| Term | Description |
| IPSec | IPSec (short for IP Security) is a group of related protocols for negotiating encryption and authentication at the IP (host-to-host) level. IPSec is a security extension of IPv4 and a requirement for IPv6 that encrypts all transmissions over a TCP/IP network. The IPSec protocols are defined in the new RFC 2401-2411 and 2451 (the original IPSec RFCs 1825-1829 are now obsolete). IPSsec tunnels use port 500/udp for Internet Key Exchange (IKE), as well as port 50 for Encapsulation Header (ESP), and/or port 51 for Authentication Header (AH). |