We are happy to announce the Azure IaaS VM backup support for network restricted storage accounts. With storage firewalls and Virtual Networks, you can allow traffic only from selected virtual networks and subnets. With this you can create a secure network boundary for your unmanaged disks in storage accounts.
You can also grant access for on-premises networks and other trusted internet traffic, by using network rules based on IP address ranges. With this announcement, we provide an ability for the user to perform and continue with scheduled and ad-hoc IaaS VM backups and restores for these VNET configured storage accounts.
Read about it in the Azure blog.