Here’s a clear, concise write-up suitable for a technical blog, FAQ, or internal IT knowledge base. The Teredo Tunneling Pseudo-Interface is a virtual network adapter in Microsoft Windows (starting with Vista and Server 2008) that enables IPv6 connectivity to devices still sitting behind IPv4 network address translators (NATs). It implements the Teredo tunneling protocol, often called IPv6 over UDP through NATs . How It Works Teredo encapsulates IPv6 packets inside IPv4 UDP datagrams. The pseudo‑interface handles this encapsulation and de‑encapsulation in software, allowing an IPv6‑capable host on a private IPv4 network to reach IPv6 resources on the public internet without native IPv6 support from the ISP or router.