The customer needs a method to transmit logs securely using UDP or TCP over SSL. To follow best practices, a heavy forwarder would be most effective as it has the capability to handle SSL encryption and parse data efficiently. Opening a TCP port with SSL on a heavy forwarder ensures that the logs are securely transmitted and properly parsed before being sent to the indexing tier. Using a heavy forwarder in this context is more secure and efficient compared to other methods that may not handle SSL or parsing as effectively.