I am about to configure a back-to-back ISA configuration. As Tom Shinder writes i could chain the firewall services. But I could not...Internal ISA seems to be unaware of the external ISA with an eventlog that describes the unavailability of the other ISA. I do not have deep konwledge about firewall chaning and I think the problem is about the different roles of the ISA servers. Shortly, internal ISA is in integrated mode and external ISA is in firewall-mode. Do you know if firewall chaining can work with these ISA servers? Thanks for any comment, Goktug PS: Also I want to know why it is more secure using firewall chaining instead of defining rules to a fix ip addres?