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I am in a situation where I do not have control over DHCP on a subnet. I have a Satellite server that I want to use to provision VMware guests. The Satellite is on a different subnet and VLAN.

Is there a way I can modify the guest's boot options so that PXE doesn't need DHCP? I just want to tell it what its IP configuration is, like "virtual DHCP", and TFTP location is in the guest configuration.

I have very little control over the vSphere environment either. I have just enough access to provision a guest. The subnet is shared with other guests that have their own DHCP requirements that supersede mine.

xdfil
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3 Answers3

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PXE (Booting from the net) always uses DHCP.

But you have alternatives for your problem: Even when you have no control over the DHCP server you can surely add a proxyDHCP server. In such environment when a PXE client boots it'll get offers from both; the regular DHCP server "and" the proxyDHCP server. From the first one it'll get the common net parameters (IP/Mask/etc) and from the second one it'll get the PXE specific stuff (TFTP server IP, and NBP filename). Using a proxyDHCP is not intrusive; it only answers to PXE clients DHCP requests. i.e. Serva is a PXE server that includes a proxyDHCP server. (I'm related to Serva development)

Pat
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  • serva is a pxe server. Its in section 1.5.1 of the spec. There are a lot of dhcp proxies (plane, Microsoft WDS) but the question is about doing it without DHCP. This solution requires not 1 but 2 separate dhcp servers. It's like asking for vegetarian sub but getting double pastrami with a side of bacon! At least you admitted you had an agenda. – Jim B Jun 27 '15 at 05:07
  • your concepts are not really correct. DHCP is an RFC standard, PXE is an industry standard, proxyDHCP is a protocol defined within the PXE standard. Then PXE, DHCP, and proxyDHCP are not the same. Serva is a DHCP server, a proxyDHCP, a PXE server, an HTTP Server, etc etc. The OP wants to PXE boot without DHCP services what is not possible; this answer gives him an alternative for using PXE w/o touching his already in place DHCP infrastructure. This solution DOES NOT require 2 DHCP servers. I encourage you to read the standards. I do not have any agenda. – Pat Jun 27 '15 at 08:43
  • Read the standards? I would strongly urge you to take a peek yourself. Pxe is not an industry standard its an INTEL standard. A PXE server is a DHCP server responding to the DHCP offer request on port 4011. If your product doesn't respind to DHCP offers on 4011, please expand on how your pxe server functions. This answer does not have a solution that doesn't involve DHCP, and point of fact, as you've stated now twice, does involve another DHCP solution. – Jim B Jun 30 '15 at 20:33
  • You are wrong... PXE IT IS an industry standard, Intel is highly involved but is not the only company. A PXE server is not a DHCP server responding on port 4011; you can perfectly have PXE services without any traffic on port 4011. only proxyDHCP services uses port 4011. You are mixing all the concept because you do not know the protocols. I encourage you (again) please read the standards. – Pat Jun 30 '15 at 21:38
  • The specs were written by Intel with input from system works, the standards (which I linked to in my answer) are on an Intel server. Is there some other standard you refer to? – Jim B Jul 01 '15 at 15:40
  • I'm referring to the same document you quoted; the difference between you and I is that I know the content of the document and the surrounding ecosystem; you do not. Instead of getting upset just read the documents and and please stop saying things like i.e. `PXE is DHCP`... – Pat Jul 01 '15 at 18:47
  • Pxe is DHCP. That was the intent when the doc was written and I am extremely familiar with some of the team that started on this in 98, that wrote it. Stop trying to changes the fact that DHCP is specifically and intentionally mentioned in the document as to the protocol used by and required for PXE. – Jim B Jul 01 '15 at 22:58
  • Pat, please don't abuse mod flags to attempt to control opposing views you don't like or agree with. Also, if you really need, please continue this discussion in chat. @JimB – Sven Jul 02 '15 at 13:00
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Use gPXE from http://etherboot.org/wiki/index.php

You can download a bootable ISO or floppy image to boot the VM from. I have used it for machines that werent able to network boot.

From gPXE you can then boot the same way PXE normally would - by loading a file from the TFTP server.

Exactly how you boot it depends on what your PXE server is running. Their wiki has plenty of howtos with examples for typical situations.

Grant
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  • Why the downvote? gpxe works, and seems to fit the questions requirements – Grant Jun 30 '15 at 04:16
  • I upvoted, seems exactly what the OP wanted as it provides a virtual ROM that can have a script attached. – Jim B Jul 02 '15 at 16:42
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PXE is DHCP. http://download.intel.com/design/archives/wfm/downloads/pxespec.pdf Pxe is dhcp discover packets with option 60 set as client, and only responds to a dhcp offer with option 60

Jim B
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  • I should have clarified I am referring to the PXE device, virtual device in this case, versus the protocol. I don't see why you couldn't pre-load some values into it and have the virtual device skip the first few stages of discovery. I've heard of less useful features before. – xdfil Jun 26 '15 at 06:08