To ensure that the ERP system only accepts traffic from Cloud Identity-Aware Proxy, what should be done?

To ensure that the ERP system only accepts traffic from Cloud Identity-Aware Proxy (IAP), validating the JSON Web Token (JWT) assertion in HTTP requests is essential. Cloud IAP acts as a gatekeeper for applications hosted on Google Cloud, requiring that incoming requests are authenticated. When a user accesses the ERP system, IAP generates a JWT that encodes identification information about the user and their authentication status.

By validating this JWT on the server side, the ERP system can authenticate that the request originated from IAP and not from any external or unauthorized sources. The JWT contains claims that specify the user’s identity, the scopes of access, and the issuer of the token. Implementing JWT validation ensures that only requests that conform to the expected authentication and authorization requirements are accepted, thereby effectively protecting the ERP system against unauthorized access.

Utilizing Cloud Functions for request validation doesn't specifically address the requirement to ensure traffic originates from IAP. Enabling two-factor authentication improves user security but does not restrict access to the ERP system based on source. Routing traffic through public IPs could expose the application to unauthorized access if proper security measures, such as IAM or firewall rules, are not enforced. Thus, validating the JWT assertion is the most direct and effective method to ensure