Configuring option 82
Sten Carlsen
stenc at s-carlsen.dk
Fri Sep 27 13:37:10 UTC 2019
Looking at the web page, I see that he defines his classes inside the
subnet, this is bad advice, it will not do what you may want.
Classes are global wherever they are defined just as host statements.
They both inherit some things from the place of definition and use it
elsewhere to great frustration for the guy trying to debug this.
Place class and host definitions in the global scope, that causes least
problems.
On 27/09/2019 15.25, Bill Shirley wrote:
>
> Yeah, I had found that web page too. But note later on that page he
> states about his patch:
> This has been tested on a Xeon 2.8 Ghz server, it uses just a few
> percent of CPU with 40.000 DHCP clients.
> Do you have 40,000 clients?
>
> I use many classes in my DHCP configurations on 15+ servers. I
> haven't had a problem
> with DHCP eating up all the resources.
>
> What is you goal here? Are you wanting to assign a fixed address for
> each client?
>
> Bill
>
> On 9/27/2019 7:32 AM, Surya Teja wrote:
>> Hi Bill Thanks for reply
>> Why are you avoiding the class statement?
>> In one of the google forum I have read the statement saying like
>> The internal implementation in ISC DHCPD of classes is such that it
>> scales in a non-linar way - O(N^2) or something. So suddenly you'll
>> end up with dhcpd eating 100% CPU.
>> So I just want to avoid the classes
>> While surfing I found that for the host declaration statements we can
>> use the syntax like
>> EX: host client-name-1 {
>> *host-identifier option agent.circuit-id "dslam42.port22";*
>> hardware ethernet 00:e0:4c:a7:ca:de;
>> fixed-address 192.168.0.6;
>> }
>> So I just want to know any config statements similar like above
>> applies for scope sections
>>
>> What does the agent.circuit-id and agent.remote-id contain? I can't
>> figure out why you're using substring on these values (in your
>> original post).
>> It is just sample example I found in the forum, I don't have issue
>> with directly checking without using the substring function
>> or binary-to-ascii to cross check the values
>>
>> Thanks
>>
>>
>> On Fri, Sep 27, 2019 at 4:06 PM Bill Shirley
>> <bill at c3po.polymerindustries.biz
>> <mailto:bill at c3po.polymerindustries.biz>> wrote:
>>
>> Options in a pool are options to be *sent* not matched.
>>
>> Why are you avoiding the class statement? What does the
>> agent.circuit-id and agent.remote-id contain?
>> I can't figure out why you're using substring on these values (in
>> your original post).
>>
>> Bill
>>
>> On 9/27/2019 3:44 AM, Surya Teja wrote:
>>> Hi
>>> It might be too many questions but I wan to configure my dhcpd
>>> configuration file by avoiding the classes as much as possible
>>> If the subnet is configured as like below snippet
>>> subnet 192.168.10.0 netmask 255.255.255.0 {
>>> pool {
>>> range 192.168.10.10 192.168.10.199;
>>> option subnet-mask 255.255.255.0;
>>> option routers 10.1.10.1;
>>> option domain-name "test.com <http://test.com>";
>>> option agent.circuit-id "22";
>>> option agent.remote-id "192.168.10.242";
>>> }
>>> }
>>> can we achieve the option 82 configuration setup with above snippet
>>> Thanks in advance and or if any reference links to setup the
>>> option 82 functionality without class can also be appreciated
>>>
>>> On Thu, Sep 26, 2019 at 7:42 PM Surya Teja
>>> <suryateja042 at gmail.com <mailto:suryateja042 at gmail.com>> wrote:
>>>
>>> Hi is the option 82 supported by using class concept only ?
>>> or can it be defined as other general options like
>>> domain-name server, router in scope section ?
>>>
>>> On Tue, Sep 24, 2019 at 12:49 PM Surya Teja
>>> <suryateja042 at gmail.com <mailto:suryateja042 at gmail.com>> wrote:
>>>
>>> Hi,
>>> I am trying to configure the dhcp option 82, went
>>> through the google forums and one of it suggest the
>>> syntax like
>>> # vim /etc/dhcp/dhcpd.conf
>>> ########################################################
>>> log-facility local7;
>>> *class "VLAN10" {
>>> match if
>>> binary-to-ascii(10,16,"",substring(option
>>> agent.circuit-id,2,2)) = "10";
>>> } # VLAN10
>>> class "VLAN20" {
>>> match if ( substring(option
>>> agent.remote-id,2,15)="10.5.20.4"
>>> and binary-to-ascii(10, 16, "",substring(option
>>> agent.circuit-id, 4, 2)) = "2" );
>>> }*
>>> subnet 192.168.10.0 netmask 255.255.255.0 {
>>> pool {
>>> *allow members of "VLAN10";*
>>> default-lease-time 600;
>>> max-lease-time 7200;
>>> range
>>> 192.168.10.1 192.168.10.199;
>>> option routers
>>> 192.168.10.254;
>>> option broadcast-address
>>> 192.168.10.255;
>>> option subnet-mask
>>> 255.255.255.0;
>>> option domain-name-servers 4.2.2.2;
>>> }
>>> }
>>> subnet 192.168.20.0 netmask 255.255.255.0 {
>>> pool {
>>> *allow members of "VLAN20";*
>>> default-lease-time 600;
>>> max-lease-time 7200;
>>> range 192.168.20.20
>>> 192.168.20.199;
>>> option routers 192.168.20.254;
>>> option broadcast-address 192.168.20.255;
>>> option subnet-mask 255.255.255.0;
>>> option domain-name-servers 4.2.2.2;
>>>
>>> }
>>> (Just ignore ip values)
>>> can we configure this concept only by using classes and
>>> make it allow or deny like that?
>>> or can we use the option space concept to get it
>>> worked(do we have any other syntax). Thanks in advance
>>>
>>>
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