Cisco Cisco Email Security Appliance X1070 ユーザーガイド
8-293
Cisco IronPort AsyncOS 7.1 for Email Configuration Guide
OL-22158-02
Chapter 8 Anti-Spam
as a hop. See
information). AsyncOS looks for the first IP address following the first
occurrence of the parsing character or string in the Received: header
corresponding to the number of specified hops. For example, if you specify two
hops, the second Received: header, working backward from the IronPort
appliance is parsed. If the parsing character is not found, or if there is not a valid
IP address found, the IronPort appliance uses the real IP address of the connecting
machine.
occurrence of the parsing character or string in the Received: header
corresponding to the number of specified hops. For example, if you specify two
hops, the second Received: header, working backward from the IronPort
appliance is parsed. If the parsing character is not found, or if there is not a valid
IP address found, the IronPort appliance uses the real IP address of the connecting
machine.
If you specify an opening square bracket (
[
) and two hops for the following
example mail headers, the IP address of the external machine is 7.8.9.1. However,
if you specify an closing parenthesis (
if you specify an closing parenthesis (
)
) as the parsing character, a valid IP
address will not be found. In this case, the Incoming Relays feature is treated as
disabled, and the IP of the connecting machine is used (10.2.3.5).
disabled, and the IP of the connecting machine is used (10.2.3.5).
In the example in
the incoming relays are:
•
Path A — 10.2.3.5 (with 2 hops when using received headers) and
•
Path B — 10.2.6.1 (with 2 hops when using received headers)
shows example email headers for a message as it moves through several
hops on its way to the IronPort appliance as in
. This example shows
extraneous headers (ignored by your IronPort appliance) which are present once
the message has arrived in the recipient’s inbox. The number of hops to specify
would be two.
the message has arrived in the recipient’s inbox. The number of hops to specify
would be two.
shows the headers for the same email message, without
the extraneous headers
Table 8-2
A Series of Received: Headers (Path A Example 1)
1
Microsoft Mail Internet Headers Version 2.0
Received: from smemail.rand.org ([10.2.2.7]) by
smmail5.customerdoamin.org with Microsoft
SMTPSVC(5.0.2195.6713);
Received: from ironport.customerdomain.org ([10.2.3.6]) by
smemail.customerdoamin.org with Microsoft
SMTPSVC(5.0.2195.6713);
2
Received: from mta.customerdomain.org ([10.2.3.5]) by
ironport.customerdomain.org with ESMTP; 21 Sep 2005 13:46:07
-0700
3
Received: from mx.customerdomain.org (mx.customerdomain.org)
[10.2.3.4]) by mta.customerdomain.org (8.12.11/8.12.11) with
ESMTP id j8LKkWu1008155 for <joefoo@customerdomain.org>