Vendor Encapsulated Options Bug??
Glenn Satchell
glenn.satchell at uniq.com.au
Wed Dec 15 13:38:04 UTC 2010
On 12/15/10 06:56, Jiann-Ming Su wrote:
> Running dhcpd 3.0.5 which ships with CentOS/RH 5. When I try to use Vendor
> Encapsulated Options, something doesn't seem to work quite right.
>
> In the following configs, we're trying to pass Option 43 to Aruba AP's. The
> first config is what Aruba's docs suggests, and it works:
>
> option serverip code 43 = ip-address; # Aruba Master IP
> class "vendor-classes" {
> match option vendor-class-identifier;
> }
> subnet 192.168.246.0 netmask 255.255.255.0 {
> subclass "vendor-classes" "ArubaAP" {
> option vendor-class-identifier "ArubaAP";
> option serverip 10.10.15.180;
> }
> }
>
> The Option 43 portion of the DHCPOFFER packet is as follows:
>
> 2b 04 0a 0a 0f b4
>
> Option: (t=43,l=4) Vendor-Specific Information
> Option: (43) Vendor-Specific Information
> Length: 4
> Value: 0a0a0fb4
So that is a single option value, and it is not encapsulated.
> However, if I try to use the "option space" config, the result is a bit
> different:
>
> class "vendor-classes" {
> match option vendor-class-identifier;
> }
> option space ArubaAP;
> option ArubaAP.serverip code 43 = ip-address;
> subnet 192.168.246.0 netmask 255.255.255.0 {
> subclass "vendor-classes" "ArubaAP" {
> option vendor-class-identifier "ArubaAP";
> vendor-option-space ArubaAP;
> option ArubaAP.serverip 170.140.15.180;
> }
> }
>
> The Option 43 portion of this DHCPOFFER packet is:
>
> 2b 06 2b 04 0a 0a 0f b4
>
> Option: (t=43,l=6) Vendor-Specific Information
> Option: (43) Vendor-Specific Information
> Length: 6
> Value: 2b040a0a0fb4
The option space encapsulates the option inside another option. It is
possible to encapsulate multiple "sub-options" inside option 43 using
this method. If you look at the values you can see what is going on:
2b (43 decimal, option number)
06 (overall length of the option)
2b (43 sub-option number)
04 (length of the next suboption)
0a0a0fbf (ip address 10.10.15.180)
> Is this a bug in the "option space" config of vendor encapsulated options for
> 3.0.5? Or, am I not configuring dhcpd correctly? Thanks for any insights.
It's not a bug, option 43 can be used in two different ways, and you've
tried both of them.
This is taken from the dhcp-options man page:
option vendor-encapsulated-options string;
The vendor-encapsulated-options option can contain either
a single vendor-specific value or one or more vendor-
specific suboptions.
--
regards,
-glenn
--
Glenn Satchell | Miss 9: What do you
Uniq Advances Pty Ltd, Sydney Australia | do at work Dad?
mailto:glenn.satchell at uniq.com.au | Miss 6: He just
http://www.uniq.com.au tel:0409-458-580 | types random stuff.
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