Multi IP assign for single MAC-Urgent

arun.sasi1 at arun.sasi1 at
Mon Jan 3 12:36:23 UTC 2011

Ho to implement below in my Ubuntu server.

if { substring (client-id,1,4)="RAS "
    ignore booting ;

-----Original Message-----
From: at
[ at] On Behalf
Of Simon Hobson
Sent: Monday, January 03, 2011 6:02 PM
To: Users of ISC DHCP
Subject: Re: Multi IP assign for single MAC-Urgent
Importance: High

arun.sasi1 at wrote:

>This is a multi IP assignment for single host with DHCP server.
>I have dhcp server running in Ubuntu platform. I have configured 
>DHCP with "range". There is no MAC binding or reserve concept.
>Here I can see in my Webmin and database multiple active 
>IP for single host.
>I compared the two active lease and found that client are populating 
>and registered with two different UID for single MAC.
>Please help me to resolve this issue.

Did you try searching the archives at all - it's a common and well 
known problem.

>lease {
>   starts 3 2010/12/29 06:01:26;
>   ends 4 2010/12/30 06:01:26;
>   tstp 4 2010/12/30 06:01:26;
>   cltt 3 2010/12/29 06:01:26;
>   binding state active;
>   next binding state free;
>   hardware ethernet e0:cb:4e:24:8c:27;
>   uid "\001\340\313N$\214'";
>   client-hostname "MHAMZEHNAZ-IR16";
>lease {
>   starts 2 2010/12/28 04:32:34;
>   ends 5 2010/12/31 04:32:34;
>   tstp 5 2010/12/31 04:32:34;
>   cltt 2 2010/12/28 04:32:34;
>   binding state active;
>   next binding state free;
>   hardware ethernet e0:cb:4e:24:8c:27;
>   uid "\001RAS \340\313N$\214'\000\000\000\000\000\000";
>   client-hostname "MHAMZEHNAZ-IR16";

The key bit here is the uid starting with ""\001RAS ", which suggests 
this is a Windows server with RAS (Remote Access Service) enabled. 
These servers will automatically obtain (IIRC) 10 addresses just in 
case a client should ever connect to it. If you aren't using RAS, 
then the easiest thing to do is to ignore such requests like this :

if { substring (client-id,1,4)="RAS "
    ignore booting ;

See also :
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