Duplicate lease, different ip.

Douglas Power dpower at fnb.co.za
Wed May 2 06:27:23 UTC 2007


Hi Bruce.

I changed my config as bellow:

authoritative;
ddns-update-style none;

shared-network ltspcc {
   option domain-name-servers 10.42.2.24;
   option domain-name "greenfields.fnb.co.za";
   filename "/lts/2.6.17.3-ltsp-1/pxelinux.0";
   next-server 10.42.200.5;
   default-lease-time 2592000;
   max-lease-time 2592000;
   option log-servers 10.42.200.5;
   option routers 10.42.201.1;

subnet 10.42.201.0 netmask 255.255.255.128 {
   option subnet-mask 255.255.255.128;
   #option option-128 code 128 = string;
   #option option-129 code 129 = text;
   option broadcast-address 10.42.201.127;
   deny duplicates;
   pool {
   deny dynamic bootp clients;
   option root-path "10.42.200.11:/opt/ltsp-4.2u2/i386";
   range 10.42.201.26 10.42.201.126;
   }
}
subnet 10.42.201.128 netmask 255.255.255.128 {
   option subnet-mask 255.255.255.128;
   option broadcast-address 10.42.201.255;
   deny duplicates;
   pool {
   deny dynamic bootp clients;
   option root-path "10.42.200.11:/opt/ltsp-4.2u2/i386";
   range 10.42.201.154 10.42.201.254;
   }
}
}


After clearing out the leases file and restarting dhcpd the same thing
happens with the duplicate IP address but if I then restart dhcpd it
cleans up the duplicate. Unfortunately this does not help me because I
have only booted 1 machine and I have 2 IP address used(as bellow).

 lease 10.42.201.125 {
  starts 3 2007/05/02 05:18:05;
  ends 5 2007/06/01 05:18:05;
  tstp 5 2007/06/01 05:18:05;
  binding state active;
  next binding state free;
  hardware ethernet 00:0b:db:63:02:e3;
}
lease 10.42.201.126 {
  starts 3 2007/05/02 05:18:16;
  ends 5 2007/06/01 05:18:16;
  tstp 5 2007/06/01 05:18:16;
  binding state active;
  next binding state free;
  hardware ethernet 00:0b:db:63:02:e3;
  uid "\001\000\013\333c\002\343";
}

Any ideas?

Thanks,

Doug.


On Mon, 2007-04-30 at 12:11 -0300, Bruce Hudson wrote:
>   
> > I have some strange things happening with my dhcp server.
> > I am running SLES 10 with isc-dhcpd-V3.0.3
> 
>     The difference between the two leases is that the first request does
> not include a client identifier and the second does. In theory, the first
> (without an identifier) should always get one address and the request with
> an identifier should alway get a second since it is a different client.
> 
>     However, the first time the server see a request with an identifier it
> will "upgrade" an existing lease for that client address that does not have
> one by adding it. The process is not reversible so any requests there-after
> without an idetifier are a different client. There was an ancient message
> to the list from Ted Lemon that called this "tragically unavoidable". 
> 
>     This doesn't really change anything in your case, except for which IP
> is kept in use. Setting up a host stanza with "deny duplicates" should take
> care of your problem. It tells the server to discard any existing leases
> for the specified hardware address, even if the client identifiers do not
> match.
> --
> Bruce A. Hudson				| Bruce.Hudson at Dal.CA
> UCIS, Networks and Systems		|
> Dalhousie University			|
> Halifax, Nova Scotia, Canada		| (902) 494-3405
> 
-- 
Douglas Power <dpower at fnb.co.za>
FNB

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