The number of Internet connections still increases. More and more providers are not able to assign one public IPv4 address to every client because the IPv4 space has been consumed. In such cases, "Dual-Stack Lite" is a common solution. This protocol is specified in RFC6333 and it allows providers to share their limited IPv4 addresses with all the clients based on an IPv6 network. The presentation will explain the protocol "Dual-Stack Lite" from a security point of view. In the worst case, all IPv4 devices in a home network can be reached directly from the Internet. This could be demonstrated in the past! The presentation will give important information to all those providing services only with IPv4, "Dual-Stack Lite" providers and all respective users.