OK. Nothing like looking at a real ruleset to sort things out. The input chain appears to be working properly to allow port-25 traffic in, since this rule shows matching packets:

   20   800 ACCEPT     tcp  ------ 0xFF 0x00  eth0
0.0.0.0/0            0.0.0.0/0             * ->   25
Since you are port forwarding, the forward chain does not enter into it. Since fairq has no port-25 rules, the packets should drop back to output and be included in what its final rule ACCEPTs.

Assuming this is the right IP address for the Exchange server, the port-forwarding part looks OK

TCP  216.70.236.236       192.168.1.4                25       25     8    10
So ... it's not a firewall problem in the narrow sense; that is, it is not the firewalling part of the Dachstein setup that's causing the problem, though there may still be a problem with the Dachstein router/firewall in a less specific sense. But since forwarding to the Web server works, we can assume no Dachstein problems at the link layer or with the routing table.

But with all of that, I cannot connect (using telnet) to your mail server from here (though I can ping you and connect to the Web server).

So ... how thoroughly have you checked the Exchange server for configuration problems? Is the Dachstein router its default gateway (and not the proxy server at 216.70.236.235)? Does Exchange do any authentication (such as auth) of a sort that might work with the proxy server but not an ordnary port-forwarding router? I hesitate to go down this road very far, since I suspect you know more about Windows sysadmin issues than I do, but I would encourage you to spend some time thinking about possible problems with Exchange or the server it runs on.

Is the Dachstein router replacing a prior router of some sort? Or is this a new connection (that is, did everything previously use the proxy server at 216.70.236.235)?


At 02:32 PM 2/10/03 -0800, Doug Sampson wrote:
[detailed diagnostics and discussion deleted]
For almost 2 years, we've used TelePacific, a telecommunications provider
with full ISP functions. We currently use a fractional T-1 link. We've never
had a problem with them when it comes to providing full ISP functionality.

I'm thinking there *has* to be a misconfiguration of the firewall. The
question is where do I go from here? All I have on the firewall is dnscache,
tinydns, weblet, and sshd besides the usual Dachstein files.



--
-------------------------------------------"Never tell me the odds!"--------
Ray Olszewski					-- Han Solo
Palo Alto, California, USA			  [EMAIL PROTECTED]
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