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12:58 AM
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Chapter 13. Troubleshooting Cisco Secure ACS on Windows

Cisco Secure Access Control Server, which is known as CS ACS, fills the server-side requirement of the Authentication, Authorization, and Accounting (AAA) client server equation. For many security administrators, the robust and powerful AAA engine, along with CS ACS's ability to flexibly integrate with a number of external user databases, makes the CS ACS software the first and sometimes only choice for an AAA server-side solution. This chapter explores CS ACS in detail and walks you through troubleshooting steps. The chapter focuses on the approach required to troubleshoot any issue efficiently, either with the CS ACS software itself or with the whole AAA 

Overview of CS ACS

Before delving into the details of how an AAA request from a network access server (NAS) is processed by CS ACS, you need a good understanding of all the components that bring the Cisco Secure ACS into existence.

CS ACS Architecture

As shown in Figure 13-1, Cisco Secure ACS comprises a number of services.
  • CSAdmin This service provides the Web interface for administration of Cisco Secure ACS. Although it is possible, and sometimes desirable, to use the Command Line Interface (CLI) for CS ACS configuration, the Graphical User Interface (GUI) is a must because certain attributes may not be configured via CLI. In addition, with the GUI, the administrator has little or no chance to insert bad data, which could lead to database corruption, because the GUI has a sanity check mechanism for user data insertion. The web server used by CS ACS is Cisco proprietary and uses TCP/2002 rather than the standard port 80. Therefore, another web server may be running on the CS ACS server, but this is not recommended because of the security risk and other possible interference.
    Because CSAdmin service is coded as multi-threaded, it is possible to open multiple sessions from different locations to the CS ACS Server for configuration purposes, but CS ACS does not allow making the same profile or attribute changes by multiple administrators at the same time. For instance, group 200 may not be modified by two administrators at the same time. You need to create an admin account to allow remote access to CS ACS from another machine; you do not need the admin account, however, if you access it from the CS ACS server itself. To bring up the CS ACS GUI from a host other than CS ACS, point to the following location:
    http://:2002
    
    All the services except CSAdmin can be stopped and restarted from the GUI (System > Service Control>Stop/Restart). CSAdmin can be controlled via a Windows Services applet, which can be opened by browsing to Start > Programs > Administrative Tools > Services applet.
  • CSAuth CSAuth is the heart of CS ACS server, which processes the authentication and authorization requests from the NAS. It also manages the Cisco Secure CS ACS database.
  • CSDBSync CSDBSync is the database synchronization service, which allows the CS ACS database to be in sync with third-party relational database management system (RDBMS) systems. This feature is very useful when an organization has multiple data feed locations.
  • CSLog This is a logging service for audit-trailing, accounting of authentication, and authorization packets. CSLog collects data from the CSTacacs or CSRadius packet and CSAuth, and then scrubs the data so that data can be stored into comma-separated value (CSV) files or forwarded to an Open DataBase Connectivity (ODBC)-compliant database.
  • CSMon CSMon service is responsible for the monitoring, recording, and notification of Cisco Secure CS ACS performance, and includes automatic response to some scenarios. For instance, if either Terminal Access Controller Access Control System (TACACS+) or Remote Authentication Dial-In User Service (RADIUS) service dies, CS ACS by default restarts all the services, unless otherwise configured. Monitoring includes monitoring the overall status of Cisco Secure ACS and the system on which it is running. CSMon actively monitors three basic sets of system parameters:
    - Generic host system state monitors disk space, processor utilization, and memory utilization.
    - Application-specific performance periodically performs a test login each minute using a special built-in test account by default.
    - System resource consumption by Cisco Secure ACS CSMon periodically monitors and records the usage by Cisco Secure ACS of a small set of key system resources. Handles counts, memory utilization, processor utilization, thread used, and failed log-on attempts, and compares these to predetermined thresholds for indications of atypical behavior.

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