NATläbipääsu

NATläbipääsu, a term originating from Estonian, translates to "NAT escape" or "NAT traversal" in English. It refers to a set of techniques used to enable direct communication between two devices that are both located behind separate Network Address Translation (NAT) devices. NAT is commonly used in home and small office networks to allow multiple devices to share a single public IP address. However, it complicates direct peer-to-peer connections, as devices behind NAT do not have publicly routable IP addresses.

NATläbipääsu techniques aim to overcome this barrier. Common methods include UDP hole punching, STUN (Session Traversal Utilities for NAT), TURN (Traversal Using Relays around NAT), and ICE (Interactive Connectivity Establishment). UDP hole punching, for instance, relies on the observation that NAT devices often create temporary mappings for outgoing UDP packets, allowing incoming packets on the same port to pass through. STUN helps clients discover their public IP address and the type of NAT they are behind, which is crucial for establishing connections. TURN acts as a relay server when direct peer-to-peer connections are not possible. ICE is a framework that combines these techniques to reliably establish peer-to-peer connectivity in the presence of NAT and firewalls. These methods are essential for applications like Voice over IP (VoIP), video conferencing, online gaming, and peer-to-peer file sharing, allowing them to function effectively across diverse network environments.