| IPv6 Network - FreeBSD |
IPv6 Network - FreeBSD Several large Japanese companies started working on a joint IPv6 and IPsec implementation in 1998 as part of the KAME project. The KAME effort resulted in a very mature IPv6 protocol stack, which has been integrated into the members of the Berkeley Software Distribution family of UNIX operating systems: FreeBSD, the most widely used member of the family, as of version 4.0, NetBSD in version 1.5, and OpenBSD and BSD/OS in versions 2.7 and 4.2, respectively.
FreeBSD systems with IPv6 support in the kernel (which is the default for recent versions) have IPv6 processing and the creation of link-local addresses enabled by default, but autoconfiguration of global scope addresses that use router advertisements is disabled. To enable autoconfiguration, add the linesipv6_enable="YES"
ipv6_network_interfaces="auto"
to the file /etc/rc.conf and reboot. This syntax is confusing, because IPv6 is enabled by default, so ipv6_enable="YES" doesn’t enable it, nor does ipv6_enable="NO" disable it. Also, the list of IPv6 interfaces doesn’t really do anything under FreeBSD 5.x, but, if the previous line is also present, it tricks the FreeBSD 4.x startup scripts into setting the sysctl variable net.inet6.ip6.accept_rtadv to 1, as IPv6 processing is enabled on all interfaces regardless of whether it’s listed or not. With the new sysctl setting, global IPv6 addresses are configured for all interfaces that receive router advertisements. The most likely explanation for this way of configuration would be that at some point, functionality that used to be provided by startup scripts was moved to the kernel, but the startup scripts remained. The creation of IPv6 addresses can be monitored by using the ifconfig command, as shown in Listing 2-2. It’s not necessary to be root to run ifconfig in this way.
Listing 2-2. Using ifconfig to Monitor IPv6 Addresses on FreeBSD
# ifconfig xl0
xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 192.0.2.123 netmask 0xffffff00 broadcast 192.0.2.255
inet6 fe80::201:2ff:fe29:2640%xl0 prefixlen 64 scopeid 0x1
inet6 2001:db8:31:2:201:2ff:fe29:2640 prefixlen 64 autoconf
ether 00:01:02:29:26:40
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
The scopeid value is just a numerical reference for an interface, and it’s listed to indicate that the link-local address is only valid within the scope of this particular interface. The autoconf keyword indicates that the listed global address was autoconfigured.
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