net-tools

The net-tools package includes tools like ifconfig and route, which will help us to configure IPv6 on an interface. First of all, we have to check if the net-tools package we have installed support IPv6. We have to look the output of ifconfig -? or route -? and look for something like inet6 or IPv6:

/sbin/ifconfig -? 2>& 1|grep -qw 'inet6' && echo "utility 'ifconfig' is IPv6-ready"

If we don't see the message utility 'ifconfig' is IPv6-ready the net-tools package doesn't support IPv6. We need to upgrade to a more recent version.

We can see the IPv6 address of our network interfaces:

ifconfig -a
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3247 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3247 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1451140 (1.3 MiB)  TX bytes:1451140 (1.3 MiB)

eth0      Link encap:Ethernet  HWaddr 00:05:1C:06:1D:6A
          inet addr:192.168.13.5  Bcast:192.168.13.255  Mask:255.255.255.0
          inet6 addr: fe80::205:1cff:fe06:1d6a/10 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:687058 errors:0 dropped:0 overruns:0 frame:0
          TX packets:762545 errors:0 dropped:0 overruns:0 carrier:0
          collisions:2804 txqueuelen:100
          RX bytes:77998834 (74.3 MiB)  TX bytes:131804041 (125.6 MiB)
          Interrupt:11 Base address:0x6c00

sit0      Link encap:IPv6-in-IPv4
          NOARP  MTU:1480  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

This is first time we use IPv6 and we can see the link local address of our network interface (eth0). These are special addresses and if we use this address as destination the packet would never pass through a router. These addresses are used to communications like:

• anyone else here on this link
• looking for special addresses, like routers

These addresses begin with:

fe8x
fe9x
feax
febx

but actually only the first range is in use (fe8x).

The host part of the address is computed by converting the MAC address of an interface (if available), with the http://standards.ieee.org/regauth/oui/tutorials/EUI64.htmlEUI-64 method, to a unique IPv6 address. If no MAC address is available for this device (virtual devices), something else (the IPv4 address or the MAC address of a physical interface) is used instead. So in our example:

fe80::205:1cff:fe06:1d6a/10

the value:

205:1cff:fe06:1d6a

is the host part and computed from the NIC's MAC address:

00:05:1C:06:1D:6A

Now we only have this IPv6 address in this network interface. When we setup our tunnel with Freenet6, we will have a global address provided by the Freenet6 server (in our case it will be a 6bone test addresses. It will begin with 3ffe prefix).