IPSec package security load (IPsec ESP) is a major protocol in the IPSec architecture that is mainly designed to provide a hybrid app for secure services in IPv4 and IPv6. IPSec ESP provides confidentiality and integrity by encrypting data that needs to be protected and places these encrypted data in the data part of IPSec ESP. Depending on user security requirements, this mechanism can be used to encrypt a segment of a transport layer (eg TCP, UDP, ICMP, IGMP), or to encrypt a whole IP datagram. The encapsulation is very necessary, so that confidentiality can be provided for the entire raw datagram.
The ESP header can be placed after the IP header, before the upper layer protocol head (transfer layer), or before the packaged IP header (tunnel mode). IANA is assigned to an ESP a protocol value 50, and the protocol header before the ESP header is always included in the "NEXT" field (IPv6) or "Protocol" field containing this value 50.
For more information, please visit the following page: 中文 版: http://www.networkDictionary.com/chinese/Protocols/esp.php
English: http://www.networkDictionary.com/Protocols/esp.php
