IronPort - advanced configuration guide

Listeners Overview
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Cisco IronPort AsyncOS 7.6 for Email Advanced Configuration Guide
Chapter 1 Customizing Listeners
The Network > Listeners page and the listenerconfig command in the CLI allow you to create, edit,
and delete a listener. Cisco IronPort AsyncOS requires that you specify criteria that messages must meet
in order to be accepted and then relayed to recipient hosts — either internal to your network or to external
recipients on the Internet.
These qualifying criteria are defined in listeners; collectively, they ultimately define and enforce your
mail flow policies. Listeners also define how the Cisco IronPort appliance communicates with the
system that is injecting email.
Each listener is composed of the criteria shown in Table 1-1.
Table 1-1 Criteria for Listeners
Name Unique nickname you supply for the listener, for future reference. The names you
define for listeners are case-sensitive. AsyncOS will not allow you to create two
identical listener names.
IP interface Listeners are assigned to IP interfaces. The IP interface is defined by the
interfaceconfig command. Any IP interfaces must be configured using the
System Setup Wizard or the systemsetup command or the IP Interfaces page (or
the interfaceconfig command) before you create and assign a listener to it. The
version of the Internet Protocol address of the interface determines the type of
traffic the listener accepts. If the IP interface has both an IPv4 and IPv6 address,
then the listener can accept connections from both IPv4 and IPv6 addresses.
Mail protocol The mail protocol to used for email receiving: either SMTP or QMQP (only
available via the listenerconfig command in the CLI).
IP port The specific IP port used for connections to the listener. By default, SMTP uses
port 25 and QMQP uses port 628.
Listener Type: Public Public and private listeners are used for most configurations. By
Private convention, private listeners are intended to be used for private
(internal) networks, while public listeners contain default
characteristics for receiving email from the Internet.
Blackhole “Blackhole” listeners can be used for testing or troubleshooting
purposes. When you create a blackhole listener, you choose whether
messages are written to disk or not before they are deleted. (See
“Testing and Troubleshooting” in the Cisco IronPort AsyncOS for
Email Daily Management Guide for more information.) Writing
messages to disk before deleting them can help you measure the rate
of receiving and the speed of the queue. A listener that doesn’t write
messages to disk can help you measure the pure rate of receiving
from your message generation systems. This listener type is only
available through the listenerconfig command in the CLI.
In addition to these criteria, you can also configure the following for each listener:
SMTP Address Parsing Options (optional settings for controlling parsing in SMTP “MAIL FROM”
and “RCPT TO,” see SMTP Address Parsing Options, page 1-8)
Advanced Configuration Options (optional settings for customizing the behavior of the Listener, see
Advanced Configuration Options, page 1-11)
LDAP Options (optional settings for controlling LDAP queries associated with this Listener, see
LDAP Options, page 1-12)
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