Cisco Cisco Firepower Management Center 4000

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FireSIGHT System User Guide
 
23 
Using Layers in an Intrusion Policy
Larger organizations with many managed devices may have many intrusion policies to support the 
unique needs of different departments, business units or, in some instances, different companies. The 
rule settings and advanced settings in an intrusion policy are contained in building blocks called policy 
layers, which you can use to more efficiently manage multiple policies.
You can create and edit a policy without consciously using layers. You can modify rule settings and 
advanced settings and, if you have not added user layers to your policy, the system automatically 
includes your changes in a single configurable layer. Optionally, you can also add up to 200 layers where 
you can configure any combination of rule settings and advanced settings. You can copy, merge, move, 
and delete user layers and, most importantly, share individual user layers with other policies.
See the following sections for more information:
  •
 explains the layers that comprise a basic policy 
and how you can use them.
  •
 explains how you can add, copy, merge, and share 
user-configurable layers, and how to view and access the configuration pages for rules and advanced 
settings.
Understanding Intrusion Policy Layers
License: 
Protection
A policy where you do not add layers includes the read-only base policy layer and a single 
user-configurable layer that is initially named My Changes. If you generate and use rule state 
recommendations based on network discovery data, the system automatically inserts a read-only 
FireSIGHT Recommendations layer immediately above the base policy. You can copy, merge, move, or 
delete any user-configurable layer and set any user-configurable layer to be shared by other intrusion 
policies; note that the My Changes layer is a user-configurable layer.
Each policy layer contains complete settings for all intrusion rules, preprocessor rules, and advanced 
settings. The layer at the bottom of the stack includes all the settings from the base policy you selected 
when you created the policy. A setting in a higher layer in the policy layer stack takes precedence over 
the same setting in a lower layer. Features not explicitly set in a layer inherit their settings from the next 
highest layer below where they are explicitly set.
The following figure shows an example intrusion policy layer stack that, in addition to the base policy 
layer and the initial My Changes layer, also includes two additional user-configurable layers and the 
FireSIGHT Recommendations layer. Note in the figure that each user-configurable layer that you add is 
initially positioned as the highest layer in the stack; thus, User Layer 2 in the figure was added last and 
is highest in the stack.