Cisco Cisco Email Security Appliance C160 Mode D'Emploi
5-2
User Guide for AsyncOS 9.8 for Cisco Email Security Appliances
Chapter 5 Configuring the Gateway to Receive Email
Working with Listeners
•
Which hosts that are allowed to connect to the listener. Define a set of rules that control incoming
connections from remote hosts. For example, you can define remote hosts and whether or not they
can connect to the listener. For details on how to do this, see
connections from remote hosts. For example, you can define remote hosts and whether or not they
can connect to the listener. For details on how to do this, see
•
(Public listeners only) The local domains for which the listener accepts messages. Define which
recipients are accepted by the public listener. For example, if your organization uses the domain
recipients are accepted by the public listener. For example, if your organization uses the domain
currentcompany.com
and it previously used
oldcompany.com
, then you might accept messages for
both
currentcompany.com
and
oldcompany.com
. For details on how to do this, see
The settings configured in the listener, including its Host Access Table and Recipient Access Table,
affect how the listener communicates with an SMTP server during the SMTP conversation. This allows
the appliance to block a spamming host before the connection is closed.
affect how the listener communicates with an SMTP server during the SMTP conversation. This allows
the appliance to block a spamming host before the connection is closed.
Figure 5-1
Relationship Between Listeners, IP Interfaces, and Physical Ethernet Interfaces
Working with Listeners
Configure listeners on the Network > Listeners page in the GUI, or using the
listenerconfig
command
in the CLI.
You can define global settings that apply to all listeners. For more information, see
.
Consider the following rules and guidelines when working with and configuring listeners on the
appliance:
appliance:
•
You can define multiple listeners per configured IP interface, but each listener must use a different
port.
port.
•
By default, listeners use SMTP as the mail protocol to service email connections. However, you can
also configure the appliance to service email connections using Quick Mail Queuing Protocol
(QMQP). Do this using the
also configure the appliance to service email connections using Quick Mail Queuing Protocol
(QMQP). Do this using the
listenerconfig
CLI command.
•
Listeners support both Internet Protocol version 4 (IPv4) and version 6 (IPv6) addresses. You can
use either protocol version or both on a single listener. The listener uses the same protocol version
for mail delivery as the connecting host. For example, if the listener is configured for both IPv4 and
IPv6 and connects to a host that uses IPv6, the listener uses IPv6. However, if the listener is
configured to only use IPv6 addresses, it cannot connect to a host that is only using IPv4 addresses.
use either protocol version or both on a single listener. The listener uses the same protocol version
for mail delivery as the connecting host. For example, if the listener is configured for both IPv4 and
IPv6 and connects to a host that uses IPv6, the listener uses IPv6. However, if the listener is
configured to only use IPv6 addresses, it cannot connect to a host that is only using IPv4 addresses.
•
At least one listener (with default values) is configured on the appliance after running the System
Setup Wizard. However, when you create a listener manually, AsyncOS does not use these default
SBRS values.
Setup Wizard. However, when you create a listener manually, AsyncOS does not use these default
SBRS values.