Which modes of IPsec are commonly used to secure communications?

The commonly used modes of IPsec that secure communications are tunnel mode and transport mode.

Tunnel mode encapsulates and encrypts the entire IP packet, adding a new IP header to the packet, which results in a new packet that can traverse the Internet securely. This mode is particularly effective for virtual private networks (VPNs) because it allows secure communication between two networks over an insecure medium, such as the internet. It protects not just the payload but also the original IP header, providing end-to-end security for the data being transmitted.

Transport mode, on the other hand, only encrypts the payload (the data part) of the IP packet while leaving the original header intact. This mode is often used for end-to-end communications between two hosts, where the focus is on securing the data rather than the headers. It is typically applied in scenarios where both endpoints are IPsec-aware.

In summary, both tunnel mode and transport mode serve important functions in securing communications over networks, which is why they are recognized as the standard modes used within IPsec.