A digital envelope refers to the data obtained by the sender using the receiver's _____ to encrypt the symmetric key[fill in the blank]*
Heartbeat message (He11o message): The two FWs send heartbeat messages to each other periodically (the default period is ( ) seconds) to check whether the peer device is alive. (fill in the blank)
On the surface, threats such as viruses, loopholes, and Trojan horses are the causes of information security incidents, but at the root, information security incidents are also closely related to people and the information system itself.
Digital envelope technology means that the sender uses the receiver's public key to encrypt the data, and then sends the ciphertext to the receiver ( )[Multiple choice]*
Which of the following VPNs cannot be used in a Site to-Site scenario? ( )[Multiple choice]*
