Disclaimer: This information is posted as-is and the content should be referenced at your own risk
This is an overview of how Sophos Web Interception works, with a specific focus on speed testing performance and the potential areas where issues may occur.
Sophos Web Protection / Web Control only applies to the following Browsers (as of Jan 14, 2020):
Note: Other browsers are not intercepted. Should you wish to control these, Application Control would be the best solution.
This overview applies to Windows, Windows Server, and MacOS systems, as they all operate with the same workflow - just with different interception mechanisms (see step #3).
When a browser is used, the following workflow applies. Caveats for each step will be provided at the bottom:
Internet speed tests can often report different than expected values due to how Sophos Web Interception works.
Speed tests use scripting to time the download of files. This download is around the entire workflow. They then divide the file sizes by the time to get the “speed”. Often, speed tests use several files of differing sizes to test, to allow for testing of faster connections.
In order to reduce the possible overhead, it is recommended on Windows to use a command line check, such as what can be found at https://www.speedtest.net/apps/cli.
The time to perform the SXL lookup and scanning of the downloaded file, add to file overhead - which result in speed values that may be lower than expected. SXL overhead remains the same no matter what the size of file, where scanning will take longer on larger files.
Note: It is recommended that when testing, no other web interception software is running (such as a VPN, or DLP software) to ensure it is only the Sophos Web Protection that is being checked.
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