What is Internet Protocol security (IPsec)

Ipsec is the internet security protocol this protocol is used to the transfer the data more secure between the network IPSec is the most popular standard for securing data over a network. ip protocol is responsible to transfer the data from source to destination and provide end to end security of the data in private. IPSec (short for IP Security) is a set of security standards designed by the Internet Engineering Task Force (IETF) to provide end-to-end protection of private data. Implementing this standard allows your enterprise to transport data across an untrustworthy network such as the Internet while preventing hackers from corrupting, stealing, or spoofing your communication. As part of a continuing effort by Microsoft Corp. to move toward industry security standards, Windows Server makes IPSec easier to configure.

Ipsec securing packets it work with the Network Layer, IPSec provides end to end encryption services . as well as other access protections for secure networking. when we send data source to destination then encript the data then send For example, IPSec can provide for end-to-end security from client-to-server, server-to-server, and client-to-client configurations using IPSec transport mode. IPSec also delivers machine-level authentication and encryption for VPNs based on the Layer 2 Tunneling Protocol. if we configure ipsec then should be must configure both site otherwise user can't communicate with server.

IPSec is a service of protocols that provides powerful protection, authentication, and optional privacy and replay protection services. The IPSec protocols encompass packet format, key exchange, and transforms that are defined by IETF

The IPSec packets are comprised of the following types:

IP Protocol 50: This is the "Encapsulating Security Payload (ESP)" format. It defines privacy, authenticity, and integrity.

IP Protocol 51: This is the "Authentication Header (AH)" format. It defines authenticity and integrity, but not privacy.

IPSec Modes
IPSec operates in two modes, which are defined as follows:

Transport Mode: In this mode, AH and ESP protect the transport payload. Transport mode defines end to end communication between source and destination computers.

Tunnel Mode: IPSec is implemented in tunnel mode when the final destination of the packet differs from the security termination point. This mode is used when the security is provided by a device that did not originate the packets, such as in VPNs or router forwarding.

IPSec Encryption:
The ESP protocol provides for data privacy using encryption. it is encrypt the data between source to destination Under Windows Server, IPSec utilizes encryption based on either DES (Data Encryption Standard), which is 56 bits, or 3DES (Triple DES), which is 3x56 or 168 bits in strength. nowadays's mostly use 3DES because it is make very secure data.

The ESP and AH protocols is that they define an path framework for packet header formats and processing rules although leaving the transforms unspecified. although, the cryptographic algorithms can be updated as old algorithms become relatively weaker and less secure. This section introduces the practical steps to configure IPSec on Windows Server.


Source: http://www.informit.com/guides/content.aspx?g=security&seqNum=24