Sync certain extensions only

Hi guys how can I choose in owncloud which files to allow sync? For example I want to have an allow list of files so owncloud can only sync that. This is mainly a security feature to prevent ransomware attacks etc.
Is that possible directly on owncloud or do I need something else?
Thanks!
Teo

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Hi Michael thanks for the reply.
Only issue I see is that I need to set that at client side.
Any chance to do it on the server side so that it blocks unknown file extensions?
It would be better to block it at the server level.
Regards,
Teo