What Exactly Causes "uid lease" Messages?
Martin McCormick
martin at dc.cis.okstate.edu
Sun Jun 15 02:39:06 UTC 2008
Claus Holm Christensen writes:
> In DHCP, the client is supposed to send both a MAC address and a DHCP
> Client Identifier (called "uid" in the leases file?) to the server, to
> identify the client. The DHCP server should prefer this value over the
> MAC address, but when two hosts on different networks share the Client
> Identifier, the server realises that it can't possibly be the same host
> and emits this error message to warn about it.
>
> It should be easy to find out. Check the leases-file and locate the two
> different leases mentioned, then compare the uid field.
I did and it is like you describe except for 1 thing.
After picking one at random, I found three leases with the same
UID. They also had the same MAC address. How folks are doing
this I am not sure, but it is as if they have a previous fond
memory of X lease which they sometimes ask for.:-)
Here is the pair of leases for one client. The hardware
address is the same as well as the UID field.
lease 139.78.228.141 {
starts 5 2008/06/13 06:07:10;
ends 5 2008/06/13 06:37:10;
tstp 5 2008/06/13 06:37:10;
tsfp 5 2008/06/13 07:22:10;
atsfp 5 2008/06/13 07:22:10;
cltt 5 2008/06/13 06:07:10;
binding state free;
hardware ethernet 00:15:c5:ac:bd:87;
lease 139.78.228.230 {
starts 0 2008/06/15 01:16:20;
ends 0 2008/06/15 01:46:20;
tstp 0 2008/06/15 01:46:20;
tsfp 0 2008/06/15 02:31:20;
atsfp 0 2008/06/15 02:31:20;
cltt 0 2008/06/15 01:16:20;
binding state free;
hardware ethernet 00:15:c5:ac:bd:87;
lease 139.78.231.94 {
starts 4 2008/06/12 10:12:41;
ends 2 2008/05/27 17:22:38;
tstp 4 2008/06/12 10:12:41;
tsfp 4 2008/06/12 10:12:41;
atsfp 4 2008/06/12 10:12:41;
cltt 2 2008/05/27 16:52:38;
binding state backup;
hardware ethernet 00:15:c5:ac:bd:87;
lease 139.78.231.177 {
starts 4 2008/06/12 02:33:31;
ends 4 2008/06/12 02:35:31;
tstp 1 2008/04/14 10:15:45;
tsfp 4 2008/06/12 02:35:31;
atsfp 4 2008/06/12 02:35:31;
cltt 4 2008/06/12 02:33:31;
binding state backup;
hardware ethernet 00:15:c5:ac:bd:87;
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