Tunnel Content Inspection

The firewall can inspect the traffic content of cleartext tunnel protocols without terminating the tunnel:
Tunnel content inspection is for cleartext tunnels, not for VPN or LSVPN tunnels, which carry encrypted traffic.
You can use tunnel content inspection to enforce Security, DoS Protection, and QoS policies on traffic in these types of tunnels and traffic nested within another cleartext tunnel (for example, a Null Encrypted IPSec tunnel inside a GRE tunnel). You can view tunnel inspection logs and tunnel activity in the ACC to verify that tunneled traffic complies with your corporate security and usage policies.
All firewall models support tunnel content inspection for GRE, non-encrypted IPSec, and VXLAN protocols. Only firewalls that support GTP security support GTP-U tunnel content inspection—see the PAN-OS Releases by Model that Support GTP and SCTP Security in the Compatibility Matrix.

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