Edit File: ipv6-6to4.howto
v1.5 1st Sep 2003, Pekka Savola <pekkas@netcore.fi> HOW TO SET UP IPV6 WITH 6TO4 ---------------------------- 6TO4 IN SHORT ------------- 6to4 is a method of creating automatic IPv6 tunnels. You can connect to IPv6 Internet very easily without a need for a manually configured tunnel. For every globally unique IPv4 address, there exists a mapping for a subnettable /48 network (2^16 for subnetting, 2^64 bits for hosts). Return route can sometimes be non-optimal, leading to higher round-trip times. See below for references and more information. ASSUMPTIONS ----------- 1. You're running Red Hat Linux 7.1 or later. This is required for correct IPv6 by default settings, and IPv6 being enabled as a kernel module by default. 2. Your initscripts >= 6.02, for 6to4 support. 3. You have a static, globally unique IPv4 address. This is not an absolute requirement, but the only scenario discussed here. 4. Protocol 41 (IPv6-in-IPv4) is not being filtered in any IPv4 firewall. 5. 'iproute' package is installed. This is used by default for a lot more powerful tunneling capabilities. Note: even though 6to4 was supported with earlier releases of Red Hat Linux, below it is assumed that the initscripts package version this document comes with is used. INFORMATION NEEDED ------------------ Nothing :-). If you want to select a specific relay (rather than automatically selecting the closest one), you can define it with IPV6TO4_RELAY using the list below: http://www.kfu.com/~nsayer/6to4/ SETTING UP THE 6TO4 CONFIGURATION --------------------------------- Now, set up the configuration as follows: 1. Enable IPv6 and set 6to4 pseudo-interface as default gateway in /etc/sysconfig/network: echo "IPV6_DEFAULTDEV=tun6to4">> /etc/sysconfig/network 2. Edit your outbound (Internet) interface configuration. This can be e.g. ippp0, ppp0, eth0, or the like. Here, eth1 is used. /etc/sysconfig/network-scripts/ifcfg-eth0: --- DEVICE=eth0 BOOTPROTO=static ONBOOT=yes IPADDR=xx.yy.zz.ww [Globally unique IPv4 address] NETMASK=aa.bb.cc.dd [IPv4 settings up to this point] IPV6INIT=yes IPV6TO4INIT=yes --- Note: [i]ppp - interfaces need to be called in /etc/ppp/ip-up|down.local; if you are not using local files by yourself, this can easily be done with: cd /etc/ppp ln -s ip-up.ipv6to4 ip-up.local ln -s ip-down.ipv6to4 ip-down.local USING 6TO4 ---------- 6to4 automatic tunneling is brought up when the interface is brought up. You will see your 6to4 address prefix in device tun6to4 when done: inet6 addr: 2002:c15e:a001::1/16 Scope:Global Note that 'c15e:a001' is the hexadecimal representation of dotted-quad IPv4 address (IPADDR= above), here '193.94.160.1'. NOTE: iproute tools give more reliable data, try e.g. '/sbin/ip addr ls'. PROVIDING IPV6 TO YOUR LAN -------------------------- If you want to provide IPv6 for your LAN (e.g. connected on eth1) using your Linux system as a router, this can be done rather easily with 6to4. You will need to enable IPv6 forwarding (IPV6FORWARDING=yes in /etc/sysconfig/network) and install a router advertisement daemon. One such, 'radvd' is available in the distribution. You must configure the prefix your IPv4 maps to (see tun6to4 above) in /etc/radvd.conf or use certain automatic hooks. This is not covered here in detail; see radvd.conf(5) and /etc/sysconfig/network-scripts/ifup-ipv6 for details. Usually the following is enough: 1. Make sure that radvd package is installed. 2. Configure radvd as outlined in radvd.conf(5); the file could be something like: interface eth1 { AdvSendAdvert on; MinRtrAdvInterval 3; MaxRtrAdvInterval 10; prefix 0:0:0:1::/64 { Base6to4Interface eth0; AdvPreferredLifetime 120; AdvValidLifetime 300; }; }; 3. Make sure radvd starts at boot and start it now: /sbin/chkconfig radvd on /sbin/service radvd start 4. Make the initscripts signal radvd to recalculate the prefix when it changes: /etc/sysconfig/network-scripts/ifcfg-eth0: IPV6_CONTROL_RADVD=yes 5. Configure the associated routes to other 6to4 subnets to point at your LAN interfaces; this can be done automatically with IPV6TO4_ROUTING variable; please refer sysconfig.txt for details. In the particular example, above, this would be like: /etc/sysconfig/network-scripts/ifcfg-eth0: IPV6TO4_ROUTING="eth1-:1::0/64" However, please note that no global address is configured on the interface, just a route! MORE INFORMATION ---------------- http://www.bieringer.de/linux/IPv6/IPv6-HOWTO/IPv6-HOWTO.html is a good source of IPv6 related Linux-information. ftp://ftp.isi.edu/in-notes/rfc3056.txt ("Connection of IPv6 Domains via IPv4 Clouds") is the RFC about 6to4. ftp://ftp.isi.edu/in-notes/rfc3068.txt ("An Anycast Prefix for 6to4 Relay Routers") is the RFC about finding a close 6to4 relay automatically. http://www.ietf.org/internet-drafts/draft-savola-v6ops-6to4-security-02.txt ("Security Considerations and Enhancements for 6to4") explains some security considerations in 6to4.
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