Enabling Stateful Inspection for GTPv1-C and/or GTPv2-C automatically enables GTP-U stateful inspection. Enabling PFCP Stateful Inspection or Intelligent Security Correlation also enables GTP-U stateful inspection.

You can specify the following validity checks for GTP-U payloads and Block or Alert upon a validity check failure:

You can also allow, block or alert on:

Enable GTP-U Content Inspection if you want to inspect and apply policy to the user data payload within a GTP-U packet. Inspecting GTP-U content allows you to correlate IMSI and IMEI information learned from GTP-C messages with the IP traffic encapsulated in GTP-U packets.

For 5G, enable 5G-HTTP2 to enable inspection of 5G HTTP/2 control packets, which can contain subscriber IDs, equipment IDs, and network slice information. This allows you to correlate subscriber ID (IMSI), equipment ID (IMEI), and network slice ID information learned from HTTP/2 messages with the IP traffic encapsulated in GTP-U packets.

Enabling 5G-HTTP2 disables GTP-C for the profile and enables GTP-U.

For Packet Forwarding Control Protocol (PFCP), enable Stateful Inspection to inspect PFCP traffic. When you enable stateful inspection for PFCP traffic, the firewall inspects the traffic between the 5G core and the UPF to help prevent attacks such as Denial of Service (DOS) or spoofing. The UPF can be on the MEC site and the 5G Core can be in a central core site or the public cloud.

You can specify the following state checks:

You can then specify the Action (Allow, Alert, or Block) you want the firewall to take when the check is unsuccessful.

You can also select if you want the firewall to create a log at the beginning or ending of the PFCP associations or sessions.

Enables correlation between the subscriber ID and equipment ID to user equipment (UE) IP-based traffic for GTP-U content inspection.

Select the source that you want the firewall to use to correlate the control plane and user plane information for enforcement of subscriber-level and equipment-level Security policy. The firewall inspects traffic for the source type you select to process and extracts 5G/4G identity information, such as subscriber ID (SUPI or IMSI), equipment ID (PEI or IMEI), and the IP address of the user equipment (UE), to correlate with 5G/4G subscriber IP traffic.

Log UEIP correlation events when the firewall allocates an IP address to the UE.

Log UEIP correlation events when the firewall releases the allocated IP address.

By default all Radio Access Technologies (RAT) are allowed. GTP-C Create-PDP-Request and Create-Session-Request messages are filtered or allowed based on the RAT filter. You can specify whether to allow, block or alert on the following Remote Access Technologies (RAT) that the user equipment uses to access the mobile core network:

The following RATs are available when enabling 5G-HTTP2:

IMSI (International Mobile Subscriber Identity) is a unique identification associated with a subscriber in GSM, UMTS, and LTE networks that is provisioned in the Subscriber Identity Module (SIM) card.

An IMSI is usually presented as a 15-digit number (8 bytes), but can be shorter. IMSI has three parts:

The IMSI Prefix combines the MCC and MNC and allows you to allow, block, or alert on GTP traffic from a specific PLMN. By default all IMSI are allowed.

You can either manually enter or import a csv file with IMSI or IMSI prefixes into the firewall. The IMSI can include a wildcard, for example, 310* or 240011*. The firewall supports a maximum of 5,000 IMSI or IMSI prefixes.

The Access Point Name (APN) is a reference to a GGSN/ PGW that a user equipment requires to connect to the internet. The APN is composed of two parts:

By default all APNs are allowed. The APN filter allows you to allow, block, or alert on GTP traffic based on the APN value. GTP-C Create-PDP-Request and Create-Session-Request messages are filtered or allowed based on the rules defined for APN filtering.

You can manually add or import an APN filtering list into the firewall. The value for the APN must include the network ID or the domain name of the network (for example, example.com) and, optionally, the operator ID.

For APN filtering, the wildcard (*) allows you to match for all APN. A combination of * and other characters is not supported for wildcards. For example, internet.mnc* will be treated as regular APN and will not filter all entries that start with internet.mnc.

The firewall supports a maximum of 1,000 APN filters.

Allows you to limit the maximum number of GTP-U tunnels to a destination IP address, for example, to the GGSN. Range: 0 to 100,000,000 tunnels.

Specify the threshold at which the firewall triggers an alert when the maximum number of GTP-U tunnels to a destination has been established. A GTP log message of high severity is generated when the configured tunnel limit is reached.

The number of events that the firewall counts before it generates a log when the configured GTP tunnel limits are exceeded. This setting allows you to reduce the volume of messages logged. Default: 100; range: 1 to 100,000,000

Select the virtual system that serves as the Gi/ SGi firewall on your firewall. The Gi/ SGi firewall inspects the mobile subscriber IP traffic traversing the Gi/ SGi interface from the PGW/ GGSN to the external PDN (packet data network) such as the internet and secures internet access for mobile subscribers.

Overbilling can occur when a GGSN assigns a previously used IP address from the End User IP address pool to a mobile subscriber. When a malicious server on the internet continues to send packets to this IP address as it did not close the session initiated for the previous subscriber and the session is still open on the Gi Firewall. To disallow data from being delivered, whenever a GTP tunnel is deleted (detected by delete-PDP or delete-session message) or timed-out, the firewall enabled for overbilling protection notifies the Gi/ SGi firewall to delete all the sessions that belong to the subscriber from the session table. GTP Security and SGi/ Gi firewall should be configured on the same physical firewall, but can be in different virtual systems.

In order to delete sessions based on GTP-C events, the firewall needs to have all the relevant session information and this is possible only when you manage traffic from the SGi + S11 or S5 interfaces for GTPv2 and Gi + Gn interfaces for GTPv1 in the mobile core network.

Allows you to selectively enable logging of allowed GTPv1-C messages, if you have enabled Stateful Inspection for GTPv1-C. These messages generate logs to help you troubleshoot issues as needed. By default, the firewall does not log allowed messages. The logging options for allowed GTPv1-C messages are:

Allows you to include the user location information (as area code and Cell ID) in GTP logs.

Enables you to capture events.

Allows you to selectively enable logging of the allowed GTPv2-C messages, if you have enabled Stateful Inspection for GTPv2-C. These messages generate logs to help you troubleshoot issues as needed. By default, the firewall does not log allowed messages. The logging options for allowed GTPv2-C messages are:

Allows you to selectively enable logging of the allowed GTP-U messages, if you have enabled Stateful Inspection for GTPv2-C and/or GTPv1-C. These messages generate logs to help you troubleshoot issues as needed.

The logging options for allowed GTP-U messages are:

Enable this option to verify that the firewall is inspecting GTP-U PDUs. The firewall generates a log for the specified number of G-PDU packets in each new GTP-U tunnel. Range is 1 to 10; default is 1.

Enable this log setting to capture a GTP packet that is any of the following types of GTP event:

Select N11 to selectively enable logging of allowed N11 messages. N11 messages help you with troubleshooting and provide deeper visibility into the HTTP/2 messages exchanged over an N11 interface for different procedures. This field is available only if you enabled 5G-HTTP2 on the 5G-C tab in the Mobile Network Protection profile.