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Analysis of ISAPI filter-based transactions

The WhaTap .NET agent provides the ISAPI filtering feature to enable tracing transactions for various applications running on IIS. This allows for a wide range of monitoring, including requests based on technologies other than .NET, such as ASP, ASP.NET, CGI, and ISAPI extensions.

Caution

The ISAPI filter feature is supported starting from WhaTap .NET agent version 2.4.0 through 2.4.4 and later.

Installation​

  1. Install the .NET agent following the Agent installation instructions.

  2. After installing the agent, copy the whatap_isapi_filter.dll file to the root directory of the target site.

    C:..> copy "C:\Program Files\WhaTap .NET\whatap_isapi_filter.dll" C:\inetpub\yoursite

    • If you copy the filter file into the directory where the IIS website is running, no additional setup is required.

    • The filter file does not necessarily have to be located in the directory where the website is hosted, but the path and file must have read and execute roles granted to the IIS_IUSRS group.

Setting the ISAPI filter​

ISAPI filters can be applied server-wide or individually to sites.

Applying the server-wide filter​

To apply filters to requests from all websites hosted on IIS, set it as follows.

Apply server-wide filter

  1. Run the IIS Manager.

  2. In the tree on the left, select a server node.

  3. Double-click the ISAPI filter icon in the center area.

Applying individual site filters​

To filter transactions on individual sites, set as follows.

Apply individual site filters

  1. Run the IIS Manager.

  2. In the tree on the left, select a target site.

  3. Double-click the ISAPI filter icon in the center area.

Adding filter items​

Added a filter

  1. Click the Add button in the task pane on the right.

  2. Specify the filter name freely.

  3. Locate and select the whatap_isapi_filter.dll file.

  4. Click.

If the ISAPI filter does not work​

If it does not work after setting the filter, you may need to add ISAPI and CGI restrictions.

filter does not work sc

  1. In the tree on the left in IIS Manager, select a server.

  2. Double-click the ISAPI and CGI restriction icons in the center area.

  3. Click the Add button in the task pane on the right.

  4. Select the whatap_isapi_filter.dll file.

  5. Enter the item name.

  6. Check in the Allow extended path execution.

  7. Click.

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