Tunnel Content Inspection Overview
Table of Contents
Expand All
|
Collapse All
Next-Generation Firewall Docs
-
PAN-OS 9.1 (EoL)
- PAN-OS 11.1 & Later
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
- PAN-OS 10.0 (EoL)
- PAN-OS 9.1 (EoL)
- Cloud Management of NGFWs
-
- Management Interfaces
-
- Launch the Web Interface
- Configure Banners, Message of the Day, and Logos
- Use the Administrator Login Activity Indicators to Detect Account Misuse
- Manage and Monitor Administrative Tasks
- Commit, Validate, and Preview Firewall Configuration Changes
- Export Configuration Table Data
- Use Global Find to Search the Firewall or Panorama Management Server
- Manage Locks for Restricting Configuration Changes
-
-
- Define Access to the Web Interface Tabs
- Provide Granular Access to the Monitor Tab
- Provide Granular Access to the Policy Tab
- Provide Granular Access to the Objects Tab
- Provide Granular Access to the Network Tab
- Provide Granular Access to the Device Tab
- Define User Privacy Settings in the Admin Role Profile
- Restrict Administrator Access to Commit and Validate Functions
- Provide Granular Access to Global Settings
- Provide Granular Access to the Panorama Tab
- Panorama Web Interface Access Privileges
-
- Reset the Firewall to Factory Default Settings
-
- Plan Your Authentication Deployment
- Configure SAML Authentication
- Configure Kerberos Single Sign-On
- Configure Kerberos Server Authentication
- Configure TACACS+ Authentication
- Configure RADIUS Authentication
- Configure LDAP Authentication
- Configure Local Database Authentication
- Configure an Authentication Profile and Sequence
- Test Authentication Server Connectivity
- Troubleshoot Authentication Issues
-
- Keys and Certificates
- Default Trusted Certificate Authorities (CAs)
- Certificate Deployment
- Configure the Master Key
- Export a Certificate and Private Key
- Configure a Certificate Profile
- Configure an SSL/TLS Service Profile
- Replace the Certificate for Inbound Management Traffic
- Configure the Key Size for SSL Forward Proxy Server Certificates
-
- HA Overview
-
- Prerequisites for Active/Active HA
- Configure Active/Active HA
-
- Use Case: Configure Active/Active HA with Route-Based Redundancy
- Use Case: Configure Active/Active HA with Floating IP Addresses
- Use Case: Configure Active/Active HA with ARP Load-Sharing
- Use Case: Configure Active/Active HA with Floating IP Address Bound to Active-Primary Firewall
- Use Case: Configure Active/Active HA with Source DIPP NAT Using Floating IP Addresses
- Use Case: Configure Separate Source NAT IP Address Pools for Active/Active HA Firewalls
- Use Case: Configure Active/Active HA for ARP Load-Sharing with Destination NAT
- Use Case: Configure Active/Active HA for ARP Load-Sharing with Destination NAT in Layer 3
- Refresh HA1 SSH Keys and Configure Key Options
- HA Firewall States
- Reference: HA Synchronization
-
- Use the Dashboard
- Monitor Applications and Threats
- Monitor Block List
-
- Report Types
- View Reports
- Configure the Expiration Period and Run Time for Reports
- Disable Predefined Reports
- Custom Reports
- Generate Custom Reports
- Generate the SaaS Application Usage Report
- Manage PDF Summary Reports
- Generate User/Group Activity Reports
- Manage Report Groups
- Schedule Reports for Email Delivery
- Manage Report Storage Capacity
- View Policy Rule Usage
- Use External Services for Monitoring
- Configure Log Forwarding
- Configure Email Alerts
-
- Configure Syslog Monitoring
-
- Traffic Log Fields
- Threat Log Fields
- URL Filtering Log Fields
- Data Filtering Log Fields
- HIP Match Log Fields
- IP-Tag Log Fields
- User-ID Log Fields
- Tunnel Inspection Log Fields
- SCTP Log Fields
- Authentication Log Fields
- Config Log Fields
- System Log Fields
- Correlated Events Log Fields
- GTP Log Fields
- Syslog Severity
- Custom Log/Event Format
- Escape Sequences
- Forward Logs to an HTTP/S Destination
- Firewall Interface Identifiers in SNMP Managers and NetFlow Collectors
-
- User-ID Overview
- Enable User-ID
- Map Users to Groups
- Enable User- and Group-Based Policy
- Enable Policy for Users with Multiple Accounts
- Verify the User-ID Configuration
-
- App-ID Overview
- App-ID and HTTP/2 Inspection
- Manage Custom or Unknown Applications
-
- Apply Tags to an Application Filter
- Create Custom Application Tags
- Workflow to Best Incorporate New and Modified App-IDs
- See the New and Modified App-IDs in a Content Release
- See How New and Modified App-IDs Impact Your Security Policy
- Ensure Critical New App-IDs are Allowed
- Monitor New App-IDs
- Disable and Enable App-IDs
- Safely Enable Applications on Default Ports
- Applications with Implicit Support
- Application Level Gateways
- Disable the SIP Application-level Gateway (ALG)
- Maintain Custom Timeouts for Data Center Applications
-
- Best Practices for Securing Your Network from Layer 4 and Layer 7 Evasions
- Set Up Antivirus, Anti-Spyware, and Vulnerability Protection
- Set Up File Blocking
- Prevent Brute Force Attacks
- Customize the Action and Trigger Conditions for a Brute Force Signature
- Enable Evasion Signatures
- Monitor Blocked IP Addresses
- Threat Signature Categories
- Create Threat Exceptions
- Custom Signatures
- Threat Prevention Resources
-
- Decryption Overview
-
- Keys and Certificates for Decryption Policies
- SSL Forward Proxy
- SSL Forward Proxy Decryption Profile
- SSL Inbound Inspection
- SSL Inbound Inspection Decryption Profile
- SSL Protocol Settings Decryption Profile
- SSH Proxy
- SSH Proxy Decryption Profile
- Decryption Profile for No Decryption
- SSL Decryption for Elliptical Curve Cryptography (ECC) Certificates
- Perfect Forward Secrecy (PFS) Support for SSL Decryption
- SSL Decryption and Subject Alternative Names (SANs)
- High Availability Support for Decrypted Sessions
- Decryption Mirroring
- Configure SSL Forward Proxy
- Configure SSL Inbound Inspection
- Configure SSH Proxy
- Configure Server Certificate Verification for Undecrypted Traffic
- Enable Users to Opt Out of SSL Decryption
- Temporarily Disable SSL Decryption
- Configure Decryption Port Mirroring
- Verify Decryption
-
- How Decryption Broker Works
- Layer 3 Security Chain Guidelines
- Configure Decryption Broker with One or More Layer 3 Security Chain
- Transparent Bridge Security Chain Guidelines
- Configure Decryption Broker with a Single Transparent Bridge Security Chain
- Configure Decryption Broker with Multiple Transparent Bridge Security Chains
- Activate Free Licenses for Decryption Features
-
- About Palo Alto Networks URL Filtering Solution
- How Advanced URL Filtering Works
- URL Filtering Use Cases
- Plan Your URL Filtering Deployment
- URL Filtering Best Practices
- Activate The Advanced URL Filtering Subscription
- Configure URL Filtering
- Test URL Filtering Configuration
- Log Only the Page a User Visits
- Create a Custom URL Category
- URL Category Exceptions
- Use an External Dynamic List in a URL Filtering Profile
- Allow Password Access to Certain Sites
- URL Filtering Response Pages
- Customize the URL Filtering Response Pages
- HTTP Header Logging
- Request to Change the Category for a URL
-
-
- Tap Interfaces
-
- Layer 2 and Layer 3 Packets over a Virtual Wire
- Port Speeds of Virtual Wire Interfaces
- LLDP over a Virtual Wire
- Aggregated Interfaces for a Virtual Wire
- Virtual Wire Support of High Availability
- Zone Protection for a Virtual Wire Interface
- VLAN-Tagged Traffic
- Virtual Wire Subinterfaces
- Configure Virtual Wires
- Configure an Aggregate Interface Group
- Use Interface Management Profiles to Restrict Access
- Virtual Routers
- Service Routes
- RIP
- Route Redistribution
-
- DNS Overview
- DNS Proxy Object
- DNS Server Profile
- Multi-Tenant DNS Deployments
- Configure a DNS Proxy Object
- Configure a DNS Server Profile
- Use Case 1: Firewall Requires DNS Resolution
- Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System
- Use Case 3: Firewall Acts as DNS Proxy Between Client and Server
- DNS Proxy Rule and FQDN Matching
- Dynamic DNS Overview
- Configure Dynamic DNS for Firewall Interfaces
-
- NAT Rule Capacities
- Dynamic IP and Port NAT Oversubscription
- Dataplane NAT Memory Statistics
-
- Translate Internal Client IP Addresses to Your Public IP Address (Source DIPP NAT)
- Enable Clients on the Internal Network to Access your Public Servers (Destination U-Turn NAT)
- Enable Bi-Directional Address Translation for Your Public-Facing Servers (Static Source NAT)
- Configure Destination NAT with DNS Rewrite
- Configure Destination NAT Using Dynamic IP Addresses
- Modify the Oversubscription Rate for DIPP NAT
- Reserve Dynamic IP NAT Addresses
- Disable NAT for a Specific Host or Interface
-
-
- Policy Types
- Policy Objects
- Track Rules Within a Rulebase
- Enforce Policy Rule Description, Tag, and Audit Comment
- Move or Clone a Policy Rule or Object to a Different Virtual System
-
- External Dynamic List
- Built-in External Dynamic Lists
- Configure the Firewall to Access an External Dynamic List
- Retrieve an External Dynamic List from the Web Server
- View External Dynamic List Entries
- Exclude Entries from an External Dynamic List
- Enforce Policy on an External Dynamic List
- Find External Dynamic Lists That Failed Authentication
- Disable Authentication for an External Dynamic List
- Register IP Addresses and Tags Dynamically
- Use Dynamic User Groups in Policy
- Use Auto-Tagging to Automate Security Actions
- CLI Commands for Dynamic IP Addresses and Tags
- Application Override Policy
- Test Policy Rules
-
PAN-OS 11.1 & Later
- PAN-OS 11.1 & Later
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
-
- Tap Interfaces
-
- Layer 2 and Layer 3 Packets over a Virtual Wire
- Port Speeds of Virtual Wire Interfaces
- LLDP over a Virtual Wire
- Aggregated Interfaces for a Virtual Wire
- Virtual Wire Support of High Availability
- Zone Protection for a Virtual Wire Interface
- VLAN-Tagged Traffic
- Virtual Wire Subinterfaces
- Configure Virtual Wires
- Configure a PPPoE Client on a Subinterface
- Configure an IPv6 PPPoE Client
- Configure an Aggregate Interface Group
- Configure Bonjour Reflector for Network Segmentation
- Use Interface Management Profiles to Restrict Access
-
- DHCP Overview
- Firewall as a DHCP Server and Client
- Firewall as a DHCPv6 Client
- DHCP Messages
- Dynamic IPv6 Addressing on the Management Interface
- Configure an Interface as a DHCP Server
- Configure an Interface as a DHCPv4 Client
- Configure an Interface as a DHCPv6 Client with Prefix Delegation
- Configure the Management Interface as a DHCP Client
- Configure the Management Interface for Dynamic IPv6 Address Assignment
- Configure an Interface as a DHCP Relay Agent
-
- DNS Overview
- DNS Proxy Object
- DNS Server Profile
- Multi-Tenant DNS Deployments
- Configure a DNS Proxy Object
- Configure a DNS Server Profile
- Use Case 1: Firewall Requires DNS Resolution
- Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System
- Use Case 3: Firewall Acts as DNS Proxy Between Client and Server
- DNS Proxy Rule and FQDN Matching
-
- NAT Rule Capacities
- Dynamic IP and Port NAT Oversubscription
- Dataplane NAT Memory Statistics
-
- Translate Internal Client IP Addresses to Your Public IP Address (Source DIPP NAT)
- Create a Source NAT Rule with Persistent DIPP
- PAN-OS
- Strata Cloud Manager
- Enable Clients on the Internal Network to Access your Public Servers (Destination U-Turn NAT)
- Enable Bi-Directional Address Translation for Your Public-Facing Servers (Static Source NAT)
- Configure Destination NAT with DNS Rewrite
- Configure Destination NAT Using Dynamic IP Addresses
- Modify the Oversubscription Rate for DIPP NAT
- Reserve Dynamic IP NAT Addresses
- Disable NAT for a Specific Host or Interface
-
- Network Packet Broker Overview
- How Network Packet Broker Works
- Prepare to Deploy Network Packet Broker
- Configure Transparent Bridge Security Chains
- Configure Routed Layer 3 Security Chains
- Network Packet Broker HA Support
- User Interface Changes for Network Packet Broker
- Limitations of Network Packet Broker
- Troubleshoot Network Packet Broker
-
- Enable Advanced Routing
- Logical Router Overview
- Configure a Logical Router
- Create a Static Route
- Configure BGP on an Advanced Routing Engine
- Create BGP Routing Profiles
- Create Filters for the Advanced Routing Engine
- Configure OSPFv2 on an Advanced Routing Engine
- Create OSPF Routing Profiles
- Configure OSPFv3 on an Advanced Routing Engine
- Create OSPFv3 Routing Profiles
- Configure RIPv2 on an Advanced Routing Engine
- Create RIPv2 Routing Profiles
- Create BFD Profiles
- Configure IPv4 Multicast
- Configure MSDP
- Create Multicast Routing Profiles
- Create an IPv4 MRoute
-
-
PAN-OS 11.2
- PAN-OS 11.2
- PAN-OS 11.1
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
- PAN-OS 10.0 (EoL)
- PAN-OS 9.1 (EoL)
- PAN-OS 9.0 (EoL)
- PAN-OS 8.1 (EoL)
- Cloud Management and AIOps for NGFW
End-of-Life (EoL)
Tunnel Content Inspection Overview
Your firewall can inspect tunnel content anywhere on
the network where you do not have the opportunity to terminate the
tunnel first. As long as the firewall is in the path of a GRE, non-encrypted
IPSec, GTP-U, or VXLAN tunnel, the firewall
can inspect the tunnel content.
- Enterprise customers who want tunnel content inspection can have some or all of the traffic on the firewall tunneled using GRE, VXLAN, or non-encrypted IPSec. For security, QoS, and reporting reasons, you want to inspect the traffic inside the tunnel.
- Service Provider customers use GTP-U to tunnel data traffic from mobile devices. You want to inspect the inner content without terminating the tunnel protocol, and you want to record user data from your users.
The firewall supports tunnel content inspection on Ethernet interfaces,
subinterfaces, AE interfaces, VLAN interfaces, and VPN and LSVPN
tunnel interfaces. (The cleartext tunnel that the firewall inspects
can be inside a VPN or LSVPN tunnel that terminates at the firewall,
hence a VPN or LSVPN tunnel interface. In other words, when the
firewall is a VPN or LSVPN endpoint, the firewall can inspect the
traffic of any non-encrypted tunnel protocols that tunnel content
inspection supports.)
Tunnel content inspection is supported in Layer 3, Layer 2, virtual
wire, and tap deployments. Tunnel content inspection works on shared
gateways and on virtual system-to-virtual system communications.

The preceding figure illustrates the two levels of tunnel inspection
the firewall can perform. When a firewall configured with Tunnel
Inspection policy rules receives a packet:
- The firewall first performs a Security policy check to determine whether the tunnel protocol (Application) in the packet is permitted or denied. (IPv4 and IPv6 packets are supported protocols inside the tunnel.)
- If the Security policy allows the packet, the firewall matches the packet to a Tunnel Inspection policy rule based on source zone, source address, source user, destination zone, and destination address. The Tunnel Inspection policy rule determines the tunnel protocols that the firewall inspects, the maximum level of encapsulation allowed (a single tunnel or a tunnel within a tunnel), whether to allow packets containing a tunnel protocol that doesn’t pass strict header inspection per RFC 2780, and whether to allow packets containing unknown protocols.
- If the packet passes the Tunnel Inspection policy rule’s match criteria, the firewall inspects the inner content, which is subject to your Security policy (required) and optional policies you can specify. (The supported policy types for the original session are listed in the following table).
- If the firewall instead finds another tunnel, the firewall recursively parses the packet for the second header and is now at level two of encapsulation, so the second tunnel inspection policy rule, which matches a tunnel zone, must allow a maximum tunnel inspection level of two levels for the firewall to continue processing the packet.
- If your rule allows two levels of inspection, the firewall performs a Security policy check on this inner tunnel and then the Tunnel Inspection policy check. The tunnel protocol you use in an inner tunnel can differ from the tunnel protocol you use in the outer tunnel.
- If your rule doesn’t allow two levels of inspection, the firewall bases its action on whether you configured it to drop packets that have more levels of encapsulation than the maximum tunnel inspection level you configured.
By default, the content encapsulated in a tunnel belongs to the
same security zone as the tunnel, and is subject to the Security
policy rules that protect that zone. However, you can configure
a tunnel zone, which gives you the flexibility to configure
Security policy rules for inside content that differ from the Security
policy rules for the tunnel. If you use a different tunnel inspection
policy for the tunnel zone, it must always have a maximum tunnel inspection
level of two levels because by definition the firewall is looking
at the second level of encapsulation.
The firewall doesn’t support a Tunnel Inspection policy rule
that matches traffic for a tunnel that terminates on the firewall;
the firewall discards packets that match the inner tunnel session.
For example, when an IPSec tunnel terminates on the firewall, don’t
create a Tunnel Inspection policy rule that matches the tunnel you
terminate. The firewall already inspects the inner tunnel traffic
so no Tunnel Inspection policy rule is needed.
Although tunnel content inspection works on shared gateways
and on virtual system-to-virtual system communications, you can’t
assign tunnel zones to shared gateways or virtual system-to-virtual
system communications; they are subject to the same Security policy
rules as the zones to which they belong.
Both the inner tunnel sessions and the outer tunnel sessions
count toward the maximum session capacity for the firewall model.
The following table indicates with a check mark which types of
policy you can apply to an outer tunnel session, an inner tunnel
session, and the inside, original session:
Policy Type | Outer Tunnel Session | Inner Tunnel Session | Inside, Original Session |
---|---|---|---|
App-Override | ![]() VXLAN
Only | ![]() | ![]() |
DoS Protection | ![]() | ![]() | ![]() |
NAT | ![]() | ![]() | ![]() |
Policy-Based Forwarding (PBF) and Symmetric
Return | ![]() | ![]() | ![]() |
QoS | ![]() | ![]() | ![]() |
Security (required) | ![]() | ![]() | ![]() |
User-ID | ![]() | ![]() | ![]() |
Zone Protection | ![]() | ![]() | ![]() |
VXLAN is different than other protocols. The firewall can use
either of two different sets of session keys to create outer tunnel
sessions for VXLAN.
- VXLAN UDP Session—A six-tuple key (zone, source IP, destination IP, protocol, source port, and destination port) creates a VXLAN UDP Session.
- VNI Session—A five-tuple key that incorporates the tunnel ID (the VXLAN Network Identifier, or VNI) and uses zone, source IP, destination IP, protocol, and tunnel ID (VNI) to create a VNI Session.
You can View
Inspected Tunnel Activity on the ACC or View
Tunnel Information in Logs. To facilitate quick viewing,
configure a Monitor tag so you can monitor tunnel activity and filter
log results by that tag.
The ACC tunnel activity provides data in various views. For the
Tunnel ID Usage, Tunnel Monitor Tag, and Tunnel Application Usage,
the data for bytes, sessions, threats, content,
and URLs come from the Traffic Summary database.
For the Tunnel User, Tunneled Source IP and Tunneled Destination
IP Activity, data for bytes and sessions come
from Traffic Summary database, data for threats come
from the Threat Summary, data for URLs come
from the URL Summary, and data for contents come
from the Data database, which is a subset of the Threat logs.
If you enable NetFlow on the interface, NetFlow will capture
statistics for the outer tunnel only, to avoid double-counting (counting
bytes of both outer and inner flows).
For the Tunnel Inspection policy rule and tunnel zone capacities
for your firewall model, see the Product Selection tool.
The following figure illustrates a corporation that runs multiple
divisions and uses different Security policies and a Tunnel Inspection
policy. A Central IT team provides connectivity between regions.
A tunnel connects Site A to Site C; another tunnel connects Site
A to Site D. Central IT places a firewall in the path of each tunnel;
the firewall in the tunnel between Sites A and C performs tunnel
inspection; the firewall in the tunnel between Sites A and D has
no tunnel inspection policy because the traffic is very sensitive.
