IPv6 (also know as IPng ``IP next generation'') is the new version of the well known IP protocol (also know as IPv4). Like the other current *BSD systems, FreeBSD includes the KAME IPv6 reference implementation. So your FreeBSD system comes with all you will need to experiment with IPv6. This section focuses on getting IPv6 configured and running.
In the early 1990s, people became aware of the rapidly diminishing address space of IPv4. Given the expansion rate of the Internet there were two major concerns:
Running out of addresses. Today this is not so much of a concern anymore since private address spaces (10.0.0.0/8, 192.168.0.0/24, etc.) and Network Address Translation (NAT) are being employed.
Router table entries were getting too large. This is still a concern today.
IPv6 deals with these and many other issues:
128 bit address space. In other words theoretically there are 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses available. This means there are approximately 6.67 * 10^27 IPv6 addresses per square meter on our planet.
Routers will only store network aggregation addresses in their routing tables thus reducing the average space of a routing table to 8192 entries.
There are also lots of other useful features of IPv6 such as:
Address autoconfiguration (RFC2462)
Anycast addresses (``one-out-of many'')
Mandatory multicast addresses
IPsec (IP security)
Simplified header structure
IPv4-to-IPv6 transition mechanisms
For more information see:
There are different types of IPv6 addresses: Unicast, Anycast and Multicast.
Unicast addresses are the well known addresses. A packet sent to a unicast address arrives exactly at the interface belonging to the address.
Anycast addresses are syntactically indistinguishable from unicast addresses but they address a group of interfaces. The packet destined for an anycast address will arrive at the nearest (in router metric) interface. Anycast addresses may only be used by routers.
Multicast addresses identify a group of interfaces. A packet destined for a multicast address will arrive at all interfaces belonging to the multicast group.
Note: The IPv4 broadcast address (usually xxx.xxx.xxx.255) is expressed by multicast addresses in IPv6.
Reserved IPv6 addresses:
ipv6-address prefixlength(Bits) description Notes :: 128 Bits unspecified cf. 0.0.0.0 in IPv4 address ::1 128 Bits loopback address cf. 127.0.0.1 in IPv4 ::00:xx:xx:xx:xx 96 Bits embedded IPv4 The lower 32 bits are the address IPv4 address. Also called ``IPv4 compatible IPv6 address'' ::ff:xx:xx:xx:xx 96 Bits IPv4 mapped The lower 32 bits are the IPv6 address IPv4 address. For hosts which do not support IPv6 fe80:: - feb:: 10 Bits link-local cf. loopback address in IPv4 fec0:: - fef:: 10 Bits site-local ff:: 8 Bits multicast 001 (base 2) 3 Bits global unicast All global unicast addresses are assigned from this pool. The first 3 Bits are ``001''.
The canonical form is represented as: x:x:x:x:x:x:x:x, each ``x'' being a 16 Bit hex value. For example FEBC:A574:382B:23C1:AA49:4592:4EFE:9982
Often an address will have long substrings of all zeros therefore each such substring can be abbreviated by ``::''. For example fe80::1 corresponds to the canonical form fe80:0000:0000:0000:0000:0000:0000:0001
A third form is to write the last 32 Bit part in the well known (decimal) IPv4 style with dots ``.'' as separators. For example 2002::10.0.0.1 corresponds to the (hexadecimal) canonical representation 2002:0000:0000:0000:0000:0000:0a00:0001 which in turn is equivalent to writing 2002::a00:1
By now the reader should be able to understand the following:
rl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500 inet 10.0.0.10 netmask 0xffffff00 broadcast 10.0.0.255 inet6 fe80::200:21ff:fe03:8e1%rl0 prefixlen 64 scopeid 0x1 ether 00:00:21:03:08:e1 media: Ethernet autoselect (100baseTX ) status: active
fe80::200:21ff:fe03:8e1%rl0 is an auto configured link-local address. It includes the scrambled Ethernet MAC as part of the auto configuration.
For further information on the structure of IPv6 addresses see RFC2373.
Currently there are four ways to connect to other IPv6 hosts and networks:
Join the experimental 6bone
Getting an IPv6 network from your upstream provider. Talk to your Internet provider for instructions.
Tunnel via 6-to-4
Use the freenet6 port if you are on a dial-up connection.
Here we will talk on how to connect to the 6bone since it currently seems to be the most popular way.
First take a look at the 6bone site and find a 6bone connection nearest to you. Write to the responsible person and with a little bit of luck you will be given instructions on how to set up your connection. Usually this involves setting up a GRE (gif) tunnel.
Here is a typical example on setting up a gif(4) tunnel:
# ifconfig gif0 create # ifconfig gif0 gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280 # ifconfig gif0 tunnel MY_IPv4_ADDR HIS_IPv4_ADDR # ifconfig gif0 inet6 alias MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR
Replace the capitalized words by the information you received from the upstream 6bone node.
This establishes the tunnel. Check if the tunnel is working by ping6(8) 'ing ff02::1%gif0. You should receive two ping replies.
Note: In case you are intrigued by the address ff02:1%gif0, this is a multicast address. %gif0 states that the multicast address at network interface gif0 is to be used. Since we ping a multicast address the other endpoint of the tunnel should reply as well).
By now setting up a route to your 6bone uplink should be rather straightforward:
# route add -inet6 default -interface gif0 # ping6 -n MY_UPLINK
# traceroute6 www.jp.FreeBSD.org (3ffe:505:2008:1:2a0:24ff:fe57:e561) from 3ffe:8060:100::40:2, 30 hops max, 12 byte packets 1 atnet-meta6 14.147 ms 15.499 ms 24.319 ms 2 6bone-gw2-ATNET-NT.ipv6.tilab.com 103.408 ms 95.072 ms * 3 3ffe:1831:0:ffff::4 138.645 ms 134.437 ms 144.257 ms 4 3ffe:1810:0:6:290:27ff:fe79:7677 282.975 ms 278.666 ms 292.811 ms 5 3ffe:1800:0:ff00::4 400.131 ms 396.324 ms 394.769 ms 6 3ffe:1800:0:3:290:27ff:fe14:cdee 394.712 ms 397.19 ms 394.102 ms
This output will differ from machine to machine. By now you should be able to reach the IPv6 site www.kame.net and see the dancing tortoise - that is if you have a IPv6 enabled browser such as mozilla.
There are two new types of DNS records for IPv6:
Using AAAA records is straightforward. Assign your hostname to the new IPv6 address you just got by adding:
MYHOSTNAME AAAA MYIPv6ADDR
To your primary zone DNS file. In case you do not serve your own DNS zones ask your DNS provider. Current versions of bind (version 8.3 and 9) support AAAA records.
This, and other documents, can be downloaded from ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/.
For questions about FreeBSD, read the documentation before contacting <[email protected]>.
For questions about this documentation, e-mail <[email protected]>.