diff -up dhcp-4.1.1/client/scripts/linux.orig dhcp-4.1.1/client/scripts/linux
--- dhcp-4.1.1/client/scripts/linux.orig	2010-04-30 15:54:43.000000000 +0200
+++ dhcp-4.1.1/client/scripts/linux	2010-04-30 15:54:43.000000000 +0200
@@ -240,8 +240,30 @@ if [ x$reason = xBOUND6 ] ; then
     exit_with_hooks 2;
   fi
 
-  ${ip} -f inet6 addr add ${new_ip6_address}/${new_ip6_prefixlen} \
-	dev ${interface} scope global
+  ${ip} -6 addr add ${new_ip6_address}/${new_ip6_prefixlen} \
+        dev ${interface} scope global
+
+  # repeatedly test whether newly added address passed
+  # duplicate address detection (DAD)
+  for i in $(seq 5); do
+      sleep 1 # give the DAD some time
+
+      # tentative flag = DAD is still not complete or failed
+      duplicate=$(${ip} -6 addr show dev ${interface} tentative \
+                    | grep ${new_ip6_address}/${new_ip6_prefixlen})
+
+      # if there's no tentative flag, address passed DAD
+      if [ -z "${duplicate}" ]; then
+          break
+      fi
+  done
+
+  # if there's still tentative flag = address didn't pass DAD = 
+  # = it's duplicate = remove it
+  if [ -n "${duplicate}" ]; then
+      ${ip} -6 addr del ${new_ip6_address}/${new_ip6_prefixlen} dev ${interface}
+      exit_with_hooks 3
+  fi
 
   # Check for nameserver options.
   make_resolv_conf