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Defining new DHCP options

Link to this post 07 Aug 10

Hello,

I am trying to send out some created DHCP options.
I set up a dhcp3-server on an ubuntu 10.04. I did what is written in man dhcp-options. Namely, i tried to add following lines in dhcpd.conf :

option myoption code 194 = text;
option myoption "helloworld";

I obviously use some casual values for the test.

Then, i edited /etc/dhcp3/dhclient.conf on the client side so that the latter be able to receive the defined option.

My client ask for that option (194) as we can see on the following screenshot :
http://img138.imageshack.us/img138/5197/listeoptions.png

Then, the server send that option :
http://img265.imageshack.us/img265/5784/definedoption.png

However, i don't manage to use the content in a shell script, i think i should do it since

I looked at /etc/dhcp3/dhclient-exit-hooks.d/debug
As it's written in this script, by setting a value on 'yes' we can see different variable used in /sbin/dhcp-script. but my defined option didnt appeared. Indeed, the variable should be $new_myoption (but it doesn't work in /sbin/dhcp-script), i got following lines :

Mon Jun 28 22:42:47 CEST 2010: entering dhclient-enter-hooks.d, dumping variables.
reason='REBOOT'
interface='eth0'
medium=''
alias_ip_address=''
new_ip_address='192.168.2.60'
new_subnet_mask='255.255.255.0'
new_domain_name='test.org'
new_domain_search=''
new_domain_name_servers=''
new_routers='192.168.2.254'
new_static_routes=''
old_ip_address=''
old_subnet_mask=''
old_domain_name=''
old_domain_search=''
old_domain_name_servers=''
old_routers=''
old_static_routes=''
--------------------------
Mon Jun 28 22:42:47 CEST 2010: entering dhclient-exit-hooks.d, dumping variables.
reason='REBOOT'
interface='eth0'
medium=''
alias_ip_address=''
new_ip_address='192.168.2.60'
new_subnet_mask='255.255.255.0'
new_domain_name='test.org'
new_domain_search=''
new_domain_name_servers=''
new_routers='192.168.2.254'
new_static_routes=''
old_ip_address=''
old_subnet_mask=''
old_domain_name=''
old_domain_search=''
old_domain_name_servers=''
old_routers=''
old_static_routes=''
-------------------------

So how could i get access to my defined option ?

Thanks
Regards

Link to this post 08 Aug 10

The actions you are taking are definitely new to me, but knowledge of the potential of hooks has inspired me to do some testing. By what I can see it looks like you specified options are necessary in you both your dhcpd.conf and dhcpcd.conf files, in addition it you want some actions to be taken based upon the contents of the additional options then you need to create a script to evaluate the new option in /lib/dhcpcd/dhcpcd-hooks directory.

Please correct me if you understanding is incorrect because I would really like to work through this with you to see how I can use the dhcpd hooks to trigger synchronization events.

Link to this post 11 Aug 10

I installed dhcp3-server and i just have a directory in /etc/dhcp3 which contain
dhclient.conf
dhclient-enter-hooks.d
dhclient-exit-hooks.d
dhcpd.conf

I have no dhcpcd. What are you talking about ?

Link to this post 12 Aug 10

dhcpd.conf is the server configuration file and dhcpcd.conf is the client configuration file. By what I have read you must update the clients to know how to handle the new flag.

On the same note I will be testing various dhcpd options and custom flags in a virtual instance so I can better assist, but since I will be going on vacation so it may take a couple of weeks before I post a guide and tutorial on my Linux.com blog about my findings.

Link to this post 23 Aug 10

hey,
My client configuration file is /etc/dhcp3/dhcliennt.conf.
I am looking forward to hear about your tests.

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