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Cisco ASA Series Firewall ASDM Configuration Guide
Chapter 18 Configuring the TLS Proxy for Encrypted Voice Inspection
CTL Provider
For information on the Cisco CTL Client, see “Configuring the Cisco CTL Client” in Cisco
Unified CallManager Security Guide.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/security/5_0_4/secuauth.html
To install the CTL file on the ASA, go to Configuration > Firewall > Unified Communications
> CTL Provider > Add. The Add CTL Provider dialog box opens. For information on using this
dialog box to install the CTL file, see Add/Edit CTL Provider, page 18-7.
–
Create a CTL provider instance for connections from the CTL clients. See Add/Edit CTL
Provider, page 18-7.
Edit TLS Proxy Instance – Server Configuration
Note This feature is not supported for the Adaptive Security Appliance version 8.1.2.
The TLS Proxy enables 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.
Use the Edit TLS Proxy – Server Configuration tab to edit the server proxy parameters for the original
TLS Server—the Cisco Unified Call Manager (CUCM) server, the Cisco Unified Presence Server
(CUPS), or the Cisco Unified Mobility Advantage (CUMA) server.
Step 1 Open the Configuration > Firewall > Unified Communications > TLS Proxy pane.
Step 2 To edit a TLS Proxy Instance, click Edit.
The Edit TLS Proxy Instance dialog box opens.
Step 3 If necessary, click the Server Configuration tab.
Step 4 Specify the server proxy certificate by doing one of the following:
• To add a new certificate, click Manage. The Manage Identify Certificates dialog box opens.
When the Phone Proxy is operating in a mixed-mode CUCM cluster, you must import the CUCM
certificate by clicking Add in the Manage Identify Certificates dialog box. See the “Configuring CA
Certificate Authentication” section on page 40-12 in the general operations configuration guide.
• To select an existing certificate, select one from the drop-down list.
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 5 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.