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To block file sharing through OneDrive, you need to:
Enable Webhooks and/or polling for files when setting up the CASB Adapter
(To read more: /wiki/spaces/SKYP/pages/2644672992)Set Enable Webhook for Files in the portal page Cloud Service Integration to Yes.
File Sharing inspection is based on Ethical Wall Conference Policies. To enable blocking file sharing set a conference policy to block file share.
Office 365 Groups
7.11.22 - From our new SharePoint version, we are supporting Governance inspection of Office 365 groups. Before that, we support only security groups and mail-security groups.
The meaning of this support is:
On regular SharePoint sites, you can’t share a file with an Office 365 group or set permission to the site to an Office 365 group if this group isn’t in the allowed groups.
On OneDrive, you cannot share files at all with Office 365 groups (in the previous version you cannot share files with security groups and mail-security groups)
Limitations:
It seems that is impossible to add an Office 365 group as a nested group of a security group
When sharing an Office 365 group on SharePoint/OneDrive, the name of the group will include “ Members” at the end. It’s important because the governance check allowed groups by the groups' names, so it’s not recommended to add Office 365 groups to allowed groups at all.
Webhook and short polling use a delta link to fetch the new members on the site. It seems that if you share a membership with an Office 365 group more than once, it’s not received in the delta link anymore.
So, it’s important to enable long-run polling also to handle those cases