Exam CAS-004 topic 1 question 497 discussion

The error messages you're seeing in the OpenVPN logs indicate that the client is encountering issues during the TLS handshake process, specifically during the initial client hello message. So, A TLS version mismatch between the client and server is a common cause of such errors. OpenVPN can support multiple versions of TLS (e.g., TLS 1.2, TLS 1.3), and if the client is trying to use a version that the server does not support (or vice versa), the handshake will fail, leading to errors like those shown in the log. So, the issue is most likely caused by a TLS version mismatch between the client and the server, where the client and server are trying to negotiate a protocol version that is incompatible.

While both a protocol mismatch and an attempt to establish an unencrypted connection can lead to TLS handshake failures, they manifest differently: Unencrypted Connection Attempt: - Scenario: The client tries to connect without initiating a TLS handshake. - Resulting Errors: The server expects TLS-encrypted data but receives plain, unencrypted data, leading to errors like unknown protocol. Protocol Version Mismatch (Option D): - Scenario: The client and server support different TLS versions (e.g., client uses TLS 1.2 while server expects TLS 1.3). - Resulting Errors: The server might produce errors indicating unsupported protocol versions or incompatible handshake messages, such as “Protocol version not supported” OR “SSL routines:tls_process_client_hello:wrong version number”

The TLS handshake errors indicate a TLS version mismatch between the VPN client and the OpenVPN server. Ensuring that both client and server configurations are aligned with compatible TLS versions and configurations is essential to resolving these errors and establishing a successful VPN connection.