How does ONTAP Native FPolicy determine a file extension

Question

• How does ONTAP Native FPolicy determine the file extension when a file name contains one or more periods (.)?
• For example, what extensions are used for FPolicy matching for the following file names?

Answer

• Native FPolicy performs file screening based on the file extension rather than the file contents.
• A period (.) is not included in the extension configured in the FPolicy extension list.

Example1:

• When a file name contains multiple periods, such as sample.tar.gz, Native FPolicy matches the portion after the last period as the extension.
• Therefore the extension of file sample.tar.gz is gz but not tar.gz.
• The . itself is not part of the extension configured for FPolicy matching.
• For files that do not have an extension, monitoring can be controlled by the following FPolicy scope option:

The following behavior was verified in testing:

• sample.txt -> txt
• sample.tar.gz-> gz
• sample 

This file name does not have a file extension.

FPolicy provides the following scope option to control whether objects without an extension are monitored:

• sample.

Testing from a Windows SMB client confirmed that Windows did not allow a file name ending with a period (.) to be created.

Therefore, Native FPolicy extension matching for sample. could not be evaluated through the tested Windows SMB client.

• sample.カタカナ漢字 and sample._→⇒㈵

カタカナ漢字 and _→⇒㈵ could be configured as an extension and that the corresponding file operation was successfully blocked by Native FPolicy.

Note: This confirms the behavior for the tested character only. It does not establish that every Unicode, multibyte, special, or environment-dependent character is supported as an FPolicy extension.