Tunnelbroker

A tunnel broker is in the area of ​​computer networks, a service that provides the tunnel, which can be for example used to transport traffic backed up (Virtual Private Network) or encapsulated, eg To transport IPv6 over an IPv4 network.

Although there are several types of tunnel brokers so brokers are usually referred to, provide the tunnel, which allow IPv6 traffic to be routed over old IPv4 infrastructure (RFC 3053 ), but there can be IPv4 tunnel broker IPv4 Traffic lead on IPv6 infrastructure. The tunnel, pass the IPv6 over IPv4 use the method " Protocol 41 ", which is to bring the Protocol field of the IPv4 packet to 41 (hexadecimal 0x29 ) and pack the IPv6 packet in the packet. The other end point, a tunnel server unpacked the IPv6 packet and sends it then in the global IPv6 network.

Automatic configuration

Normally IPv6 tunnels are configured and built Setup Protocol or tunnel Information Control protocol over the tunnel. Very often, however, a manually configured tunnel.

Problems with Network Address Translation and routers

Protocol 41 tunnel, where IPv6 is packed directly in IPv4 are, may not stop working reliably in a position behind NATs - with many modern routers however there are no problems. You can work around problems by either puts the endpoint in a demilitarized zone, or click the NAT device; modern routers for home use that are IPv6 capable, it is now support. Also possible is the use of AYIYA or TSP ( Tunnel Setup Protocol), pack the IPv6 packets in UDP packets. This can happen easily, most firewalls (assuming there are no prohibitive rule).

A problem that may still occur is that a NAT rule is removed from the table, although the connection is not yet terminated. Here, the router can then nothing to do with any external incoming packets and discards them. Interrupting the tunnel connection to a packet, the user again transmits through the tunnel.

Many, especially older, (home) router routes generally no protocol 41 traffic.

Dynamic endpoints

If the client endpoint of the tunnel is a dynamic IP (as in retail broadband connections ), then the buyer must always inform the tunnel broker with a change of the new IP. This is done either manually via the website of the tunnel broker or through an automatic protocol such as TSP or heartbeat.

Other tunnel brokers allow a convenient web-based solution, in which a given URL is called, are included in the user name, password and host name or the ID of the tunnel. About the IP of the caller (the server for this solution is connected via IPv4 ), the end point will be updated.