Upon installation, Access Manager provides the URL Policy Agent service to define policies to protect HTTP URLs. This service allows administrators to create and manage policies through a policy enforcer or policy agent.
The Policy Agent is the Policy Enforcement Point (PEP) for a server on which an enterprise’s resources are stored. The policy agent is installed separately from Access Manager onto a web server and serves as an additional authorization step when a user sends a request for a web resource that exists on the protected web server. This authorization is in addition to any user authorization request which the resource performs. The agent protects the web server, and in turn, the resource is protected by the authorization plug-in.
For example, a Human Resources web server protected by a remotely-installed Access Manager might have an agent installed on it. This agent would prevent personnel without the proper policy from viewing confidential salary information or other sensitive data. The policies are defined by the Access Manager administrator, stored within the Access Manager deployment and used by the policy agent to allow or deny users access to the remote web server’s content.
The most current Access Manager Policy Agents can be downloaded from the Sun Microsystems Download Center.
More information on installing and administrating the policy agents can be found in the Sun Java System Access Manager Policy Agent 2.2 User’s Guide.
Policy is evaluated in no particular order although as they are evaluated, if one action value evaluates to deny, subsequent policies are not evaluated, unless the Continue Evaluation On Deny Decision attribute is enabled in the Policy Configuration service.
Access Manager Policy agents enforce decisions only on web URLs (http://... , or https//...). However, agents can be written using the Java and C Policy Evaluation APIs to enforce policy on other resources.
In addition, the Resource Comparator attribute in the Policy Configuration Service would also need to be changed from its default configuration to:
Alternately, providing an implementation such as LDAPResourceName to implement com.sun.identity.policy.interfaces.ResourceName and configuring the Resource Comparator appropriately would also work.
The process for protected web resources begins when a web browser requests a URL that resides on a server protected by the policy agent. The server’s installed policy agent intercepts the request and checks for existing authentication credentials (a session token).
If the agent has intercepted a request and validated the existing session token, the following process is followed.
If the session token is valid, the user is allowed or denied access. If the token is invalid, the user is redirected to the Authentication Service, as outlined in the following steps.
Assuming the agent has intercepted a request for which there is no existing session token, the agent redirects the user to the login page even if the resource is protected using a different authentication method.
If the resource matches the non-enforced list, configured at the agent, access is allowed.
The Naming Service returns locators for the policy service, session service and logging service.
The agent sends a request to the Policy Service to get policy decisions applicable to the user.
Based on the policy decisions for the resource being accessed, the user is either allowed or denied access. If advice on the policy decision indicates a different authentication level or authentication mechanism, the agent redirects the request to the Authentication Service until all criteria is validated.