Cisco Cisco Expressway
Connecting Expressway to Unified CM Using TLS
These instructions explain how to take a system that is already configured and working using a TCP interconnection
between Expressway and Unified CM, and to convert that connection to use TLS instead. This process involves:
between Expressway and Unified CM, and to convert that connection to use TLS instead. This process involves:
■
Ensuring certificate trust between Unified CM and Expressway
■
Setting the Cluster Security Mode of the Unified CM to 1 (Mixed Mode)
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Configuring a SIP trunk security profile on Unified CM
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Updating the Unified CM trunk to Expressway to use TLS
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Updating the Expressway neighbor zone to Unified CM to use TLS
Ensuring Certificate Trust Between Unified CM and Expressway
For Unified CM and Expressway to establish a TLS connection with each other:
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Expressway and Unified CM must both have valid server certificates loaded (you must replace the Expressway's
default server certificate with a valid server certificate)
default server certificate with a valid server certificate)
■
Expressway must trust Unified CM’s server certificate (the root CA of the Unified CM server certificate must be
loaded onto Expressway)
loaded onto Expressway)
■
Unified CM must trust Expressway’s server certificate (the root CA of the Expressway server certificate must be
loaded onto Unified CM)
loaded onto Unified CM)
for full details about loading certificates and how to
generate CSRs on Expressway to acquire certificates from a Certificate Authority (CA).
Note:
In a clustered environment, you must install CA and server certificates on each peer/node individually.
We strongly recommend that you do not use self-signed certificates in a production environment.
Loading Server and Trust Certificates on Expressway
Expressway Server Certificate
Expressway has only one server certificate. By default, this is a certificate signed by a temporary certificate authority. We
recommend that it is replaced by a certificate generated by a trusted certificate authority.
recommend that it is replaced by a certificate generated by a trusted certificate authority.
To upload a server certificate:
1.
Go to Maintenance > Security certificates > Server certificate.
2.
Use the Browse button in the Upload new certificate section to select and upload the server certificate PEM file.
3.
If you used an external system to generate the Certificate Signing Request (CSR) you must also upload the
server private key PEM file that was used to encrypt the server certificate. (The private key file will have been
automatically generated and stored earlier if the Expressway was used to produce the CSR for this server
certificate.)
server private key PEM file that was used to encrypt the server certificate. (The private key file will have been
automatically generated and stored earlier if the Expressway was used to produce the CSR for this server
certificate.)
—
The server private key PEM file must not be password protected.
—
You cannot upload a server private key if a certificate signing request is in progress.
4.
Click Upload server certificate data.
Note:
If you are using Unified CM version 8.5(1) or earlier and are having problems establishing a TLS connection
between Expressway and Unified CM, we recommend adding the following x509 extended key attributes into the CSR:
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serverAuth (1.3.6.1.5.5.7.3.1) -- TLS Web server authentication
■
clientAuth (1.3.6.1.5.5.7.3.2) -- TLS Web client authentication
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ipsecEndSystem (1.3.6.1.5.5.7.3.5) -- IP security end system
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Cisco Expressway SIP Trunk to Unified CM Deployment Guide