[Dnsmasq-discuss] Referring the PXE GUID / UUID in dhcp script

Simon Kelley simon at thekelleys.org.uk
Tue Mar 5 17:14:35 GMT 2019


On 20/02/2019 06:38, 西谷優希 wrote:
> Hi,
> 
> http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2010q1/003844.html
> As mentioned in this post, a PXE request contains a GUID / UUID value.
> Is there a way to refer this GUID / UUID in dhcp script?
> 
> I'd like to implement like below:
> 1. execute PXE Boot
> 2. send DHCP request to dhsmasq
> 3. hook dhcp-script which does:
>   - refer UUID of the client
>   - take the the client information from CMDB
>   - create pxelinux.cfg/<UUID> with the taken information(e.g. RAID
> type, kernel version)
> 4. send DHCP response to the host
> 5. booting goes on ...
> 
> Of course, it is possible to use the MAC address of NIC in place of
> UUID, but it can be changed by repair and replacement and the priority
> of UUID is higher than the MAC address of NIC for pxelinux.
> So it's great if GUID / UUID can be referred in dhcp script.
> 
> Thanks,
> nishitani yuki
> 
> _______________________________________________

There are two problems with this idea.

1) The UUID is not supplied to the script (but that's easy to fix.)

2) The script execution is asynchronous. The DHCP protocol processing
doesn't wait for the script to execute, so you will have a big fat race
condition where the host may actually be booting before or after step 3
above has occurred.

Cheers,

Simon.




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