Poll: All DHCP options in script are usefull?
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Agree, please build it. 0% 0 0%
Not usefull at all. 100.00% 1 100.00%
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DHCP command incomplete
2011-12-20, 19:08
Post: #1
DHCP command incomplete
Hi, i found that ipxe when using dhcp in a script does reject all dhcp-options that are not used by ipxe. My request is that it does not reject them because you can make good use of them in script. Let me give an example:

#!ipxe
dhcp
isset ${224} && ${224}
autoboot

This script does not work because option 224 is rejected by ipxe. If it would not be rejected it would do:
1 a dhcp request
2 when option 224 would contain a valid command it would execute this command.
3 when there is nothing in option 224 it would autoboot.

You can test my idea by replacing ${224} with ${initiator-iqn} and put something usefull in your dhcp server sanboot string option like "chain http://myserver/boot.php". Only thing is we don't want to use ${initiator-iqn} for this but some user defined options (224 to 254).

So my idea is when you do a dhcp request make sure ALL (0-255) the dhcp-options you get from the dhcp server are available in script.
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2011-12-20, 20:25
Post: #2
RE: DHCP command incomplete
(2011-12-20 19:08)lstraath Wrote:  #!ipxe
dhcp
isset ${224} && ${224}
autoboot

This script does not work because option 224 is rejected by ipxe. If it would not be rejected it would do:
1 a dhcp request
2 when option 224 would contain a valid command it would execute this command.
3 when there is nothing in option 224 it would autoboot.

You can test my idea by replacing ${224} with ${initiator-iqn} and put something usefull in your dhcp server sanboot string option like "chain http://myserver/boot.php". Only thing is we don't want to use ${initiator-iqn} for this but some user defined options (224 to 254).

So my idea is when you do a dhcp request make sure ALL (0-255) the dhcp-options you get from the dhcp server are available in script.

All options provided by the DHCP server are made available to the script. You need to configure your DHCP server to override the DHCP parameter request list to force the DHCP server to hand out your custom option 224 (which will not be requested by iPXE). For ISC DHCPD, look up the documentation for "option dhcp-parameter-request-list".

Michael
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2011-12-21, 07:33 (This post was last modified: 2011-12-21 07:47 by lstraath.)
Post: #3
RE: DHCP command incomplete
I do not have the DHCP server you mention but i have the latest pfSense release where you can add every option you want in the gui. I added 224 however when i do something like this i see nothing.

#!ipxe
dhcp
echo ${224}

[Image: dhcp-options.png]

The URL in the note is the following page:
http://www.iana.org/assignments/bootp-dh...meters.xml

You talk about not requested by ipxe, would it be an idea to implement a switch for that? Something like: dhcp /all
The reason i ask is i can fill al the options i want in pfSense or any other DHCP server but i do not know i want to force the options because every dhcp package will grow maybe i only want to have everything exclusively for ipxe.
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