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Re: [FW-1] RBL List?
"Sabino, Justin" wrote:
>
> Clark,
>
> Can you explain what you mean by "losing mail headers"? Do you simply mean
> that I will see e-mails in my clients (such as Outlook or Eudora) with blank
> headers in the from/to address? If that's the case I've yet to see that and
> have been using the SMTP security server for inbound mail for about a year
> now. If not, please explain.
>
> J. Sabino
Sabino,
The "Receieved:" line from the previous hop in the SMTP path is dropped
by the FW-1 SMTP server. So, if you have,
Foreign MUA
|
v
Foreign MTA ----> FW-1 MTA ----> Internal MTA
You'll have headers like,
Received: from FW-1-internal-ip (FW-1-internal-ip [aaa.bbb.ccc.ddd]) by
internal-MTA blah, blah, blah
Received: from Foreign-MUA (Foreign-MUA [eee.fff.ggg.hhh]) by
Forgein-MTA blah, blah, blah
The "Received:" line for the transfer from Foreign MTA to FW-1 MTA is
lost. That means you don't have the Foreign MTA's IP address recorded
by any machine you trust in the mail headers.
The reason it does that is so you can hide your internal mail server
if you use the FW-1 SMTP server for _outgoing_ email. However, it hides
the external mail server on _incoming_ mail which is actually a security
liability. To see where an email actually came from, you need to go look
in the firewall logs. A clued Joe User who wants to check that an email
really came from where it claims by looking at the "Received:" lines
cannot do it.
If someone knows how to turn this misfeature off, I would _love_ to hear
about it.
--
Crist J. Clark [email protected]
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