topic Need information on DHCP Relay in General Topics

Need information on DHCP Relay

scottoliver — Fri, 11 Jan 2019 00:04:36 GMT

Hello. To start I had a DHCP server configured on one of the interfaces on our Palo 810 PanOS 8.1.2. The DHCP addresses being handed out were not being registered with our DNS server so I was tasked to make that happen. I figured I would just set up DHCP relay instead. Unfortunatly I cannot get DHCP relay to work because of some setting on the DHCP server (windows 2012 r12). I am not sure what the setting is , but what is goig on is the DHCP server is trying to hand out the wrong subnet ip. It should be getting a 10.0.1.0/24 IP but instead its handing out 10.0.0.0/24 IP. So the palo is dropping the traffic because its the wrong IP.

ANyone know what option needs to be set on the DHCP server for this to work properly? Altertativly if anyone knows how to have the palo run the DHCP server as before but update our DNS server with the records that would be great as well. Please let me know if anyone has any ideas this is driving me bonkers.

Re: Need information on DHCP Relay

Mick_Ball — Fri, 11 Jan 2019 08:15:21 GMT

What is the scope on your dhcp, it will only give out what you allow it to....

also what is the address and subnet mask of the switch or device that is acting as an ip helper.(if you use one)

Re: Need information on DHCP Relay

OtakarKlier — Mon, 14 Jan 2019 17:02:54 GMT

Hello,

Along with configuring the relay, you need to have security policies in place to allow the traffic. Source from both zones as there is the 'request' and then the 'reply'.

i.e.

source destination application

dmz internal dhcp

internal dmz dhcp

Regards,