A protocol that underlies other Internet packet protocols such as UDP (User Datagram Protocol) and TCP/IP (Transmission Control Protocol/Internet Protocol) to provide encryption.
Sometimes the encryption/decryption is done by LAN (Local Area Network) card hardware. Some of the encryption algorithms used include
HMAC-SHA1 extended checksums for integrity protection, and TripleDES-CBC and AES-CBC for confidentiality. It is
quite complicated to use. VPNs (Virtual Private Networks)
are a simpler way to get much the same effect.