ISP blocking RPC over HTTP?

From: "Andrew English" <andrew@xxxxxxxxxxxxxxxxxxxxxx>
To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
Date: Wed, 23 Feb 2005 10:32:14 -0500

[Internet IP 69.157.202.123]
    |
    |
    |
[SS6300 Router IP 10.10.10.1] 
    |
    |-- [Notebook IP 10.10.10.5 / GW 10.10.10.1 / DNS - 4.2.2.1]
    |-- [ISA Server IP 10.10.10.2 -- all DMZ traffic from Router]
    |
[ISA Server IP 192.168.1.8 (internal) - IP 10.10.10.2 (external)]
    |
[exchange.smoothrunnings.ca IP 192.168.1.4]
    |
[Rest of the LAN]


Problem:

RPC over HTTP does not seem to work from the outside world.

Testing:

Notebook used: HP Omnibook 6000 P3-1Ghz/512/40/CD etc. 
Operating System: Windows XP SP2 with latest updates
Software: Microsoft Office 2003 Professional SP1 with all updates
TCP/IP Setup: look above

If I set the host file on the notebook to point to my internet IP
address (69.157.202.123) for exchange.smoothrunnings.ca since the
owa.smoothrunnings.ca is registered I am not able to login to the RPC
over HTTP server.

If I set the hosts file on the notebook to point to my external IP on
ISA Server (10.10.10.2) I am able to login via RPC over HTTP without any
problems, which suggests to me that RPC over HTTP is working properly. 

Second phase:

I setup a new user on AD and went to a totally external source for
internet access, I setup the host file to point to the internet IP
address and attempt to connect to the same account I was able to when
using the ISA external IP. I waited, and waited some more then got the
message that Outlook could not login.

I then reconfigured the host file to the external IP of ISA Server and
got the same error message.

I also tried to connect to this company who has their DSL connected
directly to their ISA box using the same methods on the host file as I
did for my own setup, I got the same error message both times.

We have put a cheap cable/dsl router between this companies internet
connection and their ISA box and were able to successfully connect
through ISA external LAN IP address, but not through the internet
itself.

Question:

What are all the ports that RPC over HTTP uses? Its fair to ask the ISP
if they are blocking them, as I already said in another message most
ISP's block port 135 which is the standard port RPC uses. 

Thanks
Andrew

ISP blocking RPC over HTTP?

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