Disable accept_dad on all interfaces except external

Disable duplicate address detection on all interfaces except
the external interface (eth1). This change is to fix race conditions
with bird6 binding to tenant networks as well as SSHD binding to
the mgmt interface on boot.

scripts/create-akanda-raw-image.sh

@@ -139,7 +139,8 @@ echo "[*] Add some stuff to sysctl.conf"
 cat > /etc/sysctl.conf <<EOF
 net.ipv4.ip_forward=1
 net.ipv6.conf.all.forwarding=1
-net.ipv6.conf.eth0.accept_dad=0
+net.ipv6.conf.all.accept_dad=0
+net.ipv6.conf.eth1.accept_dad=1
 net.ipv4.conf.all.arp_announce=2
 EOF