Internet Protocol Security (IPSec) provides enhanced security features such as better encryption algorithms and more comprehensive authentication.

IPSec has two encryption modes: tunnel and transport. Tunnel encrypts the header and the payload of each packet while transport only encrypts the payload. Only systems that are IPSec compliant can take advantage of this protocol. Also, all devices must use a common key and the firewalls of each network must have very similar security policies set up. IPSec can encrypt data between various devices, such as:

1. Router to router
   
2. Firewall to router
3. PC to router
4. PC to serve

See also VPN’s