Gloeiende Oliebollen. I wanted to DHCP relay discovers MSGs off only ‘one’ specific device in my home network somewhere to the DHCP server on the other side of a GRE tunnel. Off course this is not really logical but that’s besides this post.
I installed ISC DHCP “yum install dhcp-4.1.1″. This packages comes with the ISC dhcrelay client which I figured to do the relaying. The Idea was to block all broadcast traffic designed for port 67 on this machine, and only to allow the specific MAC address.
When this was setup, I noticed all the local DHCP discovers/MAC’s passing the filter and thought I made a mistake. I did some troubleshooting and started with blocking individual MAC’s. This is normally an easy task by doing:”-A INPUT -m mac –mac-source 00:02:02:41:d0:77 -j DROP” and checking the hit counter of IPtables.
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