Problem Description =================== I am working a customer issue which they are setting up RPC server (Not exchange server) behind ISA. There is a DCOM sample application as client and server. Client is on the external side of the ISA and the RPC server is behind ISA. Also I have setup a lab in my office and I am having the same problem. The ISA is installed in integrated mode. Site and content rules allows all destinations and protocol rules allow all IP traffics applies to any request. The RPC filter under extension application filter is enabled. I have setup a server publishing rule by using "Any RPC Server". I have created protocol definition for TCP port 135 inbound and outbound. Just for testing I have created ip packet filters for any protocol both direction (UDP and TCP), again just for testing to make sure everything is open. On the RPC server I have installed firewall client. Also I tested as SecNAT. The result is the same. The problem is when the client tries to access the RPC server is receiving an error mssg "the RPC server is unavailable". It works if there is no ISA in between. Actions Taken #1 ============= I do see an RCP request going out in frame 115 but no response is coming back. Have you taken a trace on the internal side on the ISA to see if it receives a response from the RPC server? Also please look at these articles and see if they apply here: Multiple RPC servers publishing the same RPC interface is not su[idea] ID: Q278606 RPC Clients Cannot Connect to the Servers Behind ISA Server [ntrelease] ID: Q312893 I would take a simultaneuous trace on the internal and external interfaces to see what happens to the RPC Request.. Actions Taken #2 ============= Yes I have run the trace on the internal and external nic and there is not packects on the internal interface. Also I have checked those two and + articles. I am at the customer site and still seeing the same problem. Also I have setup protocol definitions for port 1024 and higher.