I missed a sequence diagram for DHCP which not only shows the four basic messages (DISCOVER, OFFER, REQUEST, ACK), but also the used source/destination addresses and ports, the type of connection (unicast/broadcast), the differences between the initial and the renewing messages, and the needed firewall rules for allowing DHCP traffic to/from the own interface or to/from a DHCP relay agent.
Here it comes! :)
DHCPv4 Message Sequence Diagram
If there are any mistakes -> send me a comment.
Or download it as PDF
Security Policy on a Palo Alto
One quick example: With the usage of bidirectional policy rules on a Palo Alto, the only security policy needed for the whole DHCP setup is the following (DHCP between the DHCP server and the network – and vice versa):
Featured image “Bald Eagle Fishing Sequence” by Lorne Sykora is licensed under CC BY-NC-ND 2.0.
2 thoughts on “DHCP Sequences: Broadcast vs. Unicast”
I have a strange DHCP issue with my SRX Juniper firewall and my both PCs one of them windows 8 and the second one is windows 7 .
the second one (win7) does not have any problem with getting IP . but the first one (win8) does have a problem, it does not get IP from the SRX firewall.
I’m sure the I have configured DHCP right in the SRX .
master@SRX> show configuration system services dhcp | display set
set system services dhcp pool 10.57.50.1/24 address-range low 10.57.50.20
set system services dhcp pool 10.57.50.1/24 address-range high 10.57.50.220
set system services dhcp pool 10.57.50.1/24 maximum-lease-time 3600
set system services dhcp pool 10.57.50.1/24 default-lease-time 3600
set system services dhcp pool 10.57.50.1/24 name-server 10.57.50.2
set system services dhcp pool 10.57.50.1/24 name-server 22.214.171.124
set system services dhcp pool 10.57.50.1/24 router 10.57.50.254
set system services dhcp propagate-settings ge-0/0/0.0
I have does too many troubleshooting in my win8PC :
1- netsh reset command
2- disable / enable to the LAC
3- remove and install again to the LAC
4- assured if the IPv4 optioned is checked
5- rebooting the PC
6- tried with another RJ45 cable
on the same interface I put the win7 PC , and it WORKED ! .. but when I put the win8 it does not .
I’ve tried with another win8 PC , to see if the bug is in the first win8 pc , But guess what .. it also didn’t work ! :\
Do you have any idea what the solution might be ?
thanks in advance :)
I am sorry, but I cannot help you with this issue. So far I have not troubleshooted Win 8 DHCP problems, nor SRX DHCP problems. I am sorry.