| 14.1 |  | The PIX Security Appliance Enables a Secure VPN |
| 14.1.3 |  | IPSec enables PIX Security Appliance VPN features |

| PIX Security Appliance versions 5.0 and higher use the industry-standard IP Security (IPSec) protocol suite to enable advanced VPN features. The PIX Security Appliance IPSec implementation is very similar to Cisco IOS IPSec that runs in Cisco routers.

IPSec is a Layer 3 mechanism for secure data transmission over IP networks. This ensures confidentiality, integrity, and authenticity of data communications over unprotected networks such as the Internet.

IPSec enables the following PIX Security Appliance VPN features:

- Data confidentiality - The IPSec sender can encrypt packets before transmitting them across a network.
- Data integrity - The IPSec receiver can authenticate IPSec peers and packets sent by the IPSec sender to ensure that the data has not been altered during transmission.
- Data origin authentication - The IPSec receiver can authenticate the source of the IPSec packets sent. This service is dependent upon the data integrity service.
- Anti-replay - The IPSec receiver can detect and reject replayed packets, which helps prevent spoofing and man-in-the-middle attacks.