Management agents for directory servers support password change and set operations by default. For file-based, database, and extensible connectivity management agents, which do not support password change and set operations by default, you can create a .NET password extension dynamic-link library (DLL). The .NET password extension DLL is called whenever a password change or set call is invoked for any of these management agents. Password extension settings are configured for these management agents in Synchronization Service Manager. For more information about configuring password extensions, see the FIM Developer Reference.

Password synchronization works with the password change notification service (PCNS) on an Active Directory domain, and allows password changes that originate from Active Directory to be automatically propagated to other connected data sources. FIM accomplishes this by running as a Remote Procedure Call (RPC) server that listens for a password change notification from an Active Directory domain controller. When the password change request is received and authenticated, it is processed by FIM and propagated to the appropriate management agents.

	Important
	Bi-directional password synchronization is not supported by FIM. Configuring bi-directional password synchronization can create a loop, which will consume server resources and have a potentially negative effect on both Active Directory and FIM.

The PCNS runs on each Active Directory domain controller. The systems that receive the password notifications are known as targets. Your FIM must be configured as a PCNS target in Active Directory before password notifications are sent. The PCNS configuration must define an inclusion group and, optionally, an exclusion group. These groups are used to restrict the flow of sensitive passwords from the domain. For example, to send passwords for all users, but not send administrative passwords, you might choose to use Domain Users as the inclusion group, and Domain Admins as the exclusion group. For more information about configuring the password change notification service, see Using Password Synchronization.

The components involved in the password synchronization process are:

• Password change notification service (Pcnssvc.exe)–The password change notification service runs on a domain controller and is responsible for receiving password change notifications from the local password filter, queuing them for the target server running FIM, and using RPC to deliver the notifications. The service encrypts the password and ensures that the password remains secure until it is successfully delivered to the target server running FIM.
  
  
• Service principal name (SPN) – The SPN is a property on the account object in Active Directory that is used by the Kerberos protocol to mutually authenticate the PCNS and the target. The SPN ensures that the PCNS authenticates to the correct server running FIM, and that no other service can receive the password change notifications. The SPN is created and assigned by using the setspn.exe tool. For more information about configuring the SPN, see Using Password Synchronization.
  
  
• Password change notification filter (Pcnsflt.dll) – The password filter is used to obtain plaintext passwords from Active Directory. This filter is loaded by the Local Security Authority (LSA) on each Windows Server domain controller participating in password distribution to a target server running FIM. Once the filter has been installed and the domain controller has been restarted, the filter begins to receive password change notifications for password changes that originate on that domain controller. The password notification filter runs simultaneously with other filters that are running on the domain controller.
  
  
• Password change notification service configuration utility (Pcnscfg.exe) – The pcnscfg.exe utility is used to manage and maintain the password change notification service configuration parameters stored within Active Directory. These configuration parameters, such as defining the target servers, the password queue retry interval, and enabling or disabling a target server, are used when authenticating and sending password notifications to the target server running FIM.
  
  
• The service configuration is stored in Active Directory, so it is only necessary to update the configuration on one domain controller. Active Directory replicates the change to all other domain controllers.
  
  
• Remote Procedure Call (RPC) server on the server running FIM – When password synchronization is enabled, the RPC server on the server running FIM is started, enabling it to receive notifications from the password change notification service. RPC dynamically selects a range of ports to use. If you require FIM to communicate with the Active Directory forest through a firewall, you must open a range of ports.
  
  
• Password extension DLL – The password extension DLL provides a way to implement password set or change operations by means of a rules extension for any database, extensible connectivity, or file-based management agent. This is accomplished by creating an export-only, encrypted attribute named "export_password" that does not actually exist in the connected directory but can be accessed and set in provisioning rules extensions or can be used during export attribute flow. For more information about configuring password extensions, see the FIM Developer Reference.
  
  

Before you set up password synchronization for your FIM and Active Directory environment, verify the following:

• FIM is installed according to installation instructions.
  
  
• Management agents for the connected data sources to be managed for password synchronization are already created and the objects are being successfully joined and synchronized.
  
  

To set up password synchronization:

• Extend the Active Directory schema to add the classes and attributes necessary for installing and running the password change notification service (PCNS).
  
  
• Install the PCNS on each domain controller.
  
  
• Configure the service principal name (SPN) in Active Directory for the FIM service account.
  
  
• Configure the PCNS to communicate with the target FIM service.
  
  
• Configure the management agents for the connected data sources to be managed for password synchronization.
  
  
• Enable password synchronization on FIM.
  
  

For more information about setting up password synchronization, see Using Password Synchronization.

The process of synchronizing a password change request from an Active Directory domain controller to other connected data sources is shown in the following diagram:

1. The user initiates the password change request by pressing Ctrl+Alt+Del. The password change request, including the new password, is sent to the nearest domain controller.
   
   
2. The domain controller records the password change request and notifies the password change notification filter (Pcnsflt.dll).
   
   
3. The password change notification filter passes the request to the password change notification service (PCNS).
   
   
4. The PCNS verifies the password change request, then authenticates the service principal name (SPN) by using Kerberos, and forwards the password change request in encrypted RPC to the FIM target server.
   
   
5. FIM validates the source domain controller, then uses the domain name to locate the management agent that services that domain, and uses the user account information in the password change request to locate the corresponding object in the connector space.
   
   
6. By using the join table information, FIM determines the management agents that receive the password change, and pushes the password change out to them.
   
   

Password synchronization security

The following password synchronization security concerns have been addressed:

• Authentication from the password source – When the password change notification is received, Kerberos authentication is done by FIM as well as the source domain controller to ensure both the recipient and sender are valid. Upon receiving a password change notification, FIM ensures that the caller has an account in the Domain Controllers container of the domain it belongs to.
  
  
• Failed password synchronization to a target data source due to an insecure connection – If the management agent has been configured to require a secure connection but one is not detected, the synchronization fails. Synchronization still occurs if the management agent has been configured to allow non-secure connections. Allowing non-secure connections should be enabled only after examining and understanding the risks involved.
  
  
• Secure storage of passwords – FIM only stores encrypted passwords temporarily. All passwords received by FIM during a password change notification operation are encrypted as soon as they enter the FIM process. The moment they are successfully sent out to the target connected data source, they are decrypted, and the memory storing the password is immediately cleared. If the operation fails to write to the target connected data source, the encrypted password is stored until all retry attempts have been attempted, and then is cleared from memory.
  
  
• Secure password queues – Passwords stored in PCNS password queues are encrypted until they are delivered.
  
  

Password synchronization error recovery scenarios

Ideally, whenever a user changes a password, the change is synchronized with no errors. The following scenarios describe how FIM recovers from common synchronization errors:

• Failed password notification from Active Directory to FIM – This can occur if the network is down, or if the server running FIM is unavailable. The password change notification remains queued locally on the domain controller by the PCNS. The PCNS reattempts the notification according to its retry interval configuration.
  
  
• Failed password synchronization to a target data source – This can also occur if the network is down, or if the target data source is unavailable. The password change notification is queued and retried according to the management agent's configuration for retry attempt and retry interval. All passwords are encrypted while they are stored for retry, and deleted when the operation succeeds or the retry limits are hit.
  
  
• Activating a warm standby server running FIM after a failure – In the case of the primary server running FIM failing, you can configure a warm standby server for password synchronization, and activate it with no loss of password changes. For more information, see MIISactivate: Server Activation Tool.
  
  

Some failures are serious enough that no amount of retries is likely to result in a successful operation. In these cases, an error event is logged and the process is stopped. The following events are not retried:

Event	Severity	Description
6919	Information	A password synchronization set operation was not performed because the timestamp was out of date.
6921	Error	The password synchronization set operation was not processed because password management is not enabled on the target management agent.
6922	Error	The password synchronization set operation was not processed because password management is not configured on the target management agent.
6923	Warning	The password synchronization set operation was not processed because the target connector space object could not be found in the connected directory.
6927	Error	The password synchronization set operation failed because the password does not satisfy the password policy of the target system.
6928	Error	The password synchronization set operation failed because the password extension for the target management agent is not configured to support password set operations.

User-based password change management

FIM provides two web applications that use Windows Management Instrumentation (WMI) for resetting passwords. As with password synchronization, you activate password management when you configure the management agent in Management Agent Designer. For information about password management and WMI, see the FIM Developer Reference.

FIM creates two security groups during installation that specifically support password management operations:

• FIMSyncBrowse—Members of this group have permission to gather information about a user's accounts when doing search operations with WMI queries.
  
  
• FIMSyncPasswordSet—Members of this group have permission to perform account search, password set, and password change operations using the password management interfaces with WMI.
  
  

For more information about FIM security groups, see Using Security Groups.

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Password process