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30-2
Cisco ASA Series Firewall ASDM Configuration Guide
Chapter 30 Configuring the ASA CX Module
Information About the ASA CX Module
How the ASA CX Module Works with the ASA
The ASA CX module runs a separate application from the ASA. The ASA CX module includes external
management interface(s) so you can connect to the ASA CX module directly. Any data interfaces on the
ASA CX module are used for ASA traffic only.
Traffic goes through the firewall checks before being forwarded to the ASA CX module. When you
identify traffic for ASA CX inspection on the ASA, traffic flows through the ASA and the ASA CX
module as follows:
1. Traffic enters the ASA.
2. Incoming VPN traffic is decrypted.
3. Firewall policies are applied.
4. Traffic is sent to the ASA CX module.
5. The ASA CX module applies its security policy to the traffic, and takes appropriate actions.
6. Valid traffic is sent back to the ASA; the ASA CX module might block some traffic according to its
security policy, and that traffic is not passed on.
7. Outgoing VPN traffic is encrypted.
8. Traffic exits the ASA.
Figure 30-1 shows the traffic flow when using the ASA CX module. In this example, the ASA CX
module automatically blocks traffic that is not allowed for a certain application. All other traffic is
forwarded through the ASA.
Figure 30-1 ASA CX Module Traffic Flow in the ASA
Note If you have a connection between hosts on two ASA interfaces, and the ASA CX service policy is only
configured for one of the interfaces, then all traffic between these hosts is sent to the ASA CX module,
including traffic originating on the non-ASA CX interface (because the feature is bidirectional).
However, the ASA only performs the authentication proxy on the interface to which the service policy
is applied, because authentication proxy is applied only to ingress traffic (see the “Information About
Authentication Proxy” section on page 30-5).
ASA
Main System
ASA CX
Diverted Traffic
ASA CX inspection
VPN
Decryption
Firewall
Policy
Block
inside
outside
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