##Compile Download the sourcefile tb_userspace.c and compile it by gcc
gcc tb_userspace.c -l pthread -o tb_userspace
Binary(Recommended) I compiled the source file on Debian 5.0 kernel 2.6.32-trunk-686 with gcc version 4.4.3 20100108, and the binary file can work well on kernel 2.6.18-128.2.1.el5.028stab064.7 You can download the binary file tb_userspace directly.
##Config and Example
You should first know what is 6to4 tunnel(or tunnelbroker or ISATAP).
6to4 encapsulates IPv6 package in IPv4 package. To use 6to4, A relay server and a public IPv4 address for the client is necessary. By default IPv4 address 192.88.99.1 is assigned for relay server and anycasted by ISP. Thus the default IPv6 addressfor the client must be 2002:IPv4_addr::IPv4_addr. e.g. 2002:0B0B:0B0B::0B0B:0B0B for client IPv4 address 11.11.11.11.
Some ISPs(like Hurricane Electric) provides tunnelbroker service. You can get your IPv6 address and IPv4 address of the relay server from the tunnelbroker provider or use the default one.
Other ISPs provide public ISATAP tunnel. ISATAP is another tunnel protocol a little bit different from 6to4 or tunnelbroker. The relay server announced its prefix and the client automatically uses IPv6 address as Prefix:0:5efe:xx.xx.xx.xx where xx.xx.xx.xx is the IPv4 address of the client. Currently TB-TUN cannot recognize the router announcement so you should configure your IPv6 address manually.
##Requisite
The host system must support TUN/TAP device.
If you have a firewall, you should allow IP proto 41(IPPROTO_IPV6) passing through.
Useage: tb_userspace tun_name remote_ipv4 local_ipv4 mode
The example below shows how to config a general 6to4 tunnel with client IPv4 address 11.11.11.11
setsid ./tb_userspace tun6to4 any any sit > /dev/null
ifconfig tun6to4 up
ifconfig tun6to4 inet6 add 2002:0B0B:0B0B::0B0B:0B0B/64
ifconfig tun6to4 mtu 1480
route -A inet6 add ::/0 dev tun6to4
(Or ip -6 route add default dev tun6to4, Thx the comments below)
tb_userspace takes exactly 4 arguments:
The 1st is the name of device TUN(here is 'tun6to4').
The 2nd is the IPv4 addr of relay server. If any is here, a 6to4 tunnel will be build.
The 3rd is the local IPv4 addr. If any is here, TB-TUN will not bind the local IPv4 address.
The 4th is the tunnel mode. Currently sit for 6to4 and tunnelbroker and isatap for ISATAP are available.
Note that if Remote_IPv4 address is specified, TB-TUN will only accept packages from this specified IPv4 address. So ./tb_userspace tb 192.88.99.1 any sit is not a proper way to set up 6to4 tunnel for it drops package from other IPv4 address, and only send packages to default gateway 192.88.99.1. It would cause problems when transmitting packages between 6to4 networks. (See Issue3)
Usually the MTU of most networks is 1500. So the MTU of IPv6 tunnel should be 1480 by removing the 20 bytes IPv4 header. To set a proper MTU that neither cause IPv6 packet be truncated nor be too small for IPv6, You'd better find the IPv4 MTU from you to your tunnel relay server by your self and set the IPv6 MTU by minus 20 bytes.
The example below shows how to config a tunnelbroker client with client IPv4 address 1.2.3.4, relay server 5.6.7.8 and client IPv6 address 2001:a:b:c::2/64
setsid ./tb_userspace tb 5.6.7.8 1.2.3.4 sit > /dev/null
ifconfig tb up
ifconfig tb inet6 add 2001:a:b:c::2/64
ifconfig tb mtu 1480
route -A inet6 add ::/0 dev tb
The example below shows how to config a ISATAP client whith client IPv4 address 1.2.3.4, relay server 5.6.7.8, and IPv6 prefix 2001:a:b:c::/64.
setsid ./tb_userspace isatap 5.6.7.8 1.2.3.4 isatap > /dev/null
ifconfig isatap up
ifconfig isatap inet6 add 2001:a:b:c:0:5efe:1.2.3.4/64
ifconfig isatap mtu 1480
route -A inet6 add ::/0 dev isatap
And now you can try to ping some IPv6-only hosts:
ping6 ipv6.google.com
PING ipv6.google.com(vx-in-x67.1e100.net) 56 data bytes
64 bytes from vx-in-x67.1e100.net: icmp_seq=1 ttl=55 time=43.0 ms
...