diff --git a/firewall/firewall-add b/firewall/firewall-add
index d82c296..021baac 100755
--- a/firewall/firewall-add
+++ b/firewall/firewall-add
@@ -244,6 +244,11 @@ fi
 
 
 prerouting() {
+	if [ "$SOURCE_IP" != "" ]; then
+		if [ "$SOURCE_PORT" != "" ]; then
+			if [ "$TARGET_IP" != "" ]; then
+				if [ "$TARGET_PORT" != "" ]; then
+
 	LINES=$($IPTABLES -w -L --line-number -n | grep DNAT | grep $SOURCE_PORT |grep $TARGET_IP |grep $TARGET_PORT |grep $COMMENT | awk '{print $1}'| tac)
 	debug "Previous prerouting lines: "$LINES
 	# DELETE UNECESSARY LINES FROM PREVIOUS RULES
@@ -257,6 +262,10 @@ prerouting() {
 
 	debug "$IPTABLES -I PREROUTING -d $SOURCE_IP -p $PROTOCOL --dport $SOURCE_PORT -m comment --comment $COMMENT -j DNAT --to $TARGET_IP:$TARGET_PORT"
 	$IPTABLES -w -I PREROUTING -d $SOURCE_IP -p $PROTOCOL --dport $SOURCE_PORT -m comment --comment "$COMMENT" -j DNAT --to $TARGET_IP:$TARGET_PORT
+				fi
+			fi
+		fi
+	fi
 }
 
 postrouting() {