[SPAM] Re: [SPAM] Broadcast address leased to a client *Again*

Simon Hobson dhcp1 at thehobsons.co.uk
Wed Mar 17 19:07:44 UTC 2010

Daniel D. Gonçalves wrote:

>>However, there have been reports on this list 
>>in the past that some devices running bad code 
>>do "get it wrong" when presented with such an 
>>address/netmask - and if you have any such 
>>devices then you may want to exclude them from 
>>your pool (as others have described).

>Yes, and my problem is just with devices that do 
>not accept these IPs ending "0" and "255".
>The solution using multiple range statements 
>works, but I consider it very boring...

Boring is what network admin should be - 
excitement is stressful ;-) But you have 
confirmed that such devices still exist.

The only other ways I can think of are :

host "bad_device_name" {
   hardware ethernet aa:bb:cc:dd:ee:ff ;
   deny booting ;

or create a class that matches the vendor OUI and 
block all devices from the vendor until they fix 
their code :

class "bad-code" {
   match if substring(hardware,1,3)="aa:bb:cc" ;
   deny booting ;

That would keep the bad device off the network 
where it could be argued it belongs !

Or if you run a recent enough version, then you 
could create dummy reserved leases for all the .0 
and .255 addresses. Reserved leases are very much 
like regular leases, except that they are 
permanently tied to one client and never 
re-allocated. You get all the advantages of 
leases (status, dynamic DNS, etc) but with 
effectively fixed addresses. If you created dummy 
leases then that would prevent the addresses 
being leased to other clients.

To be honest, it's easier to just create split 
ranges. It might not look pretty, but it's only a 
one-off config.

>I would like something more practical, someone 
>able to create a patch to not use the IPs ending 
>"0" and "255" within a range ?

Well that would be adding cruft, but I suppose if 
someone offered a patch then it might be accepted.

Simon Hobson

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