Server Move...

Keith Woodworth kwoody at
Wed Oct 18 02:56:50 UTC 2006

On Sun, 15 Oct 2006, Glenn Satchell wrote:

|->>Figured it was just as easy to start out with a fresh lease file.
|->You can copy the whole lease file across. When the dhcp server
|->starts and reads the lease file it will discard any leases for subnets
|->it doesn't know about. Likewise it will take the latest version of any
|->lease, so multiple lease entries will also be handled. It should be as
|->simple as just copying over the whole file and appending it to whatever
|->lease file you have on the new server.
|->In a similar move, when you delete the subnet definition on the old
|->server and restart dhcp it will also delete all the leases it had for
|->the old subnet.
|->So the next time you migrate a subnet you can append the whole lease
|->file from the old server and it will sort itself out.

Hi Glenn.

So basically when ready to switch, stop the old server, copy the old lease
file to the new server, stop the new server, do a:

cat old.server.dhcpd.leases >> dhcpd.leases

make sure the new subnet is in the new dhcpd.conf file, start the new
server then change the dhcp relay (ip helper) and things will just work?

Sounds too easy...!

One question arises from that. One of the dhcp servers that is being
retired is still running dhcpd 2.0.

There is a bit of a diff between 2.0 and version 3.0.4 the new
server is running with regards to the lease file:


lease {
        starts 3 2006/10/18 02:43:34;
        ends 3 2006/10/18 03:13:34;
        hardware ethernet 00:00:39:53:1f:e4;
        uid 01:00:00:39:53:1f:e4;
        client-hostname "J1";


lease {
  starts 3 2006/10/18 02:44:19;
  ends 3 2006/10/25 02:44:19;
  binding state active;
  next binding state free;
  hardware ethernet 00:11:11:a2:78:a9;
  uid "\001\000\021\021\242x\251";
  client-hostname "the-aac2ad07137";

Will v3 of dhcpd be able to hand that ok?


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