How does DHCPD determine what IP address to assign and...
Ryan McCain
Ryan.McCain at dss.state.la.us
Fri Dec 21 21:07:39 UTC 2007
I might have figured it out. Unfortunately there is no one here to test due to the holidays:
class "DialUp" {
match if substring(option vendor-class-identifier, 0, 9) = "ASYNC";
log (info, " Matched Dialup Rule");
}
subnet 10.116.6.0 netmask 255.255.255.0 {
pool {
allow members of "DialUp";
range 10.116.6.1 10.116.6.8;
option routers 10.116.6.1;
}
}
<SNIP>
#VPN
subnet 10.116.6.0 netmask 255.255.255.0 {
range 10.116.6.9 10.116.6.179 ;
option routers 10.116.6.1;
...
..Will this reserve IP addresses 10.116.6.1 - 10.116.6.8 for DHCP clients with a UID that contains ASYNC?
>>> On Fri, Dec 21, 2007 at 2:46 PM, in message
<476BD1DB.5D1A.003A.0 at dss.state.la.us>, "Ryan McCain"
<Ryan.McCain at dss.state.la.us> wrote:
> I found a few posts in the archives but am a bit confused. I don't know what
> the 0 and 9 are for and used the example I found as a template. I am on the
> right track if I want all DHCP clients that connect w/ the UID containing
> ASYNC be assigned IP addresses between 10.120.5.100-108 only??
>
>
> class "DialUp" {
> match if substring(option vendor-class-identifier, 0, 9) = "ASYNC";
> log (info, " Matched Dialup Rule");
> range 10.120.5.100 10.120.5.108
> }
>
> ..Thanks..
>
>>>> On Fri, Dec 21, 2007 at 12:40 PM, in message
> <a06240822c391b86b364d at simon.thehobsons.co.uk>, Simon Hobson
> <dhcp1 at thehobsons.co.uk> wrote:
>> Ryan McCain wrote:
>>
>>>1) If I have a defined scope of 10.120.5.1 - 10.120.5.180, whill
>>>DHCPD hand out .1 to the first DHCPD client, .2 to the second and so
>>>on? Or is there another algorithm thats used?
>>
>> No, officially the initial order is undefined - in practice, the
>> current implementation will allocate unused leases from the highest
>> address down for no other reason than the way they are hashed
>> internally.
>>
>> Once there are no "never used before" addresses left, addresses are
>> recovered from expired leases on a least recently used basis.
>>
>>>2) Is it possible to assign a subset of IP addresses in my scope to
>>>DHCP clients whos UID identifier contains a specific string? For
>>>example, all dialup users have ASYNC in their UID. We'd like to be
>>>able to assign them IP addresses 10.120.5.100 - .180.
>>
>> Yes, see the list archives, and 'man dhcpd.conf' looking for classes
>> and subclasses.
>>
>> Very briefly, you define a class which matches on some criteria (such
>> as the UID starting with ASYNC), then define a pool and only allow
>> members of the class to use that pool.
More information about the dhcp-users
mailing list