ip6config(8) BSD System Manager's Manual ip6config(8)
ip6config -- Configure IPv6 and 6to4 IPv6 tunnelling
ip6config [-h] command interface
The ip6config script can be used to start up or shut down IPv6 on active
interfaces. It can also be used to configure a 6to4 tunnel and start or
stop router advertisement.
When IPv6 is enabled on an interface the protocol is attached to the
interface, at which point the default settings in the kernel allow it to
acquire a link-local address and listen for router advertisements.
6to4 is a mechanism by which your IPv6 address(es) are derived from an
assigned IPv4 address, and which involves automatic tunnelling to one or
more remove 6to4 hubs, which will then forward your v6 packets on the
6bone etc. Replies are routed back to you over IPv4 via (possibly) other
6to4 capable remote gateways. As such, IPv6-in-IPv4-encapsulated packets
are accepted from all v4-hosts.
From your (single) IPv4 address, you get a whole IPv6 /48 network, which
allows you to split your network in 2^16 subnets, with 2^64 hosts each.
You need to setup routing for your internal network properly, help is
provided for setting up the border router here.
This script takes the burden to calculate your IPv6 address from existing
IPv4 address and runs the commands to setup (and tear down) automatic
6to4 IPv6 tunnelling.
Finally, router advertisement for an internal network can be started and
stopped. This uses sysctl to set net.inet6.ip6.forwarding and
net.inet6.ip6.accept_rtadv to the proper values for routing.
Possible options are:
-h Show usage.
Possible commands are:
start-v6 Start IPv6 on given interface using default kernel set-
tings. Attaches protocol to the interface. If interface is
"all", all valid interfaces will be configured.
stop-v6 Stop IPv6 on given interface. Detaches protocol from the
interface. If interface is "all", all valid interfaces will
start-stf Configure 6to4 IPv6. The stf(4) interface is configured,
and a default route to a remote 6to4 gateway is estab-
lished. In addition, the internal network interface is
assigned an address.
stop-stf Stops 6to4 IPv6. All addresses are removed from the stf(4)
device, and the default route is removed.
start-rtadvd Starts router advertizement and IPv6 packet forwarding,
turning the machine into a IPv6 router. rtadvd(8) is
invoked with a custom config file created under /var/run.
Clients just need to be told to accept router advertize-
ments, i.e. the 'net.inet6.ip6.accept_rtadv' sysctl needs
to be set to '1'. You can arrange that by setting
``ip6mode=autohost'' in /etc/rc.conf.
stop-rtadvd Stops router advertizement and IPv6 packet forwarding.
rtadvd(8) is stopped, and the rtadvd.conf(5) config file is
removed from /var/run.
Besides IPv4 connectivity, you need support for IPv6 and the stf(4)
device in your kernel. This is provided beginning with Darwin Kernel Ver-
No special values are needed in /etc/rc.conf to run this script, but see
comment on setting up IPv6-clients 'behind' your 6to4 router for the
The default IPv6 configuration for an interface assigns a link-local
address to it and sets the interface to receive router advertisements.
No further configuration is necessary for basic functionality. However,
various settings can be modified by using sysctl.
The ip6config script reads its 6to4 configuration from a config file
named 6to4.conf. The 6to4.conf file is in perl(1) syntax, and contains
several variables that can be tuned to adjust your setup.
in_if The inside interface. If non-empty, this interface is
assigned the IPv6 address 2002:x:x:v6_innernet:hostbits6,
see below. This is only useful on machines that have more
than one network interface, e.g. with a modem and a local
v6_net The subnet address you want to use on the address of your
outbound interface. Defaults to ``1''.
v6_innernet The subnet address you want to use on the address of your
inbound interface. Defaults to ``2''.
hostbits6 The lower 64 bits of both the inbound and outbound inter-
peer Name of the remote 6to4 server that'll take our IPv6-in-
IPv4 encapsulated packets and route them on via IPv6. A
special value of ``6to4-anycast'' can be used for the any-
cast service defined in RFC 3068. Other possible values
are given in the example config file.
stf(4), ``6to4 IPv6 Explained'' at http://www.feyrer.de/NetBSD/6to4.html,
NetBSD IPv6 Documentation at
http://www.netbsd.org/Documentation/network/ipv6/, RFC 3068.
The ip6config 6to4 utility and manpage portions were written by Hubert
Feyrer <hubertATfeyrer.de> for NetBSD.
BSD May 21, 2002 BSD