Configure Log File Properties

Applies To: Windows Server 2008

Configure log file properties

You can configure Network Policy Server (NPS) to perform RADIUS accounting for user authentication requests, Access-Accept messages, Access-Reject messages, accounting requests and responses, and periodic status updates. You can use this procedure to configure the log files where you want to store the accounting data.

To prevent the log files from filling the hard drive, it is strongly recommended that you keep them on a partition that is separate from the system partition. The following provides more information about configuring accounting for NPS.

  • To send the log file data for collection by another process, you can configure NPS to write to a named pipe. To use named pipes, set the log file folder to \\.\pipe or \\ComputerName\pipe. The named pipe server program creates a named pipe called \\.\pipe\iaslog.log to accept the data. In the Local file properties dialog box, in Create a new log file, select Never (unlimited file size) when you use named pipes.

  • The log file directory can be created by using system environment variables (instead of user variables), such as %systemdrive%, %systemroot%, and %windir%. For example, the following path, using the environment variable %windir%, locates the log file at the system directory in the subfolder \System32\Logs (that is, %windir%\System32\Logs\).

  • Switching log file formats does not cause a new log to be created. If you change log file formats, the file that is active at the time of the change will contain a mixture of the two formats (records at the start of the log will have the previous format, and records at the end of the log will have the new format).

  • If you are administering a server running NPS remotely, you cannot browse the directory structure. If you need to log accounting information to a remote server, specify the log file name by typing a Universal Naming Convention (UNC) name, such as \\MyLogServer\LogShare.

  • If RADIUS accounting fails due to a full hard disk drive or other causes, NPS stops processing connection requests, preventing users from accessing network resources.

  • NPS provides the ability to log to a Microsoft® SQL Server™ database in addition to, or instead of, logging to a local file.


If you do not supply a full path statement in Log File Directory, the default path is used. For example, if you type NPSLogFile in Log File Directory, the file is located at systemroot\System32\NPSLogFile.

Membership in the Domain Admins group is the minimum required to perform this procedure.

To configure log file properties using the Windows interface

  1. Open the Network Policy Server MMC snap-in.

  2. In the console tree, click Accounting.

  3. In the details pane, in Local File Logging, click Configure Local File Logging. The Local File Logging dialog box opens.

  4. On the Log File tab, in Directory, type the location where you want to store NPS log files. The default location is the systemroot\System32\LogFiles folder.

  5. In Format, click Database-compatible. Or, to keep your log files in IAS format, click IAS.

  6. To configure NPS to start new log files at specified intervals, click the interval that you want to use:

    • For heavy transaction volume and logging activity, click Daily.

    • For lesser transaction volumes and logging activity, click Weekly or Monthly.

    • To store all transactions in one log file, click Never (unlimited file size).

    • To limit the size of each log file, click When log file reaches this size, and then type a file size, after which a new log is created. The default size is 10 megabytes (MB).

  7. To configure NPS to automatically delete log files when the disk is full, click When disk is full delete older log files. If the oldest log file is the current log file, it is not deleted.