I would like to create a L2L VPN between two organizations. Due to the hyphotesis that WannaCry was propagated in great part using these kind of connections, I would like to implement security measures to protect one end from the other.
What security requirements should be implemented?
Edit: From NIST "Guide to IPsec VPNs" a gateway-to-gateway or L2L VPN "is done tipically by deploying a VPN gateway onto each network and establishing a VPN connection between the two gateways. Traffic between the two networks that needs to be secured passes within the established VPN connection between the two VPN gateways. The VPN gateway may be a dedicated device that only performs VPN functions, or it may be part of another network device, such as a firewall or router."