help: Disable IPv6 operation on interface when DAD fails on LL addr

# Enable strict DAD behavior.  Disable IPv6 operation on an interface
# if DAD fails on the EUI-64 based link-local address.
#
create:
    sudo sh -c "echo 2 > /proc/sys/net/ipv6/conf/all/accept_dad"
    sudo sh -c "echo 2 > /proc/sys/net/ipv6/conf/default/accept_dad"
    for ifname in /sys/class/net/eth* ; do
	if [ -d $ifname ]; then
	    ifname=${ifname#/sys/class/net/}
       	    sudo sh -c "echo 2 > /proc/sys/net/ipv6/conf/$ifname/accept_dad"
	fi
    done


# Revert back to liberal DAD behavior
delete: 
    sudo sh -c "echo 1 > /proc/sys/net/ipv6/conf/all/accept_dad"
    sudo sh -c "echo 1 > /proc/sys/net/ipv6/conf/default/accept_dad"
    for ifname in /sys/class/net/eth* ; do
	if [ -d $ifname ]; then
	    ifname=${ifname#/sys/class/net/}
       	    sudo sh -c "echo 1 > /proc/sys/net/ipv6/conf/$ifname/accept_dad"
	fi
    done
