Teredo is a method of tunneling IPv6 packets over IPv4 that is capable of providing direct connections even in situations where both ends are behind NAT gateways. The efficiency of virtual PeerToPeer networks greatly benefits from this capability.

However, it does require that

• there is no FireWall between you and the Teredo server
• you don't have a realworld IPv6 address from somewhere else
• you are not behind a symmetric NAT or cone NAT gateway. If so, you may be able to employ some other means such as setting up 6to4 on the NAT device in order to get an IPv6 address.

Implementation notes

Linux, FreeBSD:

You can use Miredo's client mode to implement Teredo on Linux or FreeBSD, provided your Kernel has IPv6 support.

Notes:

• Linux 2.4 and above use symmetric NAT -- if this causes problems, set up 6to4 on your Linux box instead.
• It will work on m0n0wall?, which uses cone NAT on a FreeBSD Kernel.

MicrosoftWindows:

You need XP Service Pack 2 or the Advanced Networking Pack. On a CommandLine, do

ipv6 setup
netsh interface ipv6 set teredo client

Note: if you are on a MicrosoftWindows domain you must substitute client for enterpriseclient.

Now you should be able to use VoIP and P2P applications that support IPv6 as if you had a realworld IP address.

You can monitor the interface using

netsh interface ipv6 show teredo

CategoryNetworking