Wikipedia
In computing, Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts the packets of data to provide secure encrypted communication between two computers over an Internet Protocol network It is used in virtual private networks (VPNs) IPsec includes protocols for establishing mutual authentication between agents at the beginning of a session and negotiation of cryptographic keys to use during the session IPsec can protect data flows between a pair of hosts (host-to-host), between a pair of security gateways (network-to-network), or between a security gateway and a host (network-to-host) IPsec uses cryptographic security services to protect communications over Internet Protocol (IP) networks
IPSec - Wikipedia, the free encyclopedia