The security problem emerged because 25 years ago, the Internet didn’t have a huge impact and important on our life and on our private relations and information. Today, it definitely became public. As the Internet, has developed, the need of safety and protection has risen. A number of methods have derived. The technology brought secure communication to the IP is called IP Security short of IPsec.

IP is not an individual protocol, but a group of services and protocols that gives a total security solution for an IP network. Some of the different roles offered by IPsec include the following:

·      Privacy of data users.

·      Authentication of an information to assure that is not changed on the way of sending it.

·      Safety against the different types of attacks and hacks.

To encourage these activities and make them happened, a number of components was created that make up the genera package of security and the two important pieces are called the core protocols of IPsec which their role is to ensure the protection of different data and encoding it.

IPsec Authentication Header (AH): This protocol provides the verification services for IPsec. It grants the recipient to make sure that common devices haven’t change on their way to the receiver and the data is untouchable. It also provides security against so0called (replay attacks), or a message that is catches by an unauthorized user. This Protection is IP AH header that is fragmented.

Encapsulating Security Payload (ESP): This type of header ensures the integrity of the data in datagram. When the information is shown in a datagram and visual for us, it can be further secured using this protocol (ESP), which decodes the payload of the IP datagram. Both of these protocols provide security by adding a header that gather a lot of data. IPsec in this situation can complete two specific mode of operation, transport mode and tunnel mode. They are the closest mode related to the two-protocol cited above: authentication header (AH) and the encapsulating security payload (ESP), these two protocols give security, protection on the data.

Mode of Transport referring to its name, it’s a mode where the protocol protects the message sent down to IP from the transport layer. The message is done by AH and ESP header. Also, there is another the way that works too. When IPsec is used in transport mode, the header is adjusted only over this IP payload not in the IP header. The previous core protocols that we talked about AH and ESP headers appear between the original, single IP and the IP payload.

Moving on to the Tunnel mode, in this mode, IPsec is used to secure a completely encapsulated IP data after the IP header had already been applied to it. It appears in front of the original IP header and then the new IP header is added of the IPsec header. Overall, the entire original IP data is protected and then encapsulated within another IP data.