The IP Helper (iphlpsvc) service offers IPv6 connectivity over an IPv4 network. IPv6 solves many IPv4 issues regarding address depletion, security, autoconfiguration, and extensibility. This service allows IPv6-enabled sites and hosts to communicate through IPv6 over an IPv4 infrastructure-for example, the Internet. This is often referred to as "6to4." IPv6 sites and hosts can use their 6to4 address prefix and the Internet to communicate. They do not need to obtain an IPv6 global address prefix from an Internet service provider (ISP) to connect to the IPv6-enabled portion of the Internet.
6to4 is a tunneling technique that is described in RFC 3056. The 6to4 hosts do not require any manual configuration, and they use a standard autoconfiguration to create 6to4 addresses. The 6to4 technique uses the global address prefix of 2002: WWXX:YYZZ::/48, where WWXX:YYZZ is the colon-hexadecimal representation of a public IPv4 address (w.x.y.z) that is assigned to a site or host, also known as the Next Level Aggregator (NLA) portion of a 6to4 address.
The IP Helper service also supports 6over4, also known as IPv4 multicast tunneling, a technique that is described in RFC 2529. The 6over4 technique allows IPv6 and IPv4 nodes to communicate through IPv6 over an IPv4 infrastructure. It uses the IPv4 infrastructure as a multicast-capable link. For 6over4 to work correctly, the IPv4 infrastructure must be IPv4 multicast-enabled.
If the IP Helper service stops, the computer only has IPv6 connectivity if it is connected to a native IPv6 network.
This service is installed by default and its startup type is Automatic. When the IP Helper service is started in its default configuration, it logs on by using the Local System account.
The IP Helper service is dependent upon the following system components:
- NetIO Legacy TDI Support Driver
- TCP/IP Protocol Driver
- Network Store Interface Service
- NSI proxy service driver
- Remote Procedure Call (RPC)
- DCOM Server Process Launcher
- RPC Endpoint Mapper
- Windows Management Instrumentation