Microsoft Forefront TMG logs size fields the wrong way around

If you’re using Microsoft Forefront Threat Management Gateway, there is a bug in the logging that causes Bytes Sent and Bytes Received to be logged in reverse. This seems to only affect the Web Proxy logs – both SQL and W3c . We noticed in a few web reports, that people were generally uploading a lot more than they were downloading. So we checked the logs and verified the buggy behavior:

Microsoft TMG Log showing Bytes Sent consistently larger than Bytes Received

Microsoft TMG Log showing Bytes Sent consistently larger than Bytes Received

This issue has been confirmed by the Microsoft Forefront TMG team, and unfortunately there is no ETA for a fix.

We obviously don’t want our reports showing incorrect usage figures, so we’ve fixed our TMG loader so that it imports the ‘bytesrecvd’ field into the Bytes Sent aggregate, and the ‘bytessent’ field into the Byte Received aggregate.

But what if Microsoft release a fix? What we’ve done is implemented a loader property to allow you to turn off this behavior. This will allow you to import your old logs with the fields reversed, and your new logs with the fields the right way around.

To access the loader property:

  • On the import wizard, select the Microsoft FTMG format and click the Properties button on the toolbar
  • Select Microsoft FTMG from the drop down list
  • Notice the option to ‘Reverse Bytes Sent and Received to compensate for bug in TMG’s logging’. Leave this checked until Microsoft issue a fix.

Microsoft TMG Option to Reverse Bytes Sent and Received

Microsoft Forefront TMG Loader Option to Reverse Bytes Sent and Received

This fix is available in Vantage build (and above) which has been released as an auto update. So simply select Tools | Check for updates to ensure you have this fix.


Co-founder and Chief Product Officer at (WebSpy's Parent Company)
I’m a co-founder, software product designer, web developer, and UX guy from Perth, Western Australia currently living in Bellevue, Washington USA.

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