TCP proxy for non-IPv6 applications

 6tunnel allows you to use services provided by IPv6 hosts
 with IPv4-only applications and vice versa. It can bind to
 any of your IPv4 or IPv6 addresses and forward all data to
 IPv4 or IPv6 host.
 .
 Tunnelling for application that don't speak IPv6. It can be
 used for example as an IPv6-capable IRC proxy in other network.