A ProxySG has its Explicit HTTP proxy service set to Intercept. What is the first response code the client receives when connecting for the first time?

When a ProxySG is configured with its Explicit HTTP proxy service set to Intercept, it signifies that the proxy is set to intercept traffic aimed at an HTTP service. In this scenario, the first response code the client receives when attempting to connect is 407.

The 407 response code indicates that authentication is required for the client to access the requested resource through the proxy. Essentially, the proxy requests that the client authenticate itself and provide valid credentials. This is particularly important in environments where security is paramount, as the proxy needs to ensure that only authorized users can use the service.

This behavior is part of the proxy's mechanism to enforce security policies. If the user's credentials are not provided or are incorrect, the proxy will continue to respond with 407 status codes, prompting the client to supply valid authentication until access is granted.

The other response codes do not apply to this context. A 200 response code signifies success and would not be the first code sent in this situation. A 401 response generally indicates that authentication is required for the requested resource but is not specific to proxies, and a 403 response indicates that access to the resource is forbidden, which isn’t the initial response for an authentication challenge in this interception context. Hence, the 407