not getting same ip for same MAC

Pavel Zhukov pzhukov at
Wed Aug 8 15:38:49 UTC 2018

You can add into your dhclient.conf following statement:
send dhcp-client-identifier = hardware;
On Wed, Aug 8, 2018 at 5:05 PM Christopher Barry
<christopher.r.barry at> wrote:
> configs and leases file here:
> Problem:
> I'm booting an embedded device via u-boot over tftp, and I am getting
> one IP during boot, and another IP once Linux comes up. This has not
> always done this, and I am struggling to find a solution.
> Scenario:
> I have a pool with 2 IPs in it, and I boot 2 devices in a test fixture.
> Each device position (regardless of physical device) always gets the
> same IP, as I am deleting the leases file / restarting dhcpd between
> invocations of the test, and I power on the devices in the same order.
> Now, device1 boots the tftp image, gets (as it should), then
> when Linux boots and requests an IP, it is getting (which it
> should NOT do). I have the lease time and max lease time set to 1 (but
> I have set these values to many other values up to a couple minutes
> with no change).
> To be clear, this has worked for over a year, and suddenly is not
> working. The Linux platform running dhcpd is centos 7. The dhcpd
> version is in the pastebin link above.
> In the leases file it can be seen that the uid value is different
> between u-boot and linux, even though the MAC is the same. I'm
> suspicious that this is what is confusing dhcpd.
> How can I MAKE it only use MAC?
> Thanks!
> --
> Regards,
> Christopher
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> dhcp-users at

Pavel Zhukov
Software Engineer
IRC: landgraf

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