PXE over IPv4

[Faurel]

Hi,

I’m a complete newbie to Fog, so I apologize in advance for the likely simplicity of my problem…
And I’m not a native english speaker. Sorry for that too.

I can’t use PXE, I keep getting the following error message :

FYI, my Fog server is installed on an Ubuntu 24.04 virtual machine, and I’m trying to make an image of a brand new Microsoft Surface.

I have modified option 66 and 67 in my two DHCPs like this:

Option 66 = 192.168.3.93
Option 67 = ipxe.efi

Could you please help me ? I’ve been stuck on this issue for over 24 hours…

Thanx !

[george1421]

@Faurel There are several things here.

The no valid offer received, indicates it either did not receive a dhcp packet without the next server and boot file listed or what it was given didn’t satisfy the request.

Let start with something that jumped out at me first. The pxe booting computer is being issued an 192.168.10.72 IP address (this is good so we know its receiving a reply). And your FOG server is on 192.168.3.93. That tells me they are on different subnets or you have a pretty wide network mask. Are these two devices on the same subnet?

If they are on different subnets, what is the dhcp server the workstation subnet? Is it possible you don’t have the pxe booting values set in the scope for the workstations? Or there is another dhcp server in play here?

Also make sure you don’t have white spaces around your dhcp option values I’ve seen a trailing white space on a parameter mess up dhcp too.

Lastly what device manufacturer and model is your dhcp server? Some SoHo routers will point dhcp option 66 to them even if there is a valid dhcp option 66 activated, but I don’t think that is the case here because the client is complaining about not getting any valid offers. Also on your dhcp sever make sure it issues both bootp (older) and dhcp (current) pxe booting values. These are kept in two different places in the dhcp server’s response packet.

[Faurel]

This post is deleted!

[Faurel]

@george1421 Hi,

Thank you very much for your reply.

I’m sorry for the delay : I haven’t been working these last few days.

The two devices are indeed on two separate subnets, but everything is configured correctly in DHCP for these networks to communicate. Furthermore, options 66 and 67 have been configured correctly on both subnets.

I can confirm that there are no spaces around my DHCP values.

My DHCP server is a VM running Nutanix.

About your last part “make sure it issues both bootp (older) and dhcp (current) pxe booting values. These are kept in two different places in the dhcp server’s response packet”, how can i do that ?

Thank you again for your time.

[george1421]

@Faurel said in PXE over IPv4:

My DHCP server is a VM running Nutanix.

What is your dhcp server? Is it MS Windows based or something else.

Do you know how to run wireshark? I think we need to get a witness computer (a third computer not part of pxe booting). Place the wireshark computer on the same subnet as the pxe booting computer. Use the capture filter of port 67 or port 68 This capture filter will only collect pxe booting information.

What I want to focus on is the one or more DHCP OFFER packets.

1. Is there more than 1 OFFER packet?
2. Is the OFFER packet from the correct DHCP server?
3. Looking into the OFFER packet, in the packet header there are two fields one called {next-server} and {boot-file} are these fields populated?
4. Look at the dhcp options do you see options 66 and 67? Do they point to the correct values?

If you are unsure of what you are looking at, upload the file to a file share site and post the link here and I will take a look for the common issues.

[Faurel]

@george1421
I’m sorry, my DHCP is MS Windows based (Windows Server 2022 DC).

Here the picture, i’m not sure it’s wat you was looking for ?

It was the only DHCP field that i had while i was trying to boot over PXE on my MS Surface.

Thx

[george1421]

@Faurel ok good that looks like a clean dhcp process. It would be helpful to have the pcap file in my hand, but you want to expand the OFFER packet. The OFFER packet you can tell from the Info column.

In the packet you may need to expand the dhcp section. You should see the image similar to below. What is important is the next server IP address should point to IP address of your fog server. and boot file name should be ipxe.efi. You see in this example that the boot file name was not given, this is the error with this packet. The next server and boot file are in the ethernet header. This is the legacy bootp pxe section.

The next place you need to check is the dhcp options below. You should see dhcp options 66 which should be the IP address of the fog server and dhcp 67 should be the boot file name of ipxe.efi. In this picture this packet is also in error since the dhcp server is not sending out all of the pxe booting info. So if your offer packet looks like this you have a problem.