Cisco FTD 2100 capture DHCP packets on Client Nodes subnet, DHCP Relay

red2play — Mon, 06 May 2024 17:29:27 GMT

I've configured DHCP relay on the FTD and I have a 2nd FTD as a backup default gateway. x.x.x.1 and x.x.x.2 respectively. However something is wrong. When I enabled DHCP relay on the .1 FTD only, the DHCP relay wouldn't work and then I enabled this on the .2 FTD, it now works. I want to know why its not working w/ the .1 FTD. I realize that its probably an access-list issue and I can probably just mirror the configuration from the .2 to the .1 but I really want to troubleshoot the issue, not just get it to work.

I've enabled WireShark on the client and I can see the initial DHCP Discover packets was going out. I realize that there are some ancillary data that I can collect but to just see the packets reach the FTD interface and see the FTD process kick in is important to me. Its a premier FW and I should be able to see the FW process the DHCP packets.

I'm aware that the DHCP process (DORA) in the discovery phase lists the source as 0.0.0.0:67 and the destination as 255.255.255.255:68. Is there a way to capture DHCP packets for troubleshooting purposes?

Re: Cisco FTD 2100 capture DHCP packets on Client Nodes subnet, DHCP R

MHM Cisco World — Mon, 06 May 2024 17:40:27 GMT

You config both FTD in ip helper-address?

If yes

Then

In each ftd do

Capture dhcp interface <name of interfaces connect to host> match ip host <ip of interfaces under which you config helper address> host <ip of ftdi nterface >

MHM

topic Cisco FTD 2100 capture DHCP packets on Client Nodes subnet, DHCP Relay in Network Security

Cisco FTD 2100 capture DHCP packets on Client Nodes subnet, DHCP Relay

Re: Cisco FTD 2100 capture DHCP packets on Client Nodes subnet, DHCP R