
    if (option dhcp-message-type = 8) {
        option vendor-class-identifier "AAPLBSDPC";
        if (substring(option vendor-encapsulated-options, 0, 3) = 01:01:01) {
            # BSDP List
            option vendor-encapsulated-options 01:01:01:04:02:80:00:07:04:81:00:05:2a:09:0D:81:00:05:2a:08:69:50:58:45:2d:46:4f:47;
        elsif (substring(option vendor-encapsulated-options, 0, 3) = 01:01:02) {
            # BSDP Select
            option vendor-encapsulated-options 01:01:02:08:04:81:00:05:2a:82:0a:4e:65:74:42:6f:6f:74:30:30:31;
            filename "ipxe.efi";
            next-server x.x.x.x;

Important note: This advanced config is proved to work with Macmini5,2, Macmini6,2, Macbook1,1, Macbook6,1, iMac12,1 and Macbookpro9,2

For more information about the rows of hex numbers see this excellent example. And here you can find a even more advanced example configuration.

Startup Disk

When using a proper Mac OS X server one can configure a NetBoot device/server in System Preferences -> Startup Disk. See here: Startup disk.png

Unfortunatelly our previously configured NetBoot ISC DHCP server is not showing up in that dialog. It's just one simple thing preventing that. Mac OS sends a DHCPINFORM broadcast message to enumerate NetBoot images on the network. Usually DHCP messages are sent from UDP source port 68. But not in this case - Startup Disk enumeration sends DHCPINFORM with a random source port smaller 1024 (don't ask me why!). Here you can find a patch to make ICS DHCP server answer those messages properly.


As well as ISC DHCP also dnsmasq can be configured to serve as netboot server for Mac clients:


Note: Only works with old Macs like Macbook1,1 and Macbook6,1...

Add those five lines to your configuration, save and restart the service. Try booting one of your Macintoshs holding down the 'n' key while it comes up. You should see a globe - instead of the apple - on the screen!

The more advanced config for dnsmasq looks like this:



dhcp-option-force=tag:intel-macos,tag:bsdp-select,66,x.x.x.x        # TFTP server IP
dhcp-option-force=tag:intel-macos,tag:bsdp-select,67,"ipxe.efi"     # bootfile

This still does not address the issue of selecting the correct iPXE binary for 32 or 64 bit.

Using bless

An Apple Mac can be 'blessed' to boot from whichever source you want via commandline. This setting is saved in NVRAM and not changed by cloning your Macs via FOG. I'd suggest activating SSH on your Macs and use clusterssh to bless all of them without having walk to and login to each and every client.

To 'bless' your Mac turn it on and let it boot up as usual. Login and open the Terminal App and run the following command (use a proper IP instead of x.x.x.x):

sudo bless --netboot --booter tftp://x.x.x.x/ipxe.efi

According to this website the bless command is part of Mac OS X since 10.4.5. Earlier versions probably don't work that way!

No special DHCP configuration is needed for this! BUT if your server ip changes for example you'd have to run this command on all your clients again.


Newer Mac OS X releases do not allow blessing as is. You need to allow using the address with a tool called csrutil. See here for more details:

iPXE for Macintosh

As noted earlier there is a fundamental difference between Mac-EFI and PC-BIOS. Not just with configuring network boot but also when it comes to the binary being loaded via TFTP and executed on the client. To make iPXE work on Macs a lot of work has been done in 2014. Check out this thread if you are interested in the details:

The mentioned DHCP class should point the client to the correct iPXE binary (ipxe.efi). FOG includes this binary in current SVN development tree or you can download a binary from the repository if you are still using an older version of FOG:

Depending on the hardware you have this might work for you straight away. If not, please get in contact with us on the forums so we can work on it to find a solution!!

Working devices

Macbook1,1 ...

Macbook6,1 (W89452MK8PX), nVidia NForce MCP79 (PCI ID 10de:0ab0) -

Macmini5,2 (C07G3W4ADJD1), Broadcom NetXtreme BCM57765 (PCI ID 14e4:16b4) -

Macmini6,2 (C07LR0UQDY3H), Broadcom NetXtreme BCM57766 (PCI ID 14e4:1686) -

Notes from developers

Apple and its proprietary way of doing things. Simple explanation, netboot is not pxe boot. OS X is very picky about netboot. The efi iPxe file first must be named boot.efi as well as match the architecture of the machine that is booting (for you thats 64 bit) secondly not all ethernet or wifi adapters will be visible to iPxe after handoff. DHCP must point to that file as well as the boot file also.

Basically you have a few options but I will line out what we do. When I create an image, on the “master” machine I create the smallest partition possible. In that partition I add the folders: /System/Library/CoreServices/

After that I add the 64 or 32 bit ipxe file naming it boot.efi. Again for you thats a 64 bit file

Now on reboot, hold down option and select that partition. If it is able to find your nics and boot to FOG then you are in good shape!!. If it works copy the partition you just created to a usb disk. Now use that to boot your machines. Realize that you can simply select the usb disk in the boot manager and once iPxe loads up pull it out, and use it on another machine (if you are doing multiple machines). Because of limitations in iPxe do not expect a pretty FOG Menu. No background picture and such.

If your nics are not visible to the efi iPXE then you will need to use the undionly.kpxe file.


Related articles

Articles related to ISC-DHCP

BIOS and UEFI Co-Existence

ProxyDHCP with dnsmasq

FOG on a MAC

Fedora 21 Server#Verify Fedora DHCP config (if_using_DHCP)


Configure DHCP