Using the VPM, how do I block a download based on file size?
You want to:
1. Deny anyone downloading a file greater than a certain size.
2. Ensure proper functionality if the response header does not have a content-length header.
3. Use Visual Policy Manager (VPM) to control this.
To block download file size based on the "Content-Length" header, complete the following steps:
1. Open the VPM.
2. Create or open a Web Access Layer.
3. Create the following rule:
Destination: Set > New > Response Header; select Header Name: Content-Length, and put Header Regex: $. Name it as No_Content_Length, then right-click and select NEGATE.
Explanation of Rule1: ALLOW any sites that does not have a content-length header in its response header.
Rule2: (For explanation in picture, please go to KB4440)
Destination: Set > New > Response Header; select Header Name: Content-Length, and put in the desired Regex from the list below (for example: 50MB). Name it, then right-click and select NEGATE.
Explanation of Rule 2: DENY any file size that does not match Regex from the list (file size is larger than the regex number).
Examples of Regular Expression (Regex) syntax:
Currently, the only way that you can limit the size of HTTP objects returned is by creating policy that matches on the content-length header of the object returned. Objects that are not returned with a content-length will not match the following policy. Proxied FTP requests are not affected by this policy because they are not returned with a content-length header.
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