Policy Diff: Comparing and Auditing Security Policies

The Policy Diff feature in BIG-IP ASM/AWAF is used to compare two security policies to identify any differences between them. This is useful for auditing, troubleshooting, and ensuring consistency between the staging and production versions of security policies. It allows administrators to view and apply changes between policies, ensuring that similar functions are maintained across environments.

Key Features of Policy Diff

• Purpose: Used for auditing purposes to ensure that two policies have similar functions or to compare the staging version of a policy with the production version. It helps to identify and apply any differences between the two.

• Access Path: Navigate to Application Security > Security Policies > Policy Diff in the BIG-IP ASM/AWAF management interface.

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Policy Diff Requirements

To perform a policy comparison, the following conditions must be met:

1. Same BIG-IP System: The policies to be compared must reside on the same BIG-IP system.

2. Same Language Encoding: Both policies must have the same language encoding for the comparison to work correctly.

3. Same Protocol Configuration: The policies must be configured for the same protocol (either HTTP or HTTPS).

4. Same Case-sensitivity Configuration: The case-sensitivity setting must be identical for both policies.

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Working Modes of Policy Diff

There are several modes in which the Policy Diff feature can operate, each serving different purposes based on how you want to manage the changes between the policies:

1. Work on Copy

   • Description: In this mode, the policies being compared remain intact. The changes made during the comparison process will only be applied to copies of the original policies, leaving the original policies unchanged.

   • Use Case: This mode is ideal when you want to test changes without impacting the original policies. It’s a safer option for trial modifications before applying them to live systems.

2. Work on Original

   • Description: This mode directly modifies the original policies. Any differences identified in the comparison will be incorporated into the original policies without creating copies.

   • Use Case: This mode is useful when you're confident in the changes and want them to be applied immediately to the original policies, but it does carry a higher risk as the changes are not reversible unless manually backed up.

3. Make a Copy

   • Description: This mode works directly on the original policies, but it creates backup copies of those policies before overwriting their settings. This ensures that the original settings are preserved and can be restored if necessary.

   • Use Case: This mode is appropriate when you need to update policies but want to retain a backup in case the changes need to be rolled back. It’s a safer alternative to working on the original without creating any backups.

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Benefits of Using Policy Diff

• Consistency Verification: Ensures that the policies used in different environments (e.g., staging and production) are consistent, helping prevent potential misconfigurations.

• Audit Trail: Serves as a tool for auditing changes, ensuring compliance with security policies and providing an overview of adjustments made over time.

• Error Prevention: Helps identify discrepancies in security policy settings, reducing the likelihood of unintentional misconfigurations that could expose the application to risks.

• Change Management: Facilitates easier change management by allowing you to compare the current policy state with a previous version, enabling more controlled updates.

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Example Scenario for Using Policy Diff

Imagine you have a staging policy for a web application that you’ve been testing with new configurations. Before applying those configurations to your production policy, you use Policy Diff to compare the staging policy with the current production policy. This comparison allows you to identify the exact differences, and using the “Work on Copy” mode, you can test the changes in a duplicate policy without affecting the live system.

If the changes work as expected, you can then apply them to the production policy, either by using “Work on Original” or “Make a Copy”, depending on your level of confidence and the risk tolerance for making changes directly on production.

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Summary of Policy Diff Modes

Mode	Description	Use Case
Work on Copy	Compares policies and makes changes only to copies of the original policies, leaving the originals intact.	Ideal for testing changes without affecting originals.
Work on Original	Directly modifies the original policies without creating any backup.	Suitable when confident in changes and applying directly.
Make a Copy	Works on the original policies but saves backups before making any changes.	Best when you need a backup and want to apply changes to original policies.

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Using the Policy Diff feature properly allows administrators to fine-tune and safely update security policies while ensuring that the integrity of both staging and production environments is maintained.