Option 61 (Client ID) in DHCPOFFER

Laurent PROUFF lprouff at auchan.fr
Fri Nov 25 12:54:32 UTC 2011


Tested and I have same result (even asking the client to claim it).

I think, from my knowledge, that cid (opt 61) is only valuable for dhcp
server (why the client asks the server for things it already knows). Do you
have specials needs for doing this ?

One possible way could be to send back value via a private option (range
224-254) :

option cid-sent-back code 224 = string;
option cid-sent-back = option dhcp-client-identifier;
option dhcp-parameter-request-list 1,3,6,12,15,26,28,42,224;

regards,
laurent


2011/11/24 Dima Fadeyev <dima at scancom.es>

>  Thanks for your reply,
>
> I've included this line into my dhcpd.conf:
> option dhcp-parameter-request-list 1,3,6,12,15,26,28,42,61;
>
> As you can see, option 61 is included. However I still can't make dhcp
> server include the option 61 into dhcpoffer. This is how my dhcpdiscover
> and dhcpoffer packets look like right now:
>
> On 11/23/2011 08:21 PM, Laurent PROUFF wrote:
>   TIME: 16:00:11.283846
>     IP: > (00:d0:cb:cf:d0:ab) >  (Broadcast)
>     OP: 1 (BOOTPREQUEST)
>  HTYPE: 1 (Ethernet)
>   HLEN: 6
>   HOPS: 0
>    XID: 64217936
>   SECS: 0
>  FLAGS: 0
> CIADDR: 0.0.0.0
> YIADDR: 0.0.0.0
> SIADDR: 0.0.0.0
> GIADDR: 0.0.0.0
> CHADDR: 00:d0:cb:cf:d0:ab:00:00:00:00:00:00:00:00:00:00
>  SNAME: .
>  FNAME: .
> OPTION:  53 (  1) DHCP message type         1 (DHCPDISCOVER)
> OPTION:  61 (  7) Client-identifier         01:00:d0:cb:cf:d0:ab
> OPTION:  60 ( 11) Vendor class identifier   udhcp 1.9.2
> OPTION:  57 (  2) Maximum DHCP message size 576
> OPTION:  55 (  8) Parameter Request List      1 (Subnet mask)
>                                               3 (Routers)
>                                               6 (DNS server)
>                                              12 (Host name)
>                                              15 (Domainname)
>                                              26 (Interface MTU)
>                                              28 (Broadcast address)
>                                              42 (NTP servers)
>
> ---------------------------------------------------------------------------
>   TIME: 16:00:11.284036
>     IP: > (00:22:4d:38:37:27) >  (00:d0:cb:cf:d0:ab)
>     OP: 2 (BOOTPREPLY)
>  HTYPE: 1 (Ethernet)
>   HLEN: 6
>   HOPS: 0
>    XID: 64217936
>   SECS: 0
>  FLAGS: 0
> CIADDR: 0.0.0.0
> YIADDR: 10.0.0.154
> SIADDR: 0.0.0.0
> GIADDR: 0.0.0.0
> CHADDR: 00:d0:cb:cf:d0:ab:00:00:00:00:00:00:00:00:00:00
>  SNAME: .
>  FNAME: .
> OPTION:  53 (  1) DHCP message type         2 (DHCPOFFER)
> OPTION:  54 (  4) Server identifier         10.0.0.32
> OPTION:  51 (  4) IP address leasetime      340600 (3d22h36m40s)
> OPTION:   1 (  4) Subnet mask               255.255.255.0
> OPTION:   3 (  4) Routers                   10.0.0.2
> OPTION:   6 (  8) DNS server                10.0.0.2,8.8.8.8
> OPTION:  12 (  7) Host name                 foobar2
> OPTION:  15 ( 11) Domainname                example.com
> OPTION:  26 (  2) Interface MTU             1500
> OPTION:  28 (  4) Broadcast address         10.0.0.255
> OPTION:  42 (  4) NTP servers               10.0.0.32
>
> Best regards,
> Dima Fadeyev
>
> hello,
>
>   maybe it can help.... (from man dhcp-options)
>
>  *option dhcp-parameter-request-list* *uint16* [*,* *uint16*... ]*;* This
> option, when sent by the client, specifies which options the client wishes
> the server to return. Normally, in the ISC DHCP client, this is done
> using the *request* statement. If this option is not specified by the
> client, the DHCP server will normally return every option that is valid in
> scope and that fits into the reply. When this option is specified on the
> server, the server returns the specified options. This can be used to force
> a client to take options that it hasn't requested, and it can also be used
> to tailor the response of the DHCP server for clients that may need a more
> limited set of options than those the server would normally return.
>  regards, laurent
>
> 2011/11/23 Dima Fadeyev <dima at scancom.es>
>
>> Hello everyone,
>>
>> I have a quick question. Is it possible to make ISC dhcpd server insert
>> the option 61 (client id) in DHCPOFFER, in case if it is present in
>> DHCPDISCOVER?
>> The ISC dhcpd version we are using is dhcp-4.1.1
>> (dhcp-4.1.1-12.P1.el6_0.4.x86_64 CentOS rpm).
>>
>> Thanks in advance
>>
>> --
>> Dima Fadeyev
>>
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>> dhcp-users mailing list
>> dhcp-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>
>
>
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