Debian, DHCP and IPv6

It was big surprise for that in Debian /etc/network/interface you cannot us iface ethX inet6 dhcp option to use DHCPv6 client to set IP address. If you need IPv6 address from DHCP server, you should can either define interface manually:

iface eth1 inet6 manual
 up /sbin/ip link set eth1 up
 post-up /etc/init.d/wide-dhcpv6-client start
 pre-down /etc/init.d/wide-dhcpv6-client stop
 down /sbin/ip link set eth1 down

or plug it into IPv4 definition (i.e. inet dhcp).

inet dhcp
iface eth1 inet dhcp
 post-up /etc/init.d/wide-dhcpv6-client start
 pre-down /etc/init.d/wide-dhcpv6-client stop