Which three statements are true about TACACS+？（）

• A、It is a Cisco proprietary protocol.
• B、It runs on TCP port 59. .
• C、Authentication and authorization are done at different stages.
• D、TACACS+ encrypts the entire body of the packet， but leaves a standard TACACS+ header.
• E、It is an industry standard protocol.
• F、TACACS+ encrypts both the entire body of the packet and the TACACS+ header.