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Is it possible for MacOS X (current version or in any previous one) to easily force DHCP client to send to DHCP server, at the beggining of the conversation - in DHCPDISCOVER packet - option "Vendor Class Identifier" (60) set to some value?

I know that I can install i.e. ISC DHCP client through pkgsrc which supports VCI, but I'm looking for something native.

Thank you in advance for information.

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2 Answers 2

up vote 3 down vote accepted

This rather old wiki post indicates that Mac OS X does send a VCI of AAPLBSDPC plus some other info about the processor and machine type back to the server. However, I'm not having any luck finding any info on how you would actually change that value on the client. I think your only option may be to run a different client.

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Yeah. Thanks at least for this. I've just confirmed this with Apple support - it is not possible. Thanks again. –  plluksie Jan 12 '11 at 16:13

I spent a solid hour on the phone with Apple support, and they just don't get DHCP at all. You will eventually get the "we don't provide support for anything that you can't access and configure through the GUI. You're on your own, mate." if you keep probing them. Of course, I had one "genius" tech try to tell me that the VCI was set by the MAC address and that it couldn't be changed. I then proceeded to tell him what an ignorant ass he was.. explained what the OUI of the MAC is and why it exists, how it relates to dhcp client-identifier and how it has NOTHING to do with the dhcp vendor-class-identifier. In the end, he apologized for being a cocky ass and trying to just push me off the phone and thanked me for giving him an education.. but still no resolution.

It appears that, like M$ Windoze, the VCI on a Mac is locked up in a binary somewhere and you simply can't change it.

My workaround for this problem was:

  1. Download and install the XCODE compiler from the Mac Developer site.
  2. Download, compile and install the latest ISC DHCP package.
  3. Tweak the dhclient.conf file to include the following send vendor-class-identifier "MSFT 5.0";
  4. ..and enjoy.

The whole operation took 35 minutes, most of which was spent watching the packages download. My machine works a treat now. No more issues with DHCP working for XP boxes and not my MBP. Don't be afraid of the ISC client. It works just fine, and doesn't conflict with the built-in client.

J

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Thanks for the suggestion. I also considered compiling isc dhcpd using netbsd's pkgsrc and distributing this via packages.Anyway, problem is in fact that this have to be deployed on >500 devices. And process of providing proper DHCP wrapper which will switch between native dhcp client and isc's, takes more time than it is needed. BTW. at the beggining of my discussion with support I stated that Vendor Class Identifier =/= Dhcp Client Identifier and this saved me some time ;) –  plluksie Mar 17 '11 at 12:38

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