IPSEC VPN technology does not support NAT traversal when encapsulated with ESP security protocol, because ESP encrypts the header of the message

_____ can view the direction of the traffic in the firewall.

Information security graded protection is the basic system of national information security assurance work.

When an enterprise establishes its own information system, it checks every operation in accordance with the authoritative standards established internationally, and can check whether its own information system is safe or not.

Security policy conditions can be divided into multiple fields, such as source address, destination address, source port, destination port, etc. These fields have an "and" relationship, that is, only the information in the message and all fields If they all match, it is considered to have hit this strategy.