diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/RulePopulatorUtil.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/RulePopulatorUtil.java
index b5abaec..dace1ff 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/RulePopulatorUtil.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/util/RulePopulatorUtil.java
@@ -17,6 +17,7 @@
 
 import org.onlab.packet.Ip4Address;
 import org.onlab.packet.IpAddress;
+import org.onlab.packet.TpPort;
 import org.onosproject.net.Device;
 import org.onosproject.net.DeviceId;
 import org.onosproject.net.behaviour.ExtensionSelectorResolver;
@@ -53,11 +54,22 @@
     private static final String CT_PRESENT_FLAGS = "presentFlags";
     private static final String CT_IPADDRESS_MIN = "ipAddressMin";
     private static final String CT_IPADDRESS_MAX = "ipAddressMax";
+    private static final String CT_PORT_MIN = "portMin";
+    private static final String CT_PORT_MAX = "portMax";
+    private static final String CT_NESTED_ACTIONS = "nestedActions";
 
-    private static final int ADDRESS_MIN_FLAG = 0;
-    private static final int ADDRESS_MAX_FLAG = 1;
-    private static final int PORT_MIN_FLAG = 2;
-    private static final int PORT_MAX_FLAG = 3;
+    public static final int CT_NAT_SRC_FLAG = 0;
+    public static final int CT_NAT_DST_FLAG = 1;
+    public static final int CT_NAT_PERSISTENT_FLAG = 2;
+    public static final int CT_NAT_PROTO_HASH_FLAG = 3;
+    public static final int CT_NAT_PROTO_RANDOM_FLAG = 4;
+
+    private static final int ADDRESS_V4_MIN_FLAG = 0;
+    private static final int ADDRESS_V4_MAX_FLAG = 1;
+    private static final int ADDRESS_V6_MIN_FLAG = 2;
+    private static final int ADDRESS_V6_MAX_FLAG = 3;
+    private static final int PORT_MIN_FLAG = 4;
+    private static final int PORT_MAX_FLAG = 5;
 
     // Refer to http://openvswitch.org/support/dist-docs/ovs-fields.7.txt for the values
     public static final long CT_STATE_NONE = 0;
@@ -76,9 +88,9 @@
      * @param id DeviceId
      * @return a builder for OVS Connection Tracking feature actions
      */
-    public static NiriraConnTrackTreatmentBuilder
+    public static NiciraConnTrackTreatmentBuilder
                     niciraConnTrackTreatmentBuilder(DriverService ds, DeviceId id) {
-        return new NiriraConnTrackTreatmentBuilder(ds, id);
+        return new NiciraConnTrackTreatmentBuilder(ds, id);
     }
 
     /**
@@ -207,18 +219,21 @@
     /**
      * Builder class for OVS Connection Tracking feature actions.
      */
-    public static final class NiriraConnTrackTreatmentBuilder {
+    public static final class NiciraConnTrackTreatmentBuilder {
 
         private DriverService driverService;
         private DeviceId deviceId;
         private IpAddress natAddress = null;
+        private TpPort natPortMin = null;
+        private TpPort natPortMax = null;
         private int zone;
         private boolean commit;
         private short table = -1;
         private boolean natAction;
+        private int natFlag;
 
-
-        private NiriraConnTrackTreatmentBuilder(DriverService driverService,
+        // private constructor
+        private NiciraConnTrackTreatmentBuilder(DriverService driverService,
                                                 DeviceId deviceId) {
             this.driverService = driverService;
             this.deviceId = deviceId;
@@ -230,7 +245,7 @@
          * @param c true if commit, false if not.
          * @return NiriraConnTrackTreatmentBuilder object
          */
-        public NiriraConnTrackTreatmentBuilder commit(boolean c) {
+        public NiciraConnTrackTreatmentBuilder commit(boolean c) {
             this.commit = c;
             return this;
         }
@@ -241,7 +256,7 @@
          * @param z zone number
          * @return NiriraConnTrackTreatmentBuilder object
          */
-        public NiriraConnTrackTreatmentBuilder zone(int z) {
+        public NiciraConnTrackTreatmentBuilder zone(int z) {
             this.zone = z;
             return this;
         }
@@ -252,7 +267,7 @@
          * @param t table number to restart
          * @return NiriraConnTrackTreatmentBuilder object
          */
-        public NiriraConnTrackTreatmentBuilder table(short t) {
+        public NiciraConnTrackTreatmentBuilder table(short t) {
             this.table = t;
             return this;
         }
@@ -263,18 +278,56 @@
          * @param ip NAT IP address
          * @return NiriraConnTrackTreatmentBuilder object
          */
-        public NiriraConnTrackTreatmentBuilder natIp(IpAddress ip) {
+        public NiciraConnTrackTreatmentBuilder natIp(IpAddress ip) {
             this.natAddress = ip;
             return this;
         }
 
         /**
+         * Sets min port for NAT.
+         *
+         * @param port port number
+         * @return NiciraConnTrackTreatmentBuilder object
+         */
+        public NiciraConnTrackTreatmentBuilder natPortMin(TpPort port) {
+            this.natPortMin = port;
+            return this;
+        }
+
+        /**
+         * Sets max port for NAT.
+         *
+         * @param port port number
+         * @return NiciraConnTrackTreatmentBuilder object
+         */
+        public NiciraConnTrackTreatmentBuilder natPortMax(TpPort port) {
+            this.natPortMax = port;
+            return this;
+        }
+
+        /**
+         * Sets NAT flags.
+         * SRC NAT: 1 << 0
+         * DST NAT: 1 << 1
+         * PERSISTENT NAT: 1 << 2
+         * PROTO_HASH NAT: 1 << 3
+         * PROTO_RANDOM NAT : 1 << 4
+         *
+         * @param flag flag value
+         * @return NiciraConnTrackTreatmentBuilder object
+         */
+        public NiciraConnTrackTreatmentBuilder natFlag(int flag) {
+            this.natFlag = 1 << flag;
+            return this;
+        }
+
+        /**
          * Sets the flag for NAT action.
          *
          * @param nat nat action is included if true, no nat action otherwise
          * @return NiriraConnTrackTreatmentBuilder object
          */
-        public NiriraConnTrackTreatmentBuilder natAction(boolean nat) {
+        public NiciraConnTrackTreatmentBuilder natAction(boolean nat) {
             this.natAction = nat;
             return this;
         }
@@ -286,21 +339,37 @@
          */
         public ExtensionTreatment build() {
             DriverHandler handler = driverService.createHandler(deviceId);
-            ExtensionTreatmentResolver etr = handler.behaviour(ExtensionTreatmentResolver.class);
+            ExtensionTreatmentResolver etr =
+                    handler.behaviour(ExtensionTreatmentResolver.class);
 
             ExtensionTreatment natTreatment = etr.getExtensionInstruction(
                     ExtensionTreatmentType.ExtensionTreatmentTypes.NICIRA_NAT.type());
             try {
-                if (natAddress != null) {
-                    natTreatment.setPropertyValue(CT_FLAGS, 1);
-                    natTreatment.setPropertyValue(CT_PRESENT_FLAGS,
-                            buildPresentFlag(false, true));
-                    natTreatment.setPropertyValue(CT_IPADDRESS_MIN, natAddress);
-                    natTreatment.setPropertyValue(CT_IPADDRESS_MAX, natAddress);
-                } else {
+
+                if (natAddress == null && natPortMin == null && natPortMax == null) {
                     natTreatment.setPropertyValue(CT_FLAGS, 0);
                     natTreatment.setPropertyValue(CT_PRESENT_FLAGS, 0);
+                } else {
+                    natTreatment.setPropertyValue(CT_FLAGS, this.natFlag);
+
+                    natTreatment.setPropertyValue(CT_PRESENT_FLAGS,
+                            buildPresentFlag((natPortMin != null && natPortMax != null),
+                                    natAddress != null));
                 }
+
+                if (natAddress != null) {
+                    natTreatment.setPropertyValue(CT_IPADDRESS_MIN, natAddress);
+                    natTreatment.setPropertyValue(CT_IPADDRESS_MAX, natAddress);
+                }
+
+                if (natPortMin != null) {
+                    natTreatment.setPropertyValue(CT_PORT_MIN, natPortMin.toInt());
+                }
+
+                if (natPortMax != null) {
+                    natTreatment.setPropertyValue(CT_PORT_MAX, natPortMax.toInt());
+                }
+
             } catch (Exception e) {
                 log.error("Failed to set NAT due to error : {}", e);
                 return null;
@@ -316,7 +385,7 @@
                 ctTreatment.setPropertyValue(CT_FLAGS, commit ? 1 : 0);
                 ctTreatment.setPropertyValue(CT_ZONE, zone);
                 ctTreatment.setPropertyValue(CT_TABLE, table > -1 ? table : 0xff);
-                ctTreatment.setPropertyValue("nestedActions", nat);
+                ctTreatment.setPropertyValue(CT_NESTED_ACTIONS, nat);
             } catch (Exception e) {
                 log.error("Failed to set CT due to error : {}", e);
                 return null;
@@ -330,11 +399,12 @@
             int presentFlag = 0;
 
             if (isPortPresent) {
-                presentFlag = presentFlag | 1 << PORT_MIN_FLAG | 1 << PORT_MAX_FLAG;
+                presentFlag = 1 << PORT_MIN_FLAG | 1 << PORT_MAX_FLAG;
             }
 
             if (isAddressPresent) {
-                presentFlag =  1 << ADDRESS_MIN_FLAG | 1 << ADDRESS_MAX_FLAG;
+                // TODO: need to support IPv6 address
+                presentFlag =  presentFlag | 1 << ADDRESS_V4_MIN_FLAG | 1 << ADDRESS_V4_MAX_FLAG;
             }
 
             return presentFlag;