ip6config(8)

NAME
ip6config - Configure IPv6 and 6to4 IPv6 tunnelling

SYNOPSIS
ip6config [-h] command interface

DESCRIPTION
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 settings. 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 be configured.

start-stf
    Configure 6to4 IPv6. The stf(4) interface is configured, and a default route to a remote 6to4 gateway is established. 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 advertizements, 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.

REQUIREMENTS
Besides IPv4 connectivity, you need support for IPv6 and the stf(4) device in your kernel. This is provided beginning with Darwin Kernel Version 6.0.

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 rtadvd-start command!

CONFIGURATION
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 ethernet.

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 interface's addresses.

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 anycast service defined in RFC 3068. Other possible values are given in the example config file.

SEE ALSO
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.

HISTORY
The ip6config 6to4 utility and manpage portions were written by Hubert Feyrer <hubert@feyrer.de> for NetBSD.