Which types of authentication can be used for IPsec Site to Site VPNs?

For IPsec Site-to-Site VPN configurations, the most commonly utilized types of authentication include digital certificates, RSA keys, and pre-shared keys (PSK). This suite of authentication methods is specifically designed for establishing secure connections between two networks over the internet.

Digital certificates serve to confirm the identity of the entities involved in the VPN communication, ensuring that both sides can validate each other's authenticity through a trusted Certificate Authority (CA). RSA keys, which are part of a public key infrastructure, provide a robust method of encryption and secure key exchange. Pre-shared keys are a simpler option, where a shared secret is used prior to establishing the VPN connection and are suitable for many smaller or less complex deployments.

Other authentication methods listed—such as username and password, two-factor authentication, and email verification—are typically not utilized in the context of IPsec Site-to-Site VPNs. Username and password authentication is more common in user-level VPNs rather than creating site-to-site connections. Two-factor authentication adds an extra layer of security, but its implementation is generally not standard for fully automated site-to-site connections. Similarly, email verification does not apply to the establishment of a VPN tunnel, as it is not set up to validate systems at a network or device