provide upgrade path

debian/changelog

@@ -2,6 +2,7 @@ dns-flood-detector (1.12-2) unstable; urgency=low
 
   * some cosmetic fixes to init script
   * make start-stop-daemon working instead of using kill (Closes: #431676).
+  * providing upgrade path via prerm
   * drop own maintainers scripts and make again use of debhelper
 
  -- Jan Wagner <waja@cyconet.org>  Wed, 04 Jul 2007 12:29:06 +0200

debian/prerm

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+
+if [ "$1" = "upgrade" ] && [ "$2" ] && dpkg --compare-versions "$2" <= "1.12-1"; then
+	ps aux | grep /usr/bin/dns-flood-detector | head -1 | awk '{ print $2 }' > /var/run/dns-flood-detector.pid
+fi
+#DEBHLPER#