How to get list of users who can access a file that I created and shared

The concern is that as a company, we would like to monitor whether our internal files have been mistakenly shared with unauthorised persons.

With NextCloud, we are able to see the list of user that we have shared the file to. However, if those people re-shared the file, we don’t have a clue.

Does anyone have an idea how we can monitor file sharing?

Many thanks.

Interesting question. You could tag these files:

and then use file access control to limit access (to certain groups, IPs, …):

Of a share you can see, who you shared the file with and it should also show when it was reshared (in NC 12 and higher):

Uncheck Allow resharing to disable users to re-share files shared with them.