The Teredo IPv6 tunneling protocol encapsulates IPv6 packets into UDP/IPv4 datagrams, to allow hosts behind NAT devices to access the IPv6 Internet.

Miredo-server provides a Teredo server. Teredo servers help Teredo clients determine their NAT configuration, maintain their NAT binding, and perform hole punching when transmitting IPv6 packets to other Teredo clients and/or Teredo relays.