Configure Decryption Broker with a Single Transparent Bridge Security Chain

Perform the following steps to enable the firewall to act as a decryption broker that distributes traffic to a Transparent Bridge Security Chain for additional analysis and enforcement. Enabling the firewall as a decryption broker includes:
  • Set up a Transparent Bridge security chain that adheres to the Transparent Bridge Security Chain Guidelines.
  • Activate the free decryption broker license (Decryption Licenses). This includes going to the Palo Alto Networks Customer Support Portal to activate the license, and then installing the license on the firewall.
  • Enable a pair of Layer 3 firewall interfaces as decryption forwarding interfaces. Each pair of decryption forwarding interfaces supports one transparent bridge security chain; you’ll need to create multiple decryption forwarding interface pairs to support multiple Transparent Bridge security chains.
  • Configure a Decryption Forwarding profile to enable the firewall to forward decrypted sessions to a Transparent Bridge security chain and to monitor security chain performance.
Even if you plan to enable decryption broker with multiple Transparent Bridge security chains, you must perform the following steps first.
  1. Set up a Transparent Bridge security chain following the Transparent Bridge Security Chain Guidelines.
  2. Activate the free Decryption Broker license (see Decryption Licenses).
  3. Confirm that the firewall is enabled to perform SSL Forward Proxy decryption.
    Select
    Policies
    Decryption
    to
    Add
    or modify a decryption policy rule. You can also attach a decryption profile to a decryption policy rule, to perform certificate checks and validate SSL protocols. For example, a decryption profile allows you to block sessions based on certificate status, using unsupported protocols or cipher suits, or if the resources to perform decryption are not available.
  4. Enable a pair of Layer 3 interfaces to forward decrypted traffic.
    1. View configured interfaces on the
      Network
      Interfaces
      Ethernet
      tab.
      The Interface Type column displays if an interface is configured as a Layer 3 interface. Select a Layer 3 interface and complete the following steps for both Layer 3 interfaces that you want to enable as a Decrypt Forward pair.
    2. Select the
      Config
      tab and assign the interface to a
      Virtual Router
      that has no configured routes or interfaces used to pass dataplane traffic.
      The virtual router must be dedicated to the decryption forwarding interfaces to ensure the clear text sessions that the firewall forwards for additional analysis are totally segmented from dataplane traffic.
    3. Continue to assign the interface to a
      Security Zone
      . (Assign both interfaces to the same security zone).
    4. On the
      Advanced
      tab, select
      Decrypt Forward
      .
    5. Click
      OK
      to save the interface settings.
    6. Repeat these steps so that at least two interfaces are enabled to forward decrypted traffic.
      A pair of two decryption forwarding interfaces supports a single Transparent Bridge Security Chain. If you want the firewall to distribute decrypted sessions amongst multiple Transparent Bridge security chains, continue to enable a pair of decryption forwarding interfaces for each security chain you want to support.Make sure that the interfaces enabled to forward decrypted traffic are not being used to pass any other type of traffic.
  5. Create a Decryption Forwarding profile to define settings for the firewall to forward decrypted traffic to a Transparent Bridge security chain.
    1. Select
      Objects
      Decryption
      Forwarding Profile
      ,
      Add
      a new Decryption Forwarding Profile, and give the profile a descriptive
      Name
      .
    2. On the
      General
      tab, set the
      Security Chain Type
      to
      Transparent Bridge
      to configure the firewall to forward decrypted traffic to a security chain with Transparent Bridge devices.
    3. Set the
      Flow Direction
      for decrypted traffic the firewall forwards:
      Unidirectional
      or
      Bidirectional
      .
    4. Select the
      Primary Interface
      and
      Secondary Interface
      the firewall uses to forward traffic to the security chain.
      Together, the primary and secondary interfaces form a pair of decryption forwarding interfaces. Only interfaces that you have enabled to be Decrypt Forward interfaces are displayed here.
  6. Select the
    Health Monitor
    tab to enable the firewall to perform health checks on a Transparent Bridge security chain.
    1. On
      Health Check Failure
      , set the firewall to
      Block Session
      .
      Because Transparent Bridge security chain session distribution is policy-based, traffic cannot bypass a failed security chain, as the traffic matched to a policy rule is assigned to a specific chain for inspection.
    2. Define a
      Health Check Failed Condition
      as an event where any of the health monitor conditions are met (an
      OR Condition
      ), or when all of the conditions are met (an
      AND Condition
      ).
    3. Enable
      Path Monitoring
      ,
      HTTP Latency Monitoring
      , and/or
      HTTP Monitoring
      . For each type of monitoring you want to enable, define the periods of time and/or counts that you want to trigger a health check failure.
      Latency and HTTP monitoring are required to effectively support Lowest Latency session distribution (
      Objects
      Decryption
      Forwarding Profile
      Security Chains
      Session Distribution Method
      ).
  7. Save the Forwading Profile.
  8. Attach the Forwarding Profile to a decryption policy rule.
    The firewall decrypts and inspects traffic the rule matches, and then forwards the clear text traffic to the security chain for further inspection and enforcement.
    1. Select
      Policies
      Decryption
      and select a decryption policy rule.
    2. Use the policy rule tabs to define the traffic that you want to forward to the associated Transparent Bridge security chain.
      For example, select
      Source
      and
      Add
      a
      Source Address
      range, or click
      New Address
      to create an address objects that identifies traffic originating from a given IP address range. The policy rule will enforce only traffic that originates from this source.
    3. Select
      Options
      .
    4. Set the
      Action
      to
      Decrypt and Forward
      .
    5. Select a
      Transparent Bridge Forwarding Profile
      .
    6. Click
      OK
      to save the policy rule and
      Commit
      your changes.
  9. Monitor the decrypted traffic that the firewall has forwarded for additional inspection.
    • Select
      Monitor
      Logs
      Traffic
      and add the filter:
      (flags has decrypt-forwarded)
      .
    • Check the details for a traffic log entry and look for the Decrypt Forwarded flag.

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