In the cases of restricted cone or port restricted cone NATs, the client must send out a packet to the endpoint before the NAT will allow packets from the endpoint through to the client.
Trong trường hợp Restricted Cone hay Port Restricted Cone, client phải gửi ra 1 gói tin cho điểm cuối trước khi NAT cho phép gói tin từ điểm cuối trở lại client.