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Miredo is an open-source Teredo IPv6 tunneling software, for the Linux, BSD and OS/X operating systems. It includes functional implementations of all components of the Teredo specification (client, relay and server). It is meant to provide IPv6 connectivity even from behind NAT devices.

There is more info, and software to download at the Miredo website.

Note that Miredo supports Teredo server, Teredo relay and Teredo client. From an ISP perspective, the Teredo client is not of interest since non-Windows clients generally get better results using 6to4 relaying.

Various ISPs will however announce a teredo prefix, to improve quality of users using teredo. Here is a list of ISPs currently announcing a teredo prefix.

Teredo server

A Teredo server needs two consecutive public IPv4 addresses, and global IPv6

Lets say the addresses are and, on network interface
eth0. Typically, you will already have configured as the "normal"
IP address on eth0. On Linux, you can add with iproute2:

As regards miredo-server, you simply have to put this single directive into

On the firewall side, miredo-server requires UDP port 3544 to be "open" on the
server, on both server's IPv4 addresses.

On the IPv6 side, no special setting should be needed. The server should
simply have a working IPv6 connectivity. It must be allowed to emit ICMPv6
packets with source in range 2001:0::/32 and destination within 2000::/3.

Teredo relay

The Teredo relay requires a single (public) IPv4 address and IPv6
connectivity. In miredo.conf, the "RelayType restricted" directive should
be sufficient (please comment out the ServerAddress directive if present). You
can optionaly select a port number (BindPort 12345) if a
fixed UDP port is needed, e.g. for firewalling purposes. IPv6 forwarding
should be enabled on the host:

Miredo will take care of adding required Teredo IPv6 routing and addressing on
the host. However because IPv6 forwarding is enabled on the host, IPv6
autoconfiguration will no longer work, so you will have to setup the
non-Teredo IPv6 addressing/routing manually.

An IPv6 route toward 2001:0::/32 should be exported to the other
IPv6 routers. Miredo does NOT take care of that; it can be done with the usual
mechanisms, either with manual routing configuration on the other routers, or
with a dynamic routing protocol (BGP, OSPFv3, IS-IS, RIPng...). In the latter
case a routing daemon will be needed in addition to Miredo (typically
Quagga/Zebra or BIRD).

N.B.: it is perfectly ok to run miredo and miredo-server on the same host.

Specific relay setup instructions: