What Is IPsec?

Date First Published: 5th March 2022

Topic: Computer Networking

Subtopic: Internet Protocols

Article Type: Computer Terms & Definitions

Difficulty Level: 8/10

Learn more about what IPsec is in this article.

Short for internet protocol security, IPsec is a network protocol suite used for enabling encrypted and secure communications between devices. IPsec is commonly used in VPNs to secure data sent over private networks. It was developed by the IETF in the mid-1990s and it works by encrypting and authenticating the data packets. It is necessary for the sending and receiving ends of a packet to share a public key when using IPsec.

Note:

IPsec is a combination of the words 'IP', short for internet protocol and 'sec', short for security. IPsec is secure because of the added encryption.

VPNs

In terms of VPNs, IPsec is often used in the implementation of it. The encryption modes 'transport' and 'tunnel' are supported by IPsec. 'Transport' encrypts only the data of the packet, not the header, whereas 'tunnel' encrypts both the data and the header.

Steps of IPsec

The steps that IPsec uses are:

1. The keys are exchanged - A key is a random string of characters that is used for encrypting and decrypting data. Each device can encrypt the data from the other device using a key exchange.
2. Data is broken down into packets - All data transferred over a network is divided into smaller segments, known as packets. Packets contain a payload (the data being transmitted) as well as headers (the information about that data), in order for computers receiving the packets to know what to do with them. A range of headers is added by IPsec, including authentication and encryption information.
3. Each packet is authenticated - Authentication is provided by IPsec in order to ensure that the data packets are from a trusted source and not an attacker.
4. Each packet is encrypted - The data as well as the information about that data inside each data packet is encrypted by IPsec.
5. Each packet is transferred to its final destination - Through the use of a transport protocol, encrypted IPsec packets travel across one or more networks to their final destination.
6. Each packet is decrypted - The packets are decrypted at the other end of the communication, and the data can now be used.