DHCP config
Glenn Satchell
Glenn.Satchell at uniq.com.au
Mon Jun 25 16:13:11 UTC 2007
man dhcp-eval
...
substring (data-expr, offset, length)
The substring operator evaluates the data expression and
returns the substring of the result of that evaluation
that starts offset bytes from the beginning, continuing
for length bytes. Offset and length are both numeric
expressions.
...
hardware
The hardware operator returns a data string whose first
element is the type of network interface indicated in
packet being considered, and whose subsequent elements are
client's link-layer address. If there is no packet, or
if the RFC2131 hlen field is invalid, then the result is
null. Hardware types include ethernet (1), token-ring
(6), and fddi (8). Hardware types are specified by the
IETF, and details on how the type numbers are defined can
be found in RFC2131 (in the ISC DHCP distribution, this is
included in the doc/ subdirectory).
So the hardware operator returns 01:00:02:02:x:y:z for your ethernet
devices. You can match on either
substring( hardware, 0, 4 ) = 01:00:02:02;
or
substring( hardware, 1, 3 ) = 00:02:02;
regards,
-glenn
>From: "Gideon Viator" <ktcisg at kaplantel.net>
>
>Sry guys,
>
>Should I put a 1 or 0 after hardware?
>
>Gideon Viator
>IT Administrator
>Kaplan Telecommunications
>337-643-7171
>
>
>
>-----Original Message-----
>From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On Behalf
>Of Bruce Hudson
>Sent: Monday, June 25, 2007 10:30 AM
>To: dhcp-users at isc.org
>Subject: Re: DHCP config
>
>
>> class "amino" {
>> match if substring( hardware, 0, 3 ) = 00:02:02;
>> }
>
> If I recall correctly, you want "substring( hardware, 1, 3 )". You want
>to skip the first byte of the hardware field, which is a "1" to specify an
>ethernet address.
>--
>Bruce A. Hudson | Bruce.Hudson at Dal.CA
>UCIS, Networks and Systems |
>Dalhousie University |
>Halifax, Nova Scotia, Canada | (902) 494-3405
>
>
>
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