Bupa (pronounced /buËpÉ/) is an international healthcare group, with its origins and headquarters in the United Kingdom but now serving 32 million customers in 190 countries. It is a not-for-profit private healthcare company, as opposed to the UK's National Health Service (NHS), which is a tax-funded healthcare system.
IPsec is an end-to-end security scheme operating in the Internet Layer of the Internet Protocol Suite, while some other Internet security systems in widespread use, such as Transport Layer Security (TLS) and Secure Shell (SSH), operate in the upper layers at the Transport Layer (TLS) and the Application layer (SSH).
In tunnel mode, an IPSec header (AH or ESP header) is inserted between the IP header and the upper layer protocol. Between AH and ESP, ESP is most commonly used in IPSec VPN Tunnel configuration.The packet diagram below illustrates IPSec Tunnel mode with ESP header : ESP is identified in the New IP header with an IP protocol ID of 50.The packet diagram below illustrates IPSec Tunnel mode with AH header :The AH can be applied alone or together with the ESP, when IPSec is in tunnel mode. AHâs job is to protect the entire packet.PSec transport mode is usually used when another tunneling protocol (like GRE) is used to first encapsulate the IP data packet, then IPSec is used to protect the GRE tunnel packets. IPSec protects the GRE tunnel traffic in transport mode.