Configure Intelligent Security using RADIUS for User Equipment to IP Address Correlation

Information such as the Subscriber ID (IMSI or SUPI) and the Equipment ID (IMEI or PEI) for User Equipment (UE) mobile devices are key identifiers for Security policy enforcement in mobile networks such as 5G and 4G/LTE networks. Mapping the IMSI or IMEI to subscriber or user IP addresses requires access to the signaling protocol traffic exchanges over the 3GPP interfaces; however, in some deployments, the 3GPP interfaces between network functions are not exposed.

Intelligent Security with RADIUS in 5G allows deployment of the firewall on the N6/SGi interface, which contains the RADIUS traffic for the management plane, and Internet Protocol traffic without outer GTP-U headers for the dataplane. The firewall inspects the RADIUS traffic to extract information for correlation with the user plane. This provides subscriber and equipment-level visibility, as well as consistent policy enforcement for vulnerabilities, malware, viruses, URLs, C2, and applications.

If you enable UEIP Correlation, the following options are not available in the same Mobile Network Protection Profile:

• GTP-C
• 5G-C
• Packet Forwarding Control Protocol (PFCP)

The following diagram represents a possible deployment for UE to IP address correlation for an N6 deployment with RADIUS.

When the UE attempts to connect with the network, the SMF exchanges authentication, authorization, and accounting messages with the DN-AAA server using RADIUS. The accounting message provides a record of the network services that the authenticated UE accesses. This message contains parameters, which include the user's ID and IPv4 or IPv6 address, that the application servers use to identify the user.

The firewall monitors the Accounting Start messages on UDP ports 1813 and 1646 and Interim Updates to map the UE to the IP address and adds the mapping to the UEIP correlation database on the firewall. The firewall also generates a log during IP address allocation.

When the firewall receives the RADIUS session end message, it removes the mapping from the correlation database on the firewall and creates a log.

Intelligent Security requires the following fields and Vendor-Specific Attributes (VSAs) in the RADIUS messages:

• Framed-IP-Address(8): <IPv4-address>
• Framed-IPv6-Prefix(97): <IPv6-prefix>
• Called-Station-Id: <APN>
• Vendor-Specific(26): VSA: t=3GPP-IMSI(1): <IMSI_value>
• Vendor-Specific(26): VSA: t=3GPP-IMEISV(20): <IMEI_value>
• Vendor-Specific(26): VSA: t=3GPP-RAT-Type(21): <RAT>

1. Enable GTP Security.
   1. Log in to the firewall web interface.
   2. Select DeviceSetupManagementGeneral Settings then select GTP Security.
   3. Click OK.
   4. Commit the change.
   5. Select DeviceSetupOperations and Reboot Device.
2. Create a Mobile Network Protection Profile.
   1. Select ObjectsSecurity ProfilesMobile Network Protection and Add a new profile.
   2. Give the profile a unique Name.
   3. Select Correlation and enable UEIP Correlation.
   4. Select the Mode you want to use.
      • Loose—(Default) When the firewall detects traffic, it queries the source or destination address to find the correlated IMEI or IMSI information. If there are no results, the firewall forwards the traffic.
      • Strict—Drops the traffic if the GTP-U query does not return any results.
   5. Uncheck the User Plane with GTP-U encapsulation option.
   6. Select RADIUS as the Source.
      Select the Source that you want the firewall to use to correlate the management plane and user plane information for subscriber-level and equipment-level Security policy enforcement. The firewall inspects traffic for the source type you select to process and extract 5G/4G identity information, such as subscriber ID (SUPI and IMSI), equipment ID (PEI and IMEI), and the IP address of the user equipment (UE), to correlate with 5G/4G subscriber Internet Protocol traffic.

   7. (Optional) Select whether you want to log UEIP correlation events when the firewall allocates an IP address to the UE (Log At Ueip Start), when the firewall releases the allocated IP address (Log At Ueip End), or both.
      The firewall logs the following GTP events during correlation that you can view by going to MonitorLogsGTP:

      • UEIP mapping start
      • UEIP mapping end

      The logs contain the following user information:

      • Subscriber Identity (including IMSI and SUPI)
      • Equipment Identity (including IMEI and PEI)
      • End User IP address allocated to UE
      • Access Point Name (APN)
      • Radio Access Technology (RAT)
3. Create a Security policy to identify and allow RADIUS traffic between the SMF and the RADIUS server.
   There are two methods for policy creation based on the necessary level of security between the SMF and the RADIUS server. Select the appropriate method based on your security needs.

   • (Recommended) To allow all traffic between the SMF and RADIUS server zone, as well as the UPF and Data Network zones:
     1. Select PoliciesSecurity and Add a unique Namefor the rule in the General tab.
     2. In the Source tab, Add the Source Zone as Any and the Source Address as Any.
     3. In the Destination tab, Add the Destination Zone as Any and the Destination Address as Any.
     4. In the Application tab, Add radius as the Application you want to allow.
     5. In the Service/URL Category tab, select the Serviceas Any.
     6. In the Actions tab, select the Action as Allow.
     7. Attach the Mobile Network Protection profile to the Security policy rule by selecting Profiles and selecting the profile as the Profile Type.
     8. Select Log at Session End if it is not already selected.
   • To allow RADIUS application traffic only between the SMF and the RADIUS server:
     1. Select PoliciesSecurity and Add a unique Namefor the rule in the General tab.
     2. In the Source tab, Add the Source Zone and Source Address of the interface that the SMF uses to communicate with the RADIUS server.
     3. In the Destination tab, Add the Destination Zone and Destination Address for the interface that contains the IP address of the RADIUS server.
     4. In the Application tab, Add radius as the Application you want to allow.
     5. In the Service/URL Category tab, select the Serviceas Any.
     6. In the Actions tab, select the Action as Allow.
     7. Attach the Mobile Network Protection profile to the Security policy rule by selecting Profiles and selecting the profile as the Profile Type.
     8. Select Log at Session End if it is not already selected.
4. Create a custom application and a Security policy that uses the custom application. (Required if you allow traffic between the SMF and RADIUS server only)
   Because the firewall applies this policy rule first, it processes the first packet of all user traffic and enables UEIP database querying, move this policy rule above any other policy rules in your Security policy for user traffic on the N6 interface. Any application-specific or IMSI/IMEI-based policy rules must occur after this policy rule.
   1. Select ObjectsApplications and Add a unique Name for the application (for example, radius-ueip).

   2. Select PoliciesSecurity and Add a unique Name for the policy rule.
   3. In the Source tab, Add the zone that contains traffic to the UPF as the Source Zone and select Any as the Source Address. If you use an IP pool for the UE IP address, add the IP pool as the Source Address .
      Don't select anything in the Source Subscriber or Source Equipment tabs.
   4. In the Destination tab, Add the zone that contains traffic to the Packet Data Network as the Destination Zone and select Any as the Destination Address.
   5. In the Application tab, Add the Applicationyou created in step 4.1.
   6. In the Service/URL Category tab, select Any as the Service.
   7. In the Actions tab, select Allow as the Action.
   8. Attach the Mobile Network Protection profile to the Security policy rule by selecting Profiles and selecting the profile you created in step 3 as the Profile Type.
   9. Select Log at Session Endif it is not already selected.
5. Create Security policy rules for user equipment (UE) traffic based on the criteria you want to use, such as IP address, application, URL category, IMSE, or IMEI.
   1. Select PoliciesSecurity and Add a unique Name for the rule.
   2. In the Source tab, Add the Source Zone and Source Address.
      If you use an IP pool for the UE IP address, add the IP pool as the Source Address .
   3. In the Source tab, Add the Source Subscriber and if required, the Source Equipment.
   4. In the Destination tab, Add the Destination Zone and Destination Address the address of the servers in the corporate network or MEC site or use any for internet access.
   5. In the Application tab, Add the Application or applications you want to allow, such as dns, web-browsing, or ssl.
   6. In the Service/URL Category tab, select the type or types of Service you want to allow.
   7. In the Actions tab, select the Action you want to take for the selected traffic (Allow the traffic or Deny it).
   8. Select Log at Session End if it is not already selected.
6. Confirm that the profile is Enabled (PoliciesSecuritySecurity Policy RuleActionsProfile SettingMobile Network Protection) and Commit the changes.
7. Verify your configuration is correct.
   1. Verify the session traffic on the firewall using the following CLI commands.
      • show session all filter application radius
      • show session all filter source <IP_address_of_UE> (where <IP_address_of_UE> is the IP address of the user equipment).
   2. Verify the mappings on the firewall display radius as the source (src).
   3. View the logs (MonitorLogsGTP) and verify that the GTP Event Type displays UEIP mapping start and UEIP mapping end.

   4. Verify the Traffic logs (MonitorLogsTraffic) display the IMSI or IMEI in the Subscriber Identity column for the UE traffic.

   5. Use the Global Counters to verify the configuration.