Firewall Wizards mailing list archives

Re: FW-1 and RPC with MSDTC


From: Darren Reed <darrenr () reed wattle id au>
Date: Fri, 12 Jan 2001 05:58:15 +1100 (EST)

I think you've misunderstood the question.  At least when one uses Sun RPC
there is a "program number" (/etc/rpc) for each RPC service.  FW-1 allows
you to control access across the firewall based on the RPC number (it's
encoded into the RPC packets).

On the Microsoft front, I've no idea if they have a similar mechanism but
I suspect they do.  Afterall, how else do you get the right port number
back to a query?  The documentation in Samba provides some details and with
some protocol analysis I was able to write a RPC proxy for IP Filter so I
could firewall an Exchange server and still have things work without having
to open up a bunch of ports for no good reason - only 137/tcp or whatever
it is where those lookups happen.

Darren

In some email I received from Michael Nelson, sie wrote:
That's because the RPC port number is random. See
http://www.microsoft.com/com/wpaper/dcomfw.asp (written by yours truly)
for more info. The info
applies to RPC as well as DCOM.

-mike

On Tue, 9 Jan 2001, Javier Megias wrote:

We're trying to get one server, that has IIS4 with MSDTC components talk
with a SQL Server 7 database with MSDTC,that is in the other interface of
the firewall (checkPoint FW-1 SP3). It complains that it can't use RPC or
that the RPC call isn't working., so we're triying to find out what RPC app
numer we must use; have tried almost everything, and we can't get it to
work. The IIS is inside a NT Domain, and the SQL Server 7 is inside a NT
group.

                    IIS ----------- FW-1 ------SQLServer7

I think that the fact could be that we don't really know how RPC really
works :-) . Any wizard could light it?
Thanks,
Javier Megias

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