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Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter 53 Configuring the TLS Proxy for Encrypted Voice Inspection
CTL Provider
When you are configuring the TLS Proxy for the Phone Proxy, select the certificate that has a
filename beginning with _internal_PP_. When you create the CTL file for the Phone Proxy, the
ASA, creates an internal trustpoint used by the Phone Proxy to sign the TFTP files. The trustpoint
is named _internal_PP_ctl-instance_filename.
The server proxy certificate is used to specify the trustpoint to present during the TLS handshake. The
trustpoint can be self-signed or enrolled locally with the certificate service on the proxy. For example,
for the Phone Proxy, the server proxy certificate is used by the Phone Proxy during the handshake with
the IP phones.
Step 3 To install the TLS server certificate in the ASA trust store, so that the ASA can authenticate the TLS
server during TLS handshake between the proxy and the TLS server, click Install TLS Server’s
Certificate.
The Manage CA Certificates dialog box opens. See the “Guidelines and Limitations” section on
page 44-9. Click Add to open the Install Certificate dialog box. See the “Adding or Installing a CA
Certificate” section on page 44-10.
When you are configuring the TLS Proxy for the Phone Proxy, click Install TLS Server’s Certificate
and install the Cisco Unified Call Manager (CUCM) certificate so that the proxy can authenticate the IP
phones on behalf of the CUCM server.
Step 4 To require the ASA to present a certificate and authenticate the TLS client during TLS handshake, check
the Enable client authentication during TLS Proxy handshake check box.
When adding a TLS Proxy Instance for Mobile Advantage (the CUMC client and CUMA server), disable
the check box when the client is incapable of sending a client certificate.
Step 5 Click Next.
The Add TLS Proxy Instance Wizard – Client Configuration dialog box opens. In this step of the wizard,
configure the client proxy parameters for original TLS Client—the CUMC client for Mobile Advantage,
CUP or MS LCS/OCS client for Presence Federation, or the IP phone for the Phone Proxy. See Add TLS
Proxy Instance Wizard – Client Configuration, page 53-10.
After configuring the client proxy parameters, the wizard provides instructions on the steps to complete
outside the ASDM to make the TLS Proxy fully functional (see Add TLS Proxy Instance Wizard – Other
Steps, page 53-12).
Add TLS Proxy Instance Wizard – Client Configuration
Note This feature is not supported for the Adaptive Security Appliance version 8.1.2.
Use the Add TLS Proxy Instance Wizard to add a TLS Proxy to enable inspection of SSL encrypted VoIP
signaling, namely Skinny and SIP, interacting with Cisco Call Manager and to support the Cisco Unified
Communications features on the ASA.
This wizard is available from the Configuration > Firewall > Unified Communications > TLS Proxy
pane.
Step 1 Complete the first two steps of the Add TLS Proxy Instance Wizard. See Adding a TLS Proxy Instance,
page 53-8 and Add TLS Proxy Instance Wizard – Client Configuration, page 53-10.
The Add TLS Proxy Instance Wizard – Client Configuration dialog box opens.