NetScaler Gateway

Using Advance Policy to Create VPN Policies

Classic Policy Engine (PE) and Advance Policy Infrastructure (PI) are two different policy-configuration-and-evaluation frameworks that NetScaler currently supports.

Advance Policy Infrastructure consists of extremely powerful expression language. The expression language can be used to define Rules in Policy, define various parts of Action, and other entities supported. The expression language can parse through any part of the request or response and also enables you to look deeply through the headers and payload. The same expression language expands and works through every logical module NetScaler supports.

Note: You are encouraged to use advanced policies for creating policies.

Why Migrate from Classic Policy to Advance Policy

Advanced Policy has a rich expression set and offers much greater flexibility than Classic Policy. As NetScaler scales and caters to vast variety of clients, it is imperative to support expressions which vastly exceed the Advanced Policies. For more information, see Policies and Expressions topic.

Following are the added capabilities for Advance Policy.

  • Ability to access the body of the messages.
  • Supports many additional protocols.
  • Accesses many additional features of the system.
  • Has more number of basic functions, operators, and data types.
  • Caters to the parsing of HTML, JSON, and XML files.
  • Facilitates fast parallel multi-string matching (patsets, etc.).

Now the following VPN policies can be configured using Advance Policy.

  • Session Policy
  • Authorization Policy
  • Traffic Policy
  • Tunnel Policy
  • Audit Policy

Also, End Point Analysis (EPA) can be configured as an nFactor for authentication feature. EPA is used as a gatekeeper for endpoint devices trying to connect to the Gateway appliance. Before the Gateway logon page is displayed on an endpoint device, the device is checked for minimum hardware and software requirements, depending on the eligibility criteria configured by Gateway administrator. The access to Gateway is granted based on the outcome of the performed checks. Previously EPA was configured as part of session policy. Now it can be linked to nFactor providing more flexibility, as to when it can be performed. For more information on EPA, see How endpoint policies work topic. For more on nFactor, see nFactor authentication topic.

Use Cases:

Pre-authentication EPA using Advanced EPA

Pre-authentication EPA scan happens before user provides the logon credentials. For information on configuring NetScaler Gateway for nFactor authentication with pre-authentication EPA scan as one of the authentication factors, see CTX224268 topic.

Post-auth EPA using Advanced EPA

Post-authentication EPA scan happens after user credentials are verified. Under classic policy infrastructure, post authentication EPA was configured as part of the session policy or session action. Under Advanced policy infrastructure, EPA scan is to be configured as EPA factor in n-factor authentication. For information on configuring NetScaler Gateway for n-factor authentication with post-authentication EPA scan as one of the authentication factors, see CTX224303 topic.

Pre-authentication and post-authentication EPA using Advanced policies

EPA can be performed before authentication and post authentication. For information on configuring NetScaler Gateway for nFactor authentication with pre-authentication and post-authentication EPA scans, see CTX231362 topic.

Periodic EPA scan as a factor in nFactor authentication

Under Classic policy infrastructure, periodic-EPA scan was configured as part of session policy action. Under advanced policy infrastructure, it can be configured as part of EPA factor in n-factor authentication.

For more information on configuring Periodic EPA scan as a factor in nFactor authentication, click CTX231361 topic.

Troubleshooting: The following points are to be kept in mind for troubleshooting.

  • Classic and Advance policies of the same type (for example, Session policy) cannot be bound to the same entity/bind point.
  • Priority is mandatory for all of the PI policies.
  • Advance Policy for VPN can be bound to all bind points.
  • Advance Policy with same priority can be bound to a single bind point.
  • If none of the configured authorization policies get hit then the global authorization action configured in VPN parameter is applied.
  • In authorization policy, the authorization action is not reversed if the authorization rule fails.

Commonly used Advanced Policy equivalent expressions for Classic Policy:

Classic Policy expressions Advance Policy expressions
ns_true true
ns_false false
HEADER “foo” HEADER(“foo”)
CONTAINS ”bar” .CONTAINS(“bar”) [Note use of “.”.]