Configure Secure SIP Signaling in Contact Center Enterprise

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Updated:November 22, 2022
Document ID:218434

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    Introduction

    This document describes how to secure Session Initiation Protocol (SIP) signaling in Contact Center Enterprise (CCE) comprehensive call flow.

    Prerequisites

    Certificates generation and import are out of the scope of this document, so certificates for Cisco Unified Communication Manager (CUCM), Customer Voice Portal (CVP) call server, Cisco Virtual Voice Browser (CVVB), and Cisco Unified Border Element (CUBE) have to be created and imported to the respective components. If you use self-signed certificates, certificate exchange has to be done among different components.

    Requirements

    Cisco recommends that you have knowledge of these topics:

    • CCE
    • CVP
    • CUBE
    • CUCM
    • CVVB

    Components Used

    The information in this document is based on Package Contact Center Enterprise (PCCE), CVP, CVVB, and CUCM version 12.6, but it is also applicable to the earlier versions.

    The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.

    Configure

    The next diagram shows the components engaged in SIP signaling in the contact center comprehensive call flow. When a voice call comes to the system, first comes via the ingress gateway or CUBE, so start secure SIP configurations on CUBE. Next, configure CVP, CVVB, and CUCM.

    Inbound SIP Call Flow

    Task 1. CUBE Secure Configuration

    In this task, configure CUBE to secure the SIP protocol messages.

    Required configurations:

    • Configure a Default Trustpoint for the SIP User Agent (UA)
    • Modify the Dial-peers to use Transport Layer Security (TLS)

    Steps:

    1. Open Secure Shell (SSH) session to CUBE.
    2. Run these commands to have the SIP stack use the Certificate Authority (CA) certificate of the CUBE. CUBE establishes a SIP TLS connection from/to CUCM (198.18.133.3) and CVP (198.18.133.13).

    conf t sip-ua transport tcp tls v1.2 crypto signaling remote-addr 198.18.133.3 255.255.255.255 trustpoint ms-ca-name crypto signaling remote-addr 198.18.133.13 255.255.255.255 trustpoint ms-ca-name exit

    CUBE SSH Console

    1. Run these commands to enable TLS on the outgoing dial peer to CVP. In this example, dial-peer tag 6000 is used to route calls to CVP.

    Conf t dial-peer voice 6000 voip session target ipv4:198.18.133.13:5061 session transport tcp tls exit

    CUBE SSH Console

    Task 2. CVP Secure Configuration

    In this task, configure the CVP call server to secure the SIP protocol messages (SIP TLS).

    Steps:

    1. Log in toUCCE Web Administration.
    2. Navigate to  Call Settings > Route Settings > SIP Server Group.

    SIP Server Group Configuration on CCE Admin Portal


    Based on your configurations, you have SIP Server Groups configured for CUCM, CVVB, and CUBE. You need to set secure SIP ports to 5061 for all of them. In this example, these SIP server groups are used:

    • cucm1.dcloud.cisco.com for CUCM
    • vvb1.dcloud.cisco.com for CVVB
    • cube1.dcloud.cisco.com  for CUBE
    1. Click  cucm1.dcloud.cisco.com  and then in the  Members  tab, which shows the details of the SIP Server Group Configuration. Set SecurePort to 5061 and click  Save .

    Setting Secure SIP Port for CUCM Server Group

    1. Click vvb1.dcloud.cisco.com and then in the  Members  tab. Set SecurePort to 5061 and click  Save.

    Setting Secure SIP Port for VVB Server Group

    Task 3. CVVB Secure Configuration

    In this task, configure CVVB to secure the SIP protocol messages (SIP TLS).

    Steps:

    1. Log in to  Cisco VVB Administration  page.
    2. Navigate to  System > System Parameters.

    VVB System Parameters

    1. In the  Security Parameters  section, choose  Enable  for TLS(SIP) . Keep  Supported TLS(SIP) version  as  TLSv1.2.

    VVB Security Parameters

    1. Click  Update. Click Ok when prompted to restart CVVB engine.

    Update Security Parameters

    1. These changes require a restart of the Cisco VVB engine. In order to restart the VVB engine, navigate to Cisco VVB Serviceability then click  Go.

    Cisco VVB Serviceability

    1. Navigate to  Tools > Control Center – Network Services.

    Control Center - Network Services

    1. Choose Engine and click  Restart.

    Control Center - Network Services

    Task 4. CUCM Secure Configuration

    In order to secure SIP messages on CUCM, perform the next configurations:

    • Set CUCM Security Mode to Mixed Mode
    • Configure SIP Trunk Security Profiles for CUBE and CVP
    • Associate SIP Trunk Security Profiles to Respective SIP Trunks
    • Secure Agents’ Device Communication with CUCM

    Set CUCM Security Mode to Mixed Mode

    CUCM supports two security modes:

    • Non-secure mode (default mode)
    • Mixed mode (secure mode)

    Steps:

    1. In order to set the security mode to Mixed Mode, log in to  Cisco Unified CM Administration  interface.

    CUCM Administration Interface

    1. After you have successfully logged in to CUCM, navigate to  System > Enterprise Parameters.

    CUCM Enterprise Parameters

    1. Underneath the Security Parameters Section, check if  Cluster Security Mode is set to  0.

    CUCM Security Parameters

    1. If Cluster Security Mode is set as 0, this means cluster security mode is set to non-secure. You need to enable the mixed Mode from CLI.
    2. Open an SSH session to the CUCM.
    3. After you have successfully logged to CUCM via SSH, run this command: utils ctl set-cluster mixed-mode
    1. Type y and click Enter  when prompted. This command sets cluster security mode to mixed mode.

    CUCM SSH Console

    1. For the changes to take effect, restart  Cisco CallManager  and  Cisco CTIManager  services.
    2. In order to restart the services, navigate and log in to Cisco Unified Serviceability.

    Cisco Unified Serviceability

    1. After you have successfully logged in, navigate to  Tools > Control Center – Feature Services.

    Control Center - Feature Services

    1. Choose the server then click  Go.

    Select Server

    1. Underneath the CM services, choose Cisco CallManager  then click  Restart  button on top of the page.

    Restarting Cisco Call Manager Services

    1. Confirm the pop-up message and click  OK. Wait for the service to successfully restart.

    Info Message

    1. After a successful restart of  Cisco CallManager, choose Cisco  CTIManager  then click Restart button to restart  Cisco CTIManager  service.

    Restarting Cisco CTI Manager Service

    1. Confirm the pop-up message and click  OK. Wait for the service to successfully restart.

    Info Message

    1. After services successfully restart, verify cluster security mode is set to mixed mode, navigate to CUCM administration as explained in Step 5. then check the  Cluster Security Mode. Now it must be set to  1.

    Cluster Security Mode is to the Value of '1'

    Configure SIP Trunk Security Profiles for CUBE and CVP

    Steps:

    1. Log in to  CUCM administration  interface.
    2. After successful login to CUCM, navigate to System > Security > SIP Trunk Security Profile  in order to create a device security profile for CUBE.

    CUCM SIP Trunk Security Profile

    1. On the top left, click  Add New  in order to add a new profile.

    Add New CUCM SIP Trunk Security Profile

    1. Configure SIP Trunk Security Profile as shown in this image then click  Save  at the bottom left of the page to  Save  it.

    Add CUCM SIP Trunk Security Profile for CUBE

    5. Ensure to set the  Secure Certificate Subject or Subject Alternate Name  to the Common Name (CN) of the CUBE certificate as it must match.

    6. Click  Copy  button and change the Name to  SecureSipTLSforCVP and the Secure Certificate Subject to the CN of the CVP call server certificate as it must match. Click Save button.

    Add CUCM SIP Trunk Security Profile for CVP

    Associate SIP Trunk Security Profiles to Respective SIP Trunks

    Steps:

    1. On the CUCM Administration page, navigate to  Device > Trunk.

    CUCM Trunk Configuration for CUBE

    1. Search for CUBE trunk. In this example, the CUBE trunk name is  vCube . Click  Find.

    Find SIP Trunks on CUCM for CUBE

    1. Click vCUBE to open the vCUBE trunk configuration page.
    2. Scroll down to SIP Information section, and change the  Destination Port  to  5061.
    3. Change SIP Trunk Security Profile to  SecureSIPTLSForCube.

    SIP Trunk Configuration for CUBE

    1. Click Save then Rest in order to  Save and apply changes.

    Save Configuration


    Info Message

    1. Navigate to  Device > Trunk, and search for CVP trunk. In this example, the CVP trunk name is  cvp-SIP-Trunk . Click  Find.

    CUCM Trunk Configuration for CVP

    1. Click CVP-SIP-Trunk in order to open the CVP trunk configuration page.
    2. Scroll down to SIP Information section, and change  Destination Port  to  5061 .
    3. Change  SIP Trunk Security Profile  to  SecureSIPTLSForCvp.

    Find SIP Trunks on CUCM for CVP

    1. Click  Save then Rest in order to save and apply changes.

    SIP Trunk Configuration for CVP

    Save Configuration

    Secure Agents’ Device Communication with CUCM

    In order to enable security features for a device, you must install a Locally Significant Certificate (LSC) and assign a security profile to that device. The LSC possesses the public key for the endpoint, which is signed by the Certificate Authority Proxy Function (CAPF) private key. It is not installed on phones by default.

    Steps:

    1. Log in to Cisco Unified Serviceability Interface.
    2. Navigate to  Tools > Service Activation.

    Info Message

    1. Choose the CUCM server and Click  Go .

    CUCM Service Activation

    1. Check Cisco Certificate Authority Proxy Function and click  Save to activate the service. Click Ok to confirm.

    Select Server

    1. Ensure the service is activated then navigate to  Cisco Unified CM Administration.

    Activate Cisco Certificate Authority Proxy Function Service

    1. After you have successfully logged in to CUCM administration, navigate to  System > Security > Phone Security Profile  in order to create a device security profile for the agent device.

    CUCM Administration

    1. Find the security profiles respective to your agent device type. In this example, a soft phone is used, so choose  Cisco Unified Client Services Framework - Standard SIP Non-Secure Profile . Click CopyPhone Security Profile in order to copy this profile.

    Copy Existing Phone Security Profile

    1. Rename the profile to  Cisco Unified Client Services Framework - Secure Profile,change the parameters as shown in this image, then click  Save at the top left of the page.

    Add New Phone Security Profile

    1. After the successful creation of the phone device profile, navigate to  Device > Phone.

    Phone Configuration

    1. Click Find in order to list all available phones, then click agent phone.
    2. Agent phone configuration page opens. Find Certification Authority Proxy Function (CAPF) Information section. In order to install LSC, set Certificate Operation to Install/Upgrade and Operation Completes by to any future date.

    Setting CAPF Parameters

    1. Find Protocol Specific Information section. Change Device Security Profile to  Cisco Unified Client Services Framework – Secure Profile.

    Assigning Device Security Profile to IP Phone

    1. Click  Save at the top left of the page. Ensure the changes are saved successfully and click  Reset.

    Save Configuration

    1. A pop-up window opens, click  Reset  to confirm the action.

    Phone Reset

    1. After the agent device registers once again with CUCM, refresh the current page and verify the LSC is installed successfully. Check Certification Authority Proxy Function (CAPF) Information section, Certificate Operation must be set to  No Pending Operation, and Certificate Operation Status is set to  Upgrade Success .

    CAPF Information is Updated

    1. Refer Steps. 7-13 in order to secure other agents devices that you want to use to secure SIP with CUCM.

    Verify

    In order to validate SIP signaling is properly secured, perform these steps:

    1. Open SSH session to vCUBE, run the command show sip-ua connections tcp tls detail , and confirm that there is no TLS connection established at the moment with CVP (198.18.133.13).

    show sip-ua connections tcp tls detail Output on CUBE SSH Console

    Note: At this moment, only one active TLS session with CUCM, for SIP Options is enabled on CUCM (198.18.133.3). If no SIP Options are enabled, no SIP TLS connection exists.

    1. Log in to CVP and start Wireshark.
    2. Make a test call to contact center number.
    3. Navigate to the CVP session; on Wireshark, run this filter in order to check SIP signaling with CUBE:
      ip.addr == 198.18.133.226 && tls && tcp.port==5061

    Packet Capture Filtering CVP Secure SIP Signals Between CVP and CUBE

    Check: Is SIP over TLS connection established? If yes, the output confirms SIP signals between CVP and CUBE are secured.

    5. Check the SIP TLS connection between CVP and CVVB. In the same Wireshark session, run this filter:

    ip.addr == 198.18.133.143 && tls && tcp.port==5061

    Packet Capture Filtering CVP Secure SIP Signals Between CVP and VVB

    Check: Is SIP over TLS connection established? If yes, the output confirms SIP signals between CVP and CVVB are secured.

    6. You can also verify the SIP TLS connection with CVP from CUBE. Navigate to the vCUBE SSH session, and run this command to check secure sip signals:
    show sip-ua connections tcp tls detail


    SIP TLS Connection Between CVP and CUBE from CUBE SSH Console

    Check: Is SIP over TLS connection established with CVP? If yes, the output confirms SIP signals between CVP and CUBE are secured.

    7. At this moment, the call is active and you hear Music on Hold (MOH) as there is no agent available to answer the call.

    8. Make the agent available to answer the call.

    .Make Agent Ready on Finesse Agent Desktop

    9. Agent gets reserved and the call is routed to him/her. Click Answer to answer the call.

    Answer Incoming Call on Finesse Desktop


    10. Call connects to the agent.

    11. In order to verify SIP signals between CVP and CUCM, navigate to the CVP session, and run this filter in Wireshark:
    ip.addr == 198.18.133.3 && tls && tcp.port==5061

    Packet Capture Filtering Secure SIP Signals between CVP and CUCM

    Check: Are all SIP communications with CUCM (198.18.133.3) over TLS? If yes, the output confirms SIP signals between CVP and CUCM are secured.

    Troubleshoot

    If TLS is not established, run these commands on CUBE to enable debug TLS to troubleshoot:

    • Debug ssl openssl errors
    • Debug ssl openssl msg
    • Debug ssl openssl states

    Revision History

    Revision Publish Date Comments
    1.0
    23-Nov-2022
    Initial Release
    TAC Authored

    Contributed by Cisco Engineers

    • Mohamed Mohasseb
      Technical Consulting Engineer

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