IPsec, or Internet Protocol Security, is a suite of protocols used to secure communications at the network layer. IPsec can be used in a number of different modes to provide security for both transport and tunnel-mode traffic. Transport mode secures communication between two hosts, while tunnel mode encrypts and encapsulates traffic between two networks.

IPsec uses a variety of cryptographic algorithms to provide data confidentiality, integrity, and authentication. Data confidentiality ensures that only the intended recipient can read the data. Data integrity verifies that the data has not been modified in transit. Authentication verifies that the sender is who they claim to be.

IPsec is an important tool for ensuring secure communications across untrusted networks such as the Internet. By using IPsec, organizations can protect their data from eavesdropping and tampering by malicious actors.