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Examples of Admission Control Uses

Businesses might use the following examples as part of future security policies for NAC to enforce. Some of these capabilities exist today in partner vendor products, while others require some development. All are possible with the use of custom applications that can plug into the NAC framework:

  • Track and manage company assets
  • Enforce the use of corporate-approved software
  • Enforce operating system access control
  • Enforce physical identification for higher security clearance
  • Enforce a business policy or rule
  • Enforce regulatory compliance
  • Enact roles-based provisioning
  • Enforce data restriction when external media is detected
  • Use customized shared resources

The following sections cover these uses.

Tracking and Managing Company Assets

When a device is detected by the network, the serial number is checked with a policy server and a back-end database for validation. Only company-owned assets are allowed access to the network. If the host is assigned to a user, only the assigned user can successfully log in to the host computer. In addition, the database can be updated to provide a general location of where the host is logged in or was last logged in. The location can be determined by the NAD servicing it.

Enforcing Use of Corporate-Approved Software

Ensure that the host is running corporate-approved software (for example, corporate image). This could be determined by the host identity, such as the serial number, or by user identity. Use NAC to limit network access to users whose hosts are not running corporate-sanctioned software or image, regardless of application.

Enforcing Operating System Access Control

Protect operating system integrity by prohibiting access or changes to sensitive system files, system binaries, and registry settings. An example is to allow basic actions required by the operating system process but to prevent file manipulation by users or applications from the Windows system directory. Enforce the host firewall or require the use of Windows IPsec filtering to control the type of traffic, such as a shared server or PC, that reaches a host. A HIPS such as CSA can provide this type of hardening capability today. Use NAC to enforce an OS-hardening policy before the host is allowed access to the network.

Enforcing Physical Identification for Higher Security Clearance

For an extra layer of defense, add a physical authentication requirement to associate a specific host to a specific user when the user attempts to access extremely confidential information. The technology could use a portable USB smart token or even a biometric device to perform physical identification verification (PIV). The PIV device could scan and verify a user’s fingerprint, palm, or even eye. An example of physical identification enforcement is where an admission policy requires a portable USB secure token to be present in the host that is attempting network access. The secure token requires a valid personal identification number (PIN) to be entered by the user for the host’s security application to initiate the NAC validation process. After being successfully authenticated with this physical identity credential, the user gets more privileges assigned with a higher security clearance from the policy server. This higher privilege remains active until the assigned time period expires or until the USB secure token is removed. NAC has configurable timers and/or uses EAP over LAN–Start (EAPoL-Start) with 802.1X to verify that the device is still compliant with the existing security policy. It can detect when a change occurs. Another option is to have the host application reinitiate the NAC process when it detects a change, such as removing the USB token, to lower the user’s security clearance.

Enforcing a Business Policy or Rule

Your business might have rules for users that can be automated for a quick, consistent resolution. An example is a user that requires manager approval to access a certain server or file or to download company-provided software. The user who needs permission attempts access but is denied. However, the user can be automatically redirected to an application to submit the request. After the request is submitted, it is automatically routed electronically to the user’s manager for approval and allows an expiration period to be assigned to this privilege. After approval is gained, the policy server raises the user’s access privilege for a period of time and notifies the user by means of a pop-up or e-mail message that access to the server or file is now available.

Enforcing Regulatory Compliance

Some businesses must comply with industry or government regulations, such as the Gramm-Leach-Bliley Act (GLBA), the Sarbanes-Oxley (SOX) Act, and the Health Insurance Portability and Accountability Act (HIPAA). NAC can enforce features such as password control, identifying the user, and allowing only those users with the proper identity to access business- or client-sensitive information. You could enforce a user’s PC to initiate the built-in screen saver after ten minutes of inactivity. You could even guarantee that a password setting is used to regain the display. Extra steps such as these can automatically ensure that the host is secure, even when the user steps away. Use NAC to enforce PC functions such as this by means of a custom API that detects the settings and sends credentials to a policy server that enforces compliance.

Enacting Roles-Based Provisioning

Policy based on job type or device type provides a consistent set of common rules or privileges organized by groups. Privileges can include network access rights, file read/write privileges, common use of software or web applications, work time, and day schedule. When changes are made to the role, it provides a quick and consistent policy change to a common group of users/hosts. Use NAC to enforce a policy to a user or host from a policy server that controls access to a variety of resources. If role privileges are changed, the policy server can initiate a revalidation of those users who require enforcement of the new policy.

Enforcing Data Restriction When External Media Is Detected

Controlling read/write access to sensitive information with removable media can prevent loss of business-sensitive information or client financial or health data. An example is an application on a host that detects whether an external storage device, such as USB flash drive or external drive, is present. The host initially authenticated successfully when the device was not present. A host’s application detects a change and initiates a NAC revalidation with the policy server. New credentials are sent. The admission policy for the device has changed and does not allow removable USB storage devices. It denies the user access to certain areas of the network, or it can prevent the downloading of certain types of files tagged as confidential, such as patient records. The offending host is not allowed to access the restricted area or perform downloads while the external device is present. When the external storage device has been removed from the host, the application detects this and a revalidation reoccurs. The policy server now grants full read/write access to the host and user. NAC works with other software applications to enforce policy and report user activity (for example, if a user attempts to save files tagged confidential to his host’s hard drive without the external device plugged in and then transfers the files to the storage device later). The security software application such as CSA can be programmed by a user’s profile to prevent the transfer of files to the hard drive and/or report this type of event.

Using Customized Shared Resources

Some businesses have a 24/7 multiple-shift operation in which employees share common resources, including desks, host computers, and telephones. Each work shift, an employee picks a free desk and successfully logs in to a host, which is associated with a phone and a desk. The user’s identity is associated with a virtual machine that has personal settings and assigned applications with access to his personal files. The IP phone is configured for extension mobility, allowing the user to log in and activate his personal extension, feature buttons, and voice-mail settings to that phone. The desk has been checked out to the user and is logged as being unavailable for others to use. During the employee’s work shift, his desk devices are personalized for his use. An auditing system keeps track of where the employees work, the hours worked, and the resources they use. This can serve to track usage for department billing and accounting for payroll use, and serve as a measurement for historical trends reporting. At the end of his shift, the user logs off the host and phone, which restores him to a defaulted guest access state, waiting for the next shift. Use NAC to associate an authorized user, host, and applications together, especially for users who do not have dedicated devices. Enforce software compliance and secure file access in this virtual environment.

These examples are just a sample of what can become part of your admission policy decision to help you police your information highway. Advanced identity and compliance capabilities can exist by including NAC-enabled vendor applications. Even if you don’t need these advanced capabilities today, be assured that when you implement the Cisco NAC Framework, it sets the foundation to flexibly add a variety of future enforcement decisions to your network admission policy.

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