Tap interfaces in Palo Alto Networks firewalls allow for passive monitoring of network traffic without impacting the flow of that traffic. This is achieved by connecting the firewall to a switch's SPAN or mirror port, enabling the firewall to receive a copy of the traffic for analysis.
Key Characteristics
Passive Monitoring:
Tap interfaces receive mirrored traffic, allowing for visibility into network applications and threats without being inline.
No Traffic Enforcement:
Since the firewall is not inline, it cannot block or modify traffic; it can only alert on detected threats.
Deployment Simplicity:
Tap mode can be implemented without changes to the existing network design.
Configuration Steps
Connect the firewall's tap interface to a switch port configured for SPAN or mirroring.
In the firewall's web interface, navigate to
Network > Interfaces
, select the desired interface, and set its type to
Tap
.
Assign the tap interface to a security zone (e.g., TapZone).
Create security profiles (e.g., antivirus, anti-spyware) with actions set to
alert
.
Define a security policy rule with both source and destination zones set to the tap zone, allowing all traffic and applying the security profiles.
Commit the configuration to activate tap mode monitoring.
Limitations
No Traffic Control:
The firewall cannot enforce policies (e.g., block traffic) in tap mode; it can only provide visibility.
Resource Considerations:
It's recommended to avoid combining tap mode monitoring with production traffic on the same firewall to prevent performance impacts.
Bandwidth Constraints:
Ensure that the tap interface's bandwidth matches the mirrored traffic to prevent packet loss.
Use Cases
Security Assessments:
Gain insights into network applications and potential threats without disrupting operations.
Compliance Monitoring:
Observe traffic patterns to ensure adherence to organizational policies.
Network Visibility:
Understand application usage and user behavior within the network.