Tunnel6 client is opensource software distributed under GNU/GPL3 licence which provides you connectivity over the IPv6 protocol.
Client uses your IPv4 connectivity to create tunnel between client and server over the UDP protocol with default port 6060.
It should also go through all NATs and classic firewalls..
It uses TUN device, which is standard Linux component for creating virtual interface and transfering data.
Tunnel6 server is opensource software distributed under GNU/GPL3 license which provides connectivity over the IPv6 protocol to IPv4 only clients.
Server needs IPv6 and IPv4 connectivity to create tunnel between client and server over the UDP protocol with default port 6060 on v4 side and also communicate with IPv6 world.
Server can provide any routed prefixes for each client too
Server puts selected network interface to promiscuous mode for listening IPv6 packets of connected clients and sends NDP neighbour solicitation.
You can download Tunnel6 at http://repo.or.cz/w/tunnel6.git