DHCPOFFER rejected by rule

Bjørn Mork bjorn at mork.no
Fri Jul 10 07:42:52 UTC 2020

Matthew Butch <apple4ever at me.com> writes:

> Here is an issue I can't figure out. I've search to no avail.
> I have ISC DHCP running on one server ( and a Cisco switch
> acting as a DHCP relay across VLANs.
> dhclient on Ubuntu 16.04 is reporting DHCPOFFER from
> rejected by rule mask
> Yet there is no reject command in the list. Where is this coming from
> and how do I fix?

This can be caused by issues with the dhcp client option request
config.  See for example


These are related to NetworkManager generated dhclient configs, but the
underlying issue is applicable to any dhclient config with buggy
"request" lines.


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