DHCP Server 2003

[immorall]

Ok, I cant seem to solve this problem for the life of me. We have a 2003 server running ISA. It also is a DHCP server as well for some our clients. Everything worked fine for a while. Now, the DHCP server is not issuing out leases to any clients. There are plenty of leases to give out and it even shows in the DHCP statisitics that the DHCP server still has 100% of its leases to give out. The DHCP server also show's no Discovers, Offers, Request, Acks being sent AT ALL. I give a client a static IP on the same subnet as the scope and it is fine. It can ping the DHCP server, get out to the Internet, etc....I ran ethereal on the DHCP server's interface and it shows DHCP Discover packets on the interface, but it doesnt show Offers, Request, Acks, Nacks. I looked at the DHCP log and it shows no errors at all. It does show that it is trying to clean up its leases (normal). The DHCP server service is running. I verified this both in the services console and in the DHCP server interface. The DHCP server is authorized and the scope is activated. The ISA firewall doesnt have any deny filters at all and the subnet is defined as one of the internal networks for NAT. Its almost like the DHCP server (interface, not the GUI) sees the Discover packets, but is ignoring them. I set up another server with the same exact scope and options, on the Same subnet, and it gives out leases just fine. Anyone have a clue on what the hell this could be? Why the DHCP server would ignore the discover packets.

[cluberti]

Have you considered using the ISA server logging to see if your Offer requests are hitting the default deny rule? Honestly, it's likely the ISA firewall is likely blocking the requests once they hit the interface.

Why are you running any services on a firewall, btw? It would be easier and safer to run network services on another server, not to mention reduce the attack surface of the ISA box...