diff --git a/Shorewall-common/releasenotes.txt b/Shorewall-common/releasenotes.txt
index b05e3c054..f8cb72b6a 100644
--- a/Shorewall-common/releasenotes.txt
+++ b/Shorewall-common/releasenotes.txt
@@ -7,7 +7,7 @@ Shorewall 4.3.3
 
    Minimun system requirements:
 
-   - Kernel 2.6.20 or later with 2.6.25 or later strongly recommended.
+   - Kernel 2.6.23 or later with 2.6.25 or later strongly recommended.
    - iptables 1.4.0 or later with 1.4.1 strongly recommended.
    - Perl 5.10 if you wish to use DNS names in your IPv6 config files. 
      In that case you will also have to install Perl Socket6 support.
@@ -31,6 +31,10 @@ Other changes in 4.3.3
 
 3)  Traffic shaping is now enabled in Shorewall6. See below.
 
+4)  Shorewall6 and Shorewall6 Lite now check the kernel version during
+    'start' processing. If the kernel version is less than 2.6.25, a 
+    fatal error is generated.
+
 Migration Issues.
 
    None.
diff --git a/Shorewall-perl/prog.footer6 b/Shorewall-perl/prog.footer6
index 90dbd05bc..4060c0431 100644
--- a/Shorewall-perl/prog.footer6
+++ b/Shorewall-perl/prog.footer6
@@ -64,137 +64,143 @@ COMMAND="$1"
 
 [ -n "${PRODUCT:=Shorewall6}" ]
 
-case "$COMMAND" in
-    start)
-	[ $# -ne 1 ] && usage 2
-	if shorewall6_is_started; then
-	    error_message "$PRODUCT is already Running"
+kernel=$(printf "%2d%02d%02d\n" $(echo $(uname -r) 2> /dev/null | sed 's/-.*//' | tr '.' ' ' ) | head -n1)
+if [ $kernel -lt 20625 ]; then
+    error_message "ERROR: $PRODUCT requires Linux kernel 2.6.25 or later"
+    status=2
+else 
+    case "$COMMAND" in
+	start)
+	    [ $# -ne 1 ] && usage 2
+	    if shorewall6_is_started; then
+		error_message "$PRODUCT is already Running"
+		status=0
+	    else
+		progress_message3 "Starting $PRODUCT...."
+		define_firewall
+		status=$?
+		[ -n "$SUBSYSLOCK" -a $status -eq 0 ] && touch $SUBSYSLOCK
+		progress_message3 "done."
+	    fi
+	    ;;
+	stop)
+	    [ $# -ne 1 ] && usage 2
+	    progress_message3 "Stopping $PRODUCT...."
+	    stop_firewall
 	    status=0
-	else
-	    progress_message3 "Starting $PRODUCT...."
-	    define_firewall
-	    status=$?
-	    [ -n "$SUBSYSLOCK" -a $status -eq 0 ] && touch $SUBSYSLOCK
+	    [ -n "$SUBSYSLOCK" ] && rm -f $SUBSYSLOCK
 	    progress_message3 "done."
-	fi
-	;;
-    stop)
-	[ $# -ne 1 ] && usage 2
-	progress_message3 "Stopping $PRODUCT...."
-	stop_firewall
-	status=0
-	[ -n "$SUBSYSLOCK" ] && rm -f $SUBSYSLOCK
-	progress_message3 "done."
-	;;
-    reset)
-	if ! shorewall6_is_started ; then
-	    error_message "$PRODUCT is not running"
-	    status=2
-	elif [ $# -eq 1 ]; then
-	    $IP6TABLES -Z
-	    $IP6TABLES -t mangle -Z
-	    date > ${VARDIR}/restarted
-	    status=0
-	    progress_message3 "$PRODUCT Counters Reset"
-	else
-	    shift
-	    status=0
-	    for chain in $@; do
-		if chain_exists $chain; then
-		    if qt $IP6TABLES -Z $chain; then
-			progress_message3 "Filter $chain Counters Reset"
+	    ;;
+	reset)
+	    if ! shorewall6_is_started ; then
+		error_message "$PRODUCT is not running"
+		status=2
+	    elif [ $# -eq 1 ]; then
+		$IP6TABLES -Z
+		$IP6TABLES -t mangle -Z
+		date > ${VARDIR}/restarted
+		status=0
+		progress_message3 "$PRODUCT Counters Reset"
+	    else
+		shift
+		status=0
+		for chain in $@; do
+		    if chain_exists $chain; then
+			if qt $IP6TABLES -Z $chain; then
+			    progress_message3 "Filter $chain Counters Reset"
+			else
+			    error_message "ERROR: Reset of chain $chain failed"
+			    status=2
+			    break
+			fi
 		    else
-			error_message "ERROR: Reset of chain $chain failed"
-			status=2
-			break
+			error_message "WARNING: Filter Chain $chain does not exist"
 		    fi
-		else
-		    error_message "WARNING: Filter Chain $chain does not exist"
-		fi
-	    done
-	fi
-	;;
-    restart)
-	[ $# -ne 1 ] && usage 2
-	if shorewall6_is_started; then
-	    progress_message3 "Restarting $PRODUCT...."
-	else
-	    error_message "$PRODUCT is not running"
-	    progress_message3 "Starting $PRODUCT...."
-	fi
-
-	define_firewall
-	status=$?
-	if [ -n "$SUBSYSLOCK" ]; then
- 	    [ $status -eq 0 ] && touch $SUBSYSLOCK || rm -f $SUBSYSLOCK
-        fi
-	progress_message3 "done."
-	;;
-    refresh)
-	[ $# -ne 1 ] && usage 2
-	if shorewall6_is_started; then
-	    progress_message3 "Refreshing $PRODUCT...."
+		done
+	    fi
+	    ;;
+	restart)
+	    [ $# -ne 1 ] && usage 2
+	    if shorewall6_is_started; then
+		progress_message3 "Restarting $PRODUCT...."
+	    else
+		error_message "$PRODUCT is not running"
+		progress_message3 "Starting $PRODUCT...."
+	    fi
+	    
 	    define_firewall
 	    status=$?
+	    if [ -n "$SUBSYSLOCK" ]; then
+ 		[ $status -eq 0 ] && touch $SUBSYSLOCK || rm -f $SUBSYSLOCK
+            fi
 	    progress_message3 "done."
-	else
-	    echo "$PRODUCT is not running" >&2
-	    status=2
-	fi
-	;;
-    restore)
-	[ $# -ne 1 ] && usage 2
-	define_firewall
-	status=$?
-	if [ -n "$SUBSYSLOCK" ]; then
- 	    [ $status -eq 0 ] && touch $SUBSYSLOCK || rm -f $SUBSYSLOCK
-        fi
-	;;
-    clear)
-	[ $# -ne 1 ] && usage 2
-	progress_message3 "Clearing $PRODUCT...."
-	clear_firewall
-	status=0
-	[ -n "$SUBSYSLOCK" ] && rm -f $SUBSYSLOCK
-	progress_message3 "done."
-	;;
-    status)
-	[ $# -ne 1 ] && usage 2
-	echo "$PRODUCT-$VERSION Status at $HOSTNAME - $(date)"
-	echo
-	if shorewall6_is_started; then
-	    echo "$PRODUCT is running"
+	    ;;
+	refresh)
+	    [ $# -ne 1 ] && usage 2
+	    if shorewall6_is_started; then
+		progress_message3 "Refreshing $PRODUCT...."
+		define_firewall
+		status=$?
+		progress_message3 "done."
+	    else
+		echo "$PRODUCT is not running" >&2
+		status=2
+	    fi
+	    ;;
+	restore)
+	    [ $# -ne 1 ] && usage 2
+	    define_firewall
+	    status=$?
+	    if [ -n "$SUBSYSLOCK" ]; then
+ 		[ $status -eq 0 ] && touch $SUBSYSLOCK || rm -f $SUBSYSLOCK
+            fi
+	    ;;
+	clear)
+	    [ $# -ne 1 ] && usage 2
+	    progress_message3 "Clearing $PRODUCT...."
+	    clear_firewall
 	    status=0
-	else
-	    echo "$PRODUCT is stopped"
-	    status=4
-	fi
-
-	if [ -f ${VARDIR}/state ]; then
-	    state="$(cat ${VARDIR}/state)"
-	    case $state in
-		Stopped*|Clear*)
-		    status=3
-		    ;;
-	    esac
-	else
-	    state=Unknown
-	fi
-	echo "State:$state"
-	echo
-	;;
-    version)
-	[ $# -ne 1 ] && usage 2
-	echo $VERSION
-	status=0
-	;;
-    help)
-	[ $# -ne 1 ] && usage 2
-	usage 0
-	;;
-    *)
-	usage 2
-	;;
-esac
+	    [ -n "$SUBSYSLOCK" ] && rm -f $SUBSYSLOCK
+	    progress_message3 "done."
+	    ;;
+	status)
+	    [ $# -ne 1 ] && usage 2
+	    echo "$PRODUCT-$VERSION Status at $HOSTNAME - $(date)"
+	    echo
+	    if shorewall6_is_started; then
+		echo "$PRODUCT is running"
+		status=0
+	    else
+		echo "$PRODUCT is stopped"
+		status=4
+	    fi
+	    
+	    if [ -f ${VARDIR}/state ]; then
+		state="$(cat ${VARDIR}/state)"
+		case $state in
+		    Stopped*|Clear*)
+			status=3
+			;;
+		esac
+	    else
+		state=Unknown
+	    fi
+	    echo "State:$state"
+	    echo
+	    ;;
+	version)
+	    [ $# -ne 1 ] && usage 2
+	    echo $VERSION
+	    status=0
+	    ;;
+	help)
+	    [ $# -ne 1 ] && usage 2
+	    usage 0
+	    ;;
+	*)
+	    usage 2
+	    ;;
+    esac
+fi
 
 exit $status