What is IPSec

IPSec authenticates and encrypt each IP packets for securing IP communications. Followings are the benefits of IPSec:-

1.       Authentication

2.       Data Integrity

3.       Confidentiality

4.       Encryption

5.       Replay protection

As you can see below, Standard IP Packet encapsulates data with TCP Header and then with IP Header which is the least secured way of protecting data in transit.

 

But with IPSec, IPSec Header is included between TCP and IP Header. IPSec header consists of the following:-

·         Authentication Header (AH)

Provides authentication, data integrity and replay protection for an IP packet.

·         Encapsulating Security Payload (ESP) header

Provides authentication, data integrity, replay protection and data confidentiality for an IP packet.

 

IPSec can also be used in the Tunnel mode, by injecting IPSec Header between two different IP Headers, as shown below:-

source: http://www.learnmsexchange.com/windows-servers/518-what-is-ipsec