# VPN certificates and how they work

Certificates can be used for authenticating VPN gateways and the Forcepoint VPN Client.

In site-to-site VPNs, you can use both pre-shared keys and certificates as the authentication method. In mobile VPNs, certificates are always needed when the Forcepoint VPN Client is involved. However, if you use the hybrid authentication method with the Forcepoint VPN Client, only the gateway needs a certificate.

Certificates do not contain information that is specific to a particular VPN. You can use certificates for authentication in both the policy-based and route-based VPNs. A certificate authority (CA) issues certificates as proof of identity. Gateways that form a VPN tunnel are configured to trust the CA that signed the other gateway’s certificate. All certificates issued by a trusted CA are accepted as valid, so certificates can be added, renewed, and changed without affecting the VPN as long as the actual identity information is correct. The same certificate can be used for any number of VPNs with any number of gateways and VPN clients.

Certificates are always required for gateways to which the Forcepoint VPN Client connects. Certificates can optionally be used to identify VPN clients, but are not mandatory.

Certificates reduce the required maintenance work, because they do not have to be changed as frequently as pre-shared keys. All certificates are created with an expiration date, after which the certificate is no longer valid. Certificates signed by an Internal RSA CA for Gateways or an Internal ECDSA CA for Gateways are valid for three years from their creation. When a certificate expires, a new certificate is needed.