Chapter 4 FortiOS Carrier : Configuring GTP on FortiOS Carrier : GTP support on the Carrier-enabled FortiGate unit : Protocol anomaly detection and prevention
  
Protocol anomaly detection and prevention
The FortiOS Carrier firewall detects and optionally drops protocol anomalies according to GTP standards and specific tunnel states. Protocol anomaly attacks involve malformed or corrupt packets that typically fall outside of protocol specifications. These packets are not seen on a production network. Protocol anomaly attacks exploit poor programming practices when decoding packets, and are typically used to maliciously impair system performance or elevate privileges.
FortiOS Carrier also detects IP address spoofing inside GTP data channel.
See “Configuring the Protocol Anomaly feature in FortiOS Carrier”.