GRE Tunnels
GRE (Generic Routing Encapsulation) Tunnels are a tunneling protocol used to encapsulate a wide variety of network layer protocols inside virtual point-to-point links over an IP network. They create a secure, logical connection between two endpoints, allowing data packets to be transmitted as if they are traveling over a direct physical link, even across public or untrusted networks. This is commonly used for connecting disparate networks, such as in VPNs, multicast routing, or network virtualization.
Developers should learn GRE Tunnels when working on network engineering, cloud infrastructure, or systems administration tasks that require secure, scalable connectivity between remote sites or data centers. They are particularly useful for creating site-to-site VPNs, enabling multicast traffic over unicast networks, and supporting legacy protocols that aren't natively supported by modern IP infrastructures. For example, in cloud environments like AWS or Azure, GRE Tunnels can bridge on-premises networks with virtual private clouds.