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Troubleshooting Cisco Secure ACS on Windows

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Jun 16, 2006.

Chapter Description

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 process.

Common Problems and Resolutions

This section examines some of the commonly encountered problems that were not discussed earlier.

  1. I am getting "Crypto Error" while trying to install/upgrade CS ACS. How do I fix this?

    Answer: Use an administrator account when performing the installation.

    Rename the pdh.dll file in the system32 directory.

    The problem lies in MS CryptoAPI settings. If you remove or customize Internet Explorer or install any security patches, the IE updates and security updates often distribute modified CryptoAPI files. Installing these can sometimes break existing CryptoAPI clients. You might also receive this error message if the CS ACS services are being run as another user (or were installed as another user) or if the file permissions to the CryptoAPI data do not permit access. If nothing has changed on IE, follow these steps:

    1. Uninstall CS ACS.
    2. Search the Documents and Settings folder for any files with CiscoSecure ACS in the file name; they will be in a user's Application Data\Microsoft\Crypto\RSA folder.
    3. If found, delete the CS ACS file.
    4. Search the Registry for a key named CiscoSecure ACS v2.0 Container.
    5. If found, delete the key. This removes any existing CiscoSecure CryptoAPI references. Now try to reinstall.

    Uninstalling CS ACS manually:

    1. Under HKEY_LOCAL_MACHINE\SOFTWARE\CISCO, delete the Cisco\CiscoAAAvX Registry tree.
    2. From the same location, delete the directory.
    3. Then go to Services applet and make sure none of the seven services for CS ACS are listed there.
    4. If the services are installed and show up in the service list, there are entries in the Registry for them. Search the Registry for Cisco and selectively delete the keys and values.
  2. What can I do when my Registry of CS ACS is corrupted?

    Answer: It is a good idea to back up the Registry of Windows when it is clean, before even installing the CS ACS software, so that it can be imported back if the Registry is corrupted and the CS ACS needs to be reinstalled.

    Execute the clean.exe utility on the CS ACS CD.

  3. What can I do when I get the following error when upgrading from an older to a newer version?

    "The old installation folder appears to be locked by another application:

    c:\Program Files\CiscoSecureACSv3.X

    Please close any applications that are using any files or directories in this folder and re-run setup."

    Answer: Get a dump.txt, uninstall, reinstall, and reconfigure NAS only if you have a small number of NASs. If you have a large number of NASs, this may not work.

    Reboot the server to ensure that it is not locked up by other applications.

    Are there any shared directories on the CS ACS machine?

    If you are installing remotely via either VNC or "Terminal Services" or "Remote Desktop", try installing locally.

    If you must install remotely, try installing by using Control Panel > Add/Remove Programs (then browse to setup.exe). This helps occasionally when using a terminal service connection.

    If the problem still persists, download the Filemon utility from the following location and run it while the installation is getting the error.


    Filemon captures all file activity and shows the error code, so you can see which particular file is causing trouble with the install shield. You may also find out which process is locking the file by using the Handle tool that can be downloaded from the following location.


    Killing the process and deleting the file may resolve the issue.

    You may want to turn on the Manage Log Directory option under System Config > Service Control and System Config > Logging > <all CSV logs>. During an upgrade under some circumstances, this may fix the message stating that the folder is locked.

  4. I am trying to upgrade a CS ACS that is installed under D: drive, but am having problems with space issues under C:. Why?

    Answer: When performing a clean install, the Installation Wizard gives you the option of choosing the location in which you want to install the CS ACS software. However, this option is not available for upgrades. For example, when you try to upgrade by running the new version of CS ACS setup.exe, the Installation Wizard drops the new version on the C: drive. So, whenever the installation process finds a previous configuration and prompts the user to keep the existing database and configuration, you do not have the option of selecting an installation location. Whenever the installation process is clean and the user is not prompted to keep the existing database and configuration, you will have the option of selecting a different installation location. This might create a problem if the C: drive is low in space. To get around the problem, the only option available is to create more disk space on the C: drive.

  5. What's the minimum CS ACS version requirement for MS-CHAP v2 support?

    Answer: The minimum requirement is version CS ACS 3.0.

    1. Is it possible to force the user to provide login credentials when trying to launch the CS ACS Windows Admin GUI from the CS ACS Server itself locally?

      Answer: Yes, it is possible. If you have allowAutoLocalLogin set to 1 in the Registry, you do not need to provide login credentials. So to force the user to provide login credentials if accessing CS ACS locally, change value for allowAutoLocalLogin to 0. To find out this key, you can search using this keyword.

    2. If I lose the admin password to get into the GUI, how can I recover it?

      Answer: By default, the CS ACS does not require you to provide login credentials if you are accessing it locally from the CS ACS server itself. However, if you force local login by un-checking the Allow automatic local login check box under Administration Control > Session Policy (this essentially sets the allowAutoLocalLogin in the Registry to 0 as discussed in question 6), and you lose the admin password, the best solution is to set the allowAutoLocalLogin to 1. Then you can log in to the CS ACS locally from the server and add or modify administrators. The Registry location for the allowAutoLocalLogin is as follows:

    3. Under the Security key, you can modify allowAutoLocalLogin by right-clicking and choosing modify. How can I set up a default NAS so that I do not have to create multiple AAA clients on CS ACS for every NAS that uses the same shared secret key?

      Answer: You can add a default NAS in the NAS configuration area by leaving the host name and IP address blank. Put in only the key. Click Submit, and you will see NAS others and *.*.*.*. Note that this works only for TACACS+, not RADIUS.

    4. Which registries pertain to the CS ACS Server?

      Answer: HKEY_local_machine\software\cisco\CiscoAAAv3.x and HKEY_local_ machine\software\cisco\CiscoSecureACSv3.x

    5. I want to use TACACS+ for router management and one RADIUS for dial on the same CS ACS Server. Is it possible? How?

      Answer: Yes, it is possible. Just configure the NAS method lists for login authentication with TACACS+ and PPP authentication with RADIUS. On CS ACS, just define two AAA clients with the same IP, different names and different protocols (TACACS+ and RADIUS).

    6. How do I capture debugs for Cisco to use to troubleshoot my issue?

      Answer: On CS ACS GUI, select System configuration > Service control and set logging to FULL. Then in the section underneath, select Manage Logs so that they do not grow out of control. Then wait until AAA fails again and the logs on the server are collected by running cssupport.exe from the command-line. This is found in the utils directory in the Cisco Secure ACS directory.

    7. How do I find the exact release of Cisco Secure ACS?

      Answer: There are two ways of checking:

      First, when you bring up the browser, look for the following at the bottom of the page: 

      CiscoSecure ACS
      !The following line indicates the release
      Release 3.3(2) Build 2
      Copyright _2004 Cisco Systems, Inc.

      The second way is to bring up a DOS prompt on the CiscoSecure ACS machine and run the following:

      C:\Program Files\CiscoSecure ACS v3.3\Utils>CSUtil.exe
      CSUtil v3.3(2.2), Copyright 1997-2004, Cisco Systems Inc
      Usage: [-q] [-b <backup filename> ] [-c] [-d] [-e <number>] [-g] [-i <file>]
       [[-p] -l <file>] [-n] [-r <all|users|config> <backup file> ] [-s] [-u] [-y]
      ! Rest of the output it removed as irrelevant for this question.
      C:\Program Files\CiscoSecure ACS v3.3\Utils>

      The second option is better.

    8. Can ACE server (SDI) and Cisco Secure ACS be installed on the same system?

      Answer: Yes there is no problem with running both Cisco Secure ACS and the ACE server (SDI) on the same machine.

    9. Do I need to have the SDI client installed?

      Answer: When using the SDI database as an external database, it is necessary to install SDI ACE client on the same machine on which Cisco Secure ACS is running. Also note that it is a good practice to install SDI before installing Cisco Secure ACS.

    10. Can we send accounting information to another system and also have a copy on the local system?

      Answer: Yes this is possible and it is configured under System configuration: Logging.

    11. Can CS ACS act as a proxy server to other servers?

      Answer: Yes, CS ACS can receive authentication requests from the network access servers (NASs) and forward them to other servers. You need to define the other servers by going to the Network Configuration > AAA Servers section on the source. The source server is defined as a TACACS+ or RADIUS NAS on the target. Once those are defined, configure the Distributed System Settings in the source Network Configuration to define the proxy parameters.

    12. What kind of web server and database does CS ACS use? Who provides patches for those two components?

      Answer: CS ACS has its own proprietary database, which spreads over to multiple files. The CS ACS web server is also Cisco proprietary. If any vulnerability is found, Cisco provides the patches because, unlike other software, those components are Cisco proprietary.

    13. How do I back up CS ACS?

      Answer: You can back up CS ACS through the GUI using the System Configuration tab, or you can use the command-line interface (CLI). If you use the GUI, there is a backup of the users, groups, and Registry settings. If you use the CLI, to back up users and group information, use $BASE\utils\csutil –d. To back up users, groups and Registry settings, use $BASE\utils\csutil -b.

    14. Can I use the backup utility on one CS ACS and then restore the information on another server?

      Answer: No, the backup utility is intended to save the user, group, and Registry information from one CS ACS box and restore it to the same CS ACS box running the same version of software. If there is a need to clone a CS ACS box, replication is available instead.

      If you need to copy only users and groups from one server to another, use the csutil -d command. The resulting dump text (.txt) file is then copied to the target box, and you can use the csutil -n -l command to initialize the database and import the users and groups.

    15. Is domain stripping supported with CS ACS?

      Answer: Yes, CS ACS does support domain stripping. This is useful when there is a combination of Virtual Private Dialup Network (VPDN) and non-VPDN users.

      Domain stripping is also useful when the external NT database is used for authentication. The first time the users log in, the username is populated automatically in CS ACS. Since a user may come in as "DOMAIN_X\user" or as "user," names may appear in the CS ACS as "DOMAIN_X\user" or as "user," resulting in both entries in the database. The duplicate entries can be avoided by using domain stripping, wherein the prefix domain with the delimiter "\" can be erased to have a consistent database. You can set this up by going to Network Configuration > Proxy Distribution Table.

    16. After successful installation of CS ACS, services are running. However, when I try to bring up the GUI, I get this error: "Invalid administration control." What should I do?

      Answer: If you have proxy server configured on the browser, you will see this message. To work around the problem, disable the proxy server completely.

    17. What is the limit of NASs that can be supported by CiscoSecure ACS for Windows?

      Answer: There is no limit. The number simply depends on the number that the Windows Registry can hold, as the NAS information goes to Windows Registry. It is estimated that the Windows Registry can hold thousands of NASs. Note that, unlike users or groups information, NAS information does not go the CS ACS database.

    18. Where does the CS ACS copy the configuration of the old CS ACS and how can that be useful if the upgrade fails?

      Answer: When upgrade is performed from one version to another. The previous CS ACS version configuration is copied to the following hidden folder:

      %systemroot%\Program Files\CiscoSecure ACS Configuration

      If you run into a problem with an upgrade, the system can be purged of all information, such as the Registry, folders and so on. If you leave the saved configuration folder, the next installation will find this information and will try to import the configuration from the old settings. This may come to your rescue when an upgrade fails due to file permission problems and so on. So, you must not remove this folder.

    19. How can I disable the users' option to change the password by using Telnet to access the router?

      Answer: You can change the password after using Telnet to access the router and click Enter without entering any password. This behavior can be prevented with the following setting on CS ACS.

      Step 1

      Back up the local Registry.

      Step 2

      Go to Registry key



      Step 3

      Add a Registry value by highlighting CSTacacs, right-clicking and selecting NEW-DWORD.

      Step 4

      When the new key appears on the right-hand side of the window, type disablechangepassword into the new key window.

      Step 5

      The default value for the new key is 0, which allows users to change the password. Right-click on the new key, select Modify, and then change the key value to 1 to disable the ability to change the password.

      Step 6

      After adding this new key, restart the CSTacacs and CSAuth services.

    20. When was PPTP (Point-to-Point Tunneling Protocol) with MPPE (Microsoft Point to Point Encryption) keying support introduced to Cisco Secure ACS for Windows?

      Answer: This was introduced on CS ACS version 2.6.

    21. How can I import a large number of NASs?

      Answer: The procedure to bulk import NASs is similar to the import of users. The following flat-file is an example:



      The NASs may also be imported into a particular Network Device Group. The following flat-file is an example:


    22. What databases are supported for the synchronization?

      Answer: CSV files and any ODBC-compliant database such as Oracle and MS SQL are supported.

    23. With Cisco Secure you can force users to change their passwords after a given time period. Can you do this when you are using the Windows NT database for authentication?

      Answer: This feature is available in all versions when you are using the Cisco Secure database for authentication. From version 3.0, support of Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) Version 2 and MS-CHAP Password Aging is available. This works with the Microsoft Dial-Up Networking client, the Cisco VPN Client (versions 3.0 and later), and any desktop client that supports MS-CHAP. This feature prompts you to change your password after a login attempt when the password has expired. The MS-CHAP-based password-aging feature supports users who authenticate with a Windows user database and is offered in addition to password aging supported by the Cisco Secure ACS user database. This feature has been added in CS ACS 3.0, but it also requires device/client support. Cisco Systems is gradually adding such device/client support to various hardware.

    24. How can users change their own passwords?

      Answer: Users can be notified of expiring Cisco Secure ACS database passwords on dial connections if the Cisco Secure Authentication Agent is on the PC. You can also use User Changeable Password (UCP) software, which runs with Microsoft IIS, once the users are in the network. When the users are on the network, they can point their browsers to the system where User Control Point (UCP) is installed and change their passwords.

    25. My CS ACS "Logged in Users" report works with some devices, but not with others. What is the problem?

      Answer: For the "Logged in Users" report to work (and this also applies to most other features involving sessions), packets should include at least the following fields:

      • Authentication Request packet
      • Accounting Start packet
      • Accounting Stop packet

      Attributes (such as nas-port and nas-ip-address) that appear in multiple packets should contain the same value in all packets.

      If a connection is so brief that there is little time between the start and stop packets (for example, HTTP through the PIX), then the report entitled "Logged-in Users" will not work either.

      CS ACS versions 3.0 and later allow the device to send either nas-port or nas- port-id.

    26. How are user passwords stored in CS ACS?

      Answer: Passwords are encrypted using the Crypto API Microsoft Base Cryptographic Provider v1.0. This offers either 56-bit or 128-bit encryption, depending on how the server is set up. The default cipher will be RC4.

    27. Can I change the default port for RADIUS and TACACS+ protocols on CS ACS?

      Answer: Yes, you can, but it is strongly discouraged. RADIUS Protocol listens on UDP/1645 and UDP/1812 for Authentication & Authorization and UDP/1646 and UDP/1813 for accounting. The location for ports for RADIUS is as follows:

      This can also be changed in the newer version:
      AccountingPort = 1646
      AccountingPortNew = 1813
      AuthenticationPort = 1645

      AuthenticationPortNew = 1812

      You can change any of the values previously listed. TACACS+ protocol on CS ACS listens by default on TCP/49. You can change the TACACS+ port by editing attribute values of the proper key in the Windows Registry:



      As mentioned before, it is strongly discouraged to change these default ports to something else.

    28. I am unable to delete the users and some users seem to belong to multiple groups. How may I get around the problem?

      Answer: Open up DOS prompt of CS ACS Server and type $BASE\utils\csutil -q -d -n -l dump.txt. Here "$BASE" is the directory where the software was installed. Issuing this command causes the database to be unloaded and reloaded to clear up the counters. Before performing this task, we strongly recommend that you back up the CS ACS database.

    29. I cannot start services for RADIUS after re-installing the software a few times. The event error says that service was terminated with "service specific error 11".

      Answer: Here are some possible reasons for encountering the problem:

      • The most common problems occur when you run Windows with an unsupported service pack or there is software contention with another application. Check installation guide and the release notes for the supported OS and service pack.
      • To check for port conflicts, go to the command line of the server and type netstat -an | findstr 1645 and netstat -an | findstr 1646 to see if any other service is using these User Data Protocol (UDP) ports. If another service is using these ports, you will see something similar to the following:
        UDP *:*

        UDP *:*

      • Microsoft Server services may not have been started. To check this, go to Control Panel > Services and ensure that the Server service options for Started and Automatic are selected.
    30. When accessing CS ACS GUI through a firewall, the address for the server in the URL field changes from a global IP address to a local address. Why does this happen?

      Answer: The global IP address does not change when you change to subsequent pages after the initial login from version CS ACS 3.0.

    31. Can a user be in more than one group at a time?

      Answer: No, a user cannot be in more than one group at a time.

    32. Are the dynamically mapped users stored in cache replicated?

      Answer: Yes. Dynamically mapped users are stored in cache in the same way as internal users. Those dynamic users simply never refer to the password fields and the group can be dynamic (mapped by the external authenticator). CS ACS replicates the group/user database with both internal and external users at the same time. You cannot do one type without the other, as replication simply performs remote file copies from master to slave.

7. Best Practices | Next Section Previous Section

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