VMware’s ThinApp 4.0 product has added a new feature to the previous versions of ThinStall called AppSync. Among other things, AppSync allows for administrators to build ThinApp packages that periodically check in to a web site to see if there is an update.
Using VMware’s ThinApp 4.0 AppSync feature with a Microsoft Web Server can require additional configuration to the web server as, by default, IIS 6.0 does not allow access to any file with an unknown extension.
How do you set IIS 6.0 to allow download of files such as EXE’s or DAT’s. By default, Microsoft’s IIS 6.0 will not serve out any unknown extensions. This includes EXE and DAT. Therefore, when a user requests such file, whether it be via ThinApp or directly, IIS will reply back with a 404 status code. A look in the IIS log file will show the sub-status code of 3 meaning the complete status code is 404.3. This means that the MIME restrictions prevented the request.
Basic instruction needed for configuring IIS to allow downloading of EXE and DAT files.
- Open IIS Manager.
- Browse to the IIS Site or subfolder where the ThinApp EXE and DAT files sit.
- Right click on that site or subfolder and select PROPERTIES.
- Select the HTTP HEADERS tab.
- Click on the MIME TYPES button.
- In the extension box, type ".exe".
- In the MIME TYPE box, type "application/octet-stream".
- Click OK.
- Repeat steps 1 – 8 to add the ".dat" extension.
- Click OK on all windows to close them and apply settings.
NOTE 1: The solution is the exact same as in IIS 5.0 and IIS 5.1, but since those IIS versions were not locked down by default, there was never any need to apply these configurations (since it works "As Is").
NOTE 2: Instead of adding two MIME types, you can also just add one wildcard MIME Type with the extension of ".*". This, however, is not as secure as just adding the extensions you need.
NOTE 3: If the IIS site points to a folder path outside of the INETPUB folder, you may need to ensure the appropriate INTERNET GUEST ACCOUNT has READ access to the folder and files within it.