Configure GTP Stateful Inspection
Enable GTP security, configure a GTP Protection profile, and attach the profile to a Security policy rule to secure GTP traffic.
GTP comprises three types of traffic—control plane (GTP-C), user plane (GTP-U), and charging (GTP’ derived from GTP-C) traffic. Enabling GTP security on the Palo Alto Networks firewall allows you to statefully inspect, validate, filter, and perform security checks on GTPv2-C, GTPv1-C and GTP-U protocol messages.
Use the following workflow to enable stateful inspection and protocol validation for GTPv1-C, GTPv2-C, and GTP-U traffic. In addition, you can configure the firewall to inspect GTP-U content, filter GTP outer sessions based on APN, IMSI-Prefix and RAT, and enable overbilling protection for mobile subscribers. After you enable GTP, the options for configuring GTP security and monitoring GTP traffic become available on the firewall. Firewalls securing GTP traffic can be deployed in an active/passive HA; active/active HA is not supported.
- Enable GTP Security.
- Log in to the firewall web interface.
- Select. SelectDeviceSetupManagementGeneral SettingsGTP Security.
- Committhe change.
- SelectandDeviceSetupOperationsReboot Device.Enabling or disabling GTP Security requires a commit and a reboot; the best practice is to commit and reboot at this point. After you enable GTP Security, the options for configuring and monitoring GTP traffic become available on the firewall. If you disable GTP Security, you must also Commit your change and reboot the firewall. After you disable GTP Security, the firewall does not perform GTP stateful inspection, but still checks GTP packets against Security policy rules and still applies App-ID.
- (Optional) Beginning with PAN-OS 9.0.5, you can gracefully enable GTP stateful inspection to minimize disruption when you deploy a new firewall or migrate GTP traffic.
- >set gtp nodrop yesThe firewall continues to perform GTP stateful inspection and generate logs, but won’t drop GTPv2, GTPv1-C, or GTP-U packets that fail GTP stateful inspection. When you later decide to re-enable the firewall to drop packets that fail GTP stateful inspection, use the CLI operational command:set gtp nodrop no(this is the default setting).
- >show gtp infoThe firewall displays whether GTP stateful inspection is gracefully enabled (gtp no drop: True) or not (gtp no drop: False).
- Create a GTP Protection profile to inspect GTP traffic.
- SelectandObjectsSecurity ProfilesGTP ProtectionAdda new profile.
- Give the profile a descriptiveName.
- If the firewall is in Multiple Virtual System Mode, enable the profile to beSharedby all virtual systems.
- Set up GTP Protection Profile for the GTP version(s) you want to inspect and configure the available options for filtering, overbilling protection, and logging GTP messages for your compliance and troubleshooting needs.
- Create a Security policy rule to allow GTP traffic on your network.
- SelectandPoliciesSecurityAdda descriptiveNamefor the rule in theGeneraltab.
- In theSourcetab,AddtheSource Zone.
- In theDestinationtab,AddtheDestination Zone.Restrict access to specific components in the EPC network; consider using address objects in theDestination Addressfield to enable access to specific IP addresses.
- In theApplicationtab,Addthe applications that correspond to the network services you want to safely allow. For example, selectgtp-v1,gtp-v2, andgtp-u. Make sure to select the applications you enabled for inspection in the GTP Protection profile.
- In theService/URL Categorytab, change theServicefromapplication-defaulttoany.
- In theActionstab, set theActiontoAllow.
- Attach the GTP Protection profile to the Security policy rule. ForProfile Type, selectProfilesand select the GTP Protection profile you set up earlier.
- Verify thatLog at Session Endis enabled. GTP session start and GTP session end events are logged only when you enableLog at Session StartandLog at Session Endin a Security policy rule. The session start and session end logs are available under. All other GTP events are logged based on the settings you enabled in the GTP Protection profile and are also available underMonitorLogsGTP.MonitorLogsGTPBy default, the log storage quota for GTP is 2% of the total log storage capacity for the firewall model. Because GTP logs are high volume, increase the log quota () or set up log forwarding to an external server.DeviceSetupManagement
- (Optional) Block GTPv0 traffic coming into your network. Add a Security policy rule to deny applicationgtpv0. 3GPP recommends that a GTPv2 or GTPv1 entity that listens to the GTPv0 port should silently discard any GTPv0 messages it receives. The 3GPP Rel-8 GTPv1 specification removed support for GTPv1 to GTPv0 interworking; hence, a Palo Alto Networks firewall does not support stateful inspection of GTPv0 traffic.
- Commityour policies to the running configuration on the firewall.
- Monitor GTP Traffic to verify that you set up GTP inspection effectively for your visibility and logging needs, and to view the GTP traffic in your network.
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