diff --git a/apps/openstacknetworking/src/main/java/org/onosproject/openstacknetworking/impl/RulePopulatorUtil.java b/apps/openstacknetworking/src/main/java/org/onosproject/openstacknetworking/impl/RulePopulatorUtil.java
index 8e27762..fb42dfb 100644
--- a/apps/openstacknetworking/src/main/java/org/onosproject/openstacknetworking/impl/RulePopulatorUtil.java
+++ b/apps/openstacknetworking/src/main/java/org/onosproject/openstacknetworking/impl/RulePopulatorUtil.java
@@ -16,14 +16,30 @@
 package org.onosproject.openstacknetworking.impl;
 
 import org.onlab.packet.Ip4Address;
+import org.onlab.packet.IpAddress;
+import org.onosproject.core.ApplicationId;
 import org.onosproject.net.Device;
 import org.onosproject.net.DeviceId;
+import org.onosproject.net.behaviour.ExtensionSelectorResolver;
 import org.onosproject.net.behaviour.ExtensionTreatmentResolver;
 import org.onosproject.net.device.DeviceService;
 import org.onosproject.net.flow.instructions.ExtensionPropertyException;
 import org.onosproject.net.flow.instructions.ExtensionTreatment;
+import org.onosproject.net.driver.DriverHandler;
+import org.onosproject.net.driver.DriverService;
+import org.onosproject.net.flow.TrafficSelector;
+import org.onosproject.net.flow.TrafficTreatment;
+import org.onosproject.net.flow.criteria.ExtensionSelector;
+import org.onosproject.net.flow.criteria.ExtensionSelectorType;
+import org.onosproject.net.flow.instructions.ExtensionTreatmentType;
+import org.onosproject.net.flowobjective.DefaultForwardingObjective;
+import org.onosproject.net.flowobjective.FlowObjectiveService;
+import org.onosproject.net.flowobjective.ForwardingObjective;
 import org.slf4j.Logger;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import static org.onosproject.net.flow.instructions.ExtensionTreatmentType.ExtensionTreatmentTypes.NICIRA_SET_TUNNEL_DST;
 import static org.slf4j.LoggerFactory.getLogger;
 
@@ -35,11 +51,43 @@
     protected static final Logger log = getLogger(RulePopulatorUtil.class);
 
     private static final String TUNNEL_DST = "tunnelDst";
+    private static final String CT_FLAGS = "flags";
+    private static final String CT_ZONE = "zone";
+    private static final String CT_TABLE = "recircTable";
+    private static final String CT = "niciraCt";
+    private static final String CT_STATE = "ctState";
+    private static final String CT_STATE_MASK = "ctStateMask";
+    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 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;
+
+    // Refer to http://openvswitch.org/support/dist-docs/ovs-fields.7.txt for the values
+    public static final long CT_STATE_NONE = 0;
+    public static final long CT_STATE_NEW = 0x01;
+    public static final long CT_STATE_EST = 0x02;
+    public static final long CT_STATE_NOT_TRK = 0x20;
+    public static final long CT_STATE_TRK = 0x20;
 
     private RulePopulatorUtil() {
     }
 
     /**
+     * Returns a builder for OVS Connection Tracking feature actions.
+     *
+     * @param ds DriverService
+     * @param id DeviceId
+     * @return a builder for OVS Connection Tracking feature actions
+     */
+    public static NiriraConnTrackTreatmentBuilder niciraConnTrackTreatmentBuilder(DriverService ds, DeviceId id) {
+        return new NiriraConnTrackTreatmentBuilder(ds, id);
+    }
+
+    /**
      * Returns tunnel destination extension treatment object.
      *
      * @param deviceService driver service
@@ -51,13 +99,11 @@
                                                     DeviceId deviceId,
                                                     Ip4Address remoteIp) {
         Device device = deviceService.getDevice(deviceId);
-        if (device == null) {
-            return null;
-        }
-        if (!device.is(ExtensionTreatmentResolver.class)) {
+        if (device != null && !device.is(ExtensionTreatmentResolver.class)) {
             log.error("The extension treatment is not supported");
             return null;
         }
+
         ExtensionTreatmentResolver resolver = device.as(ExtensionTreatmentResolver.class);
         ExtensionTreatment treatment = resolver.getExtensionInstruction(NICIRA_SET_TUNNEL_DST.type());
         try {
@@ -68,4 +114,256 @@
             return null;
         }
     }
+
+    /**
+     * Builds OVS ConnTrack matches.
+     *
+     * @param driverService driver service
+     * @param deviceId device ID
+     * @param ctState connection tracking sate masking value
+     * @param ctSateMask connection tracking sate masking value
+     * @return OVS ConnTrack extension match
+     */
+    public static ExtensionSelector buildCtExtensionSelector(DriverService driverService, DeviceId deviceId,
+                                                             long ctState, long ctSateMask) {
+        DriverHandler handler = driverService.createHandler(deviceId);
+        ExtensionSelectorResolver esr = handler.behaviour(ExtensionSelectorResolver.class);
+
+        ExtensionSelector extensionSelector = esr.getExtensionSelector(
+                ExtensionSelectorType.ExtensionSelectorTypes.NICIRA_MATCH_CONNTRACK_STATE.type());
+        try {
+            extensionSelector.setPropertyValue(CT_STATE, ctState);
+            extensionSelector.setPropertyValue(CT_STATE_MASK, ctSateMask);
+        } catch (Exception e) {
+            log.error("Failed to set nicira match CT state");
+            return null;
+        }
+
+        return extensionSelector;
+    }
+
+    /**
+     * Adds flow rules with the supplied information.
+     *
+     * @param flowObjectiveService flow objective service
+     * @param appId application id
+     * @param deviceId device id to remove this flow rule
+     * @param selector traffic selector
+     * @param treatment traffic treatment
+     * @param flag flag
+     * @param priority priority
+     * @param install populate flows if true, remove them otherwise
+     */
+    public static void setRule(FlowObjectiveService flowObjectiveService,
+                               ApplicationId appId,
+                               DeviceId deviceId,
+                               TrafficSelector selector,
+                               TrafficTreatment treatment,
+                               ForwardingObjective.Flag flag,
+                               int priority,
+                               boolean install) {
+        ForwardingObjective.Builder foBuilder = DefaultForwardingObjective.builder()
+                .withSelector(selector)
+                .withTreatment(treatment)
+                .withFlag(flag)
+                .withPriority(priority)
+                .fromApp(appId);
+
+        if (install) {
+            flowObjectiveService.forward(deviceId, foBuilder.add());
+        } else {
+            flowObjectiveService.forward(deviceId, foBuilder.remove());
+        }
+    }
+
+    /**
+     * Computes ConnTack State flag values.
+     *
+     * @param isTracking true for +trk, false for -trk
+     * @param isNew true for +new, false for nothing
+     * @param isEstablished true for +est, false for nothing
+     * @return ConnTrack State flags
+     */
+    public static long computeCtStateFlag(boolean isTracking, boolean isNew, boolean isEstablished) {
+        long ctMaskFlag = 0x00;
+
+        if (isTracking) {
+            ctMaskFlag = ctMaskFlag | CT_STATE_TRK;
+        }
+
+        if (isNew) {
+            ctMaskFlag = ctMaskFlag | CT_STATE_TRK;
+            ctMaskFlag = ctMaskFlag | CT_STATE_NEW;
+        }
+
+        if (isEstablished) {
+            ctMaskFlag = ctMaskFlag | CT_STATE_TRK;
+            ctMaskFlag = ctMaskFlag | CT_STATE_EST;
+        }
+
+        return ctMaskFlag;
+    }
+
+    /**
+     * Computes ConnTrack State mask values.
+     *
+     * @param isTracking true for setting +trk/-trk value, false for otherwise
+     * @param isNew true for setting +new value, false for otherwise
+     * @param isEstablished true for setting +est value, false for otherwise
+     * @return ConnTrack State Mask value
+     */
+    public static long computeCtMaskFlag(boolean isTracking, boolean isNew, boolean isEstablished) {
+        long ctMaskFlag = 0x00;
+
+        if (isTracking) {
+            ctMaskFlag = ctMaskFlag | CT_STATE_TRK;
+        }
+
+        if (isNew) {
+            ctMaskFlag = ctMaskFlag | CT_STATE_TRK;
+            ctMaskFlag = ctMaskFlag | CT_STATE_NEW;
+        }
+
+        if (isEstablished) {
+            ctMaskFlag = ctMaskFlag | CT_STATE_TRK;
+            ctMaskFlag = ctMaskFlag | CT_STATE_EST;
+        }
+
+        return ctMaskFlag;
+    }
+
+    /**
+     * Builder class for OVS Connection Tracking feature actions.
+     */
+    public static final class NiriraConnTrackTreatmentBuilder {
+
+        private DriverService driverService;
+        private DeviceId deviceId;
+        private IpAddress natAddress = null;
+        private int zone;
+        private boolean commit;
+        private short table = -1;
+        private boolean natAction;
+
+
+        private NiriraConnTrackTreatmentBuilder(DriverService driverService, DeviceId deviceId) {
+            this.driverService = driverService;
+            this.deviceId = deviceId;
+        }
+
+        /**
+         * Sets commit flag.
+         *
+         * @param c true if commit, false if not.
+         * @return NiriraConnTrackTreatmentBuilder object
+         */
+        public NiriraConnTrackTreatmentBuilder commit(boolean c) {
+            this.commit = c;
+            return this;
+        }
+
+        /**
+         * Sets zone number.
+         *
+         * @param z zone number
+         * @return NiriraConnTrackTreatmentBuilder object
+         */
+        public NiriraConnTrackTreatmentBuilder zone(int z) {
+            this.zone = z;
+            return this;
+        }
+
+        /**
+         * Sets recirculation table number.
+         *
+         * @param t table number to restart
+         * @return NiriraConnTrackTreatmentBuilder object
+         */
+        public NiriraConnTrackTreatmentBuilder table(short t) {
+            this.table = t;
+            return this;
+        }
+
+        /**
+         * Sets IP address for NAT.
+         *
+         * @param ip NAT IP address
+         * @return NiriraConnTrackTreatmentBuilder object
+         */
+        public NiriraConnTrackTreatmentBuilder natIp(IpAddress ip) {
+            this.natAddress = ip;
+            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) {
+            this.natAction = nat;
+            return this;
+        }
+
+        /**
+         * Builds extension treatment for OVS ConnTack and NAT feature.
+         *
+         * @return ExtensionTreatment object
+         */
+        public ExtensionTreatment build() {
+            DriverHandler handler = driverService.createHandler(deviceId);
+            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 {
+                    natTreatment.setPropertyValue(CT_FLAGS, 0);
+                    natTreatment.setPropertyValue(CT_PRESENT_FLAGS, 0);
+                }
+            } catch (Exception e) {
+                log.error("Failed to set NAT due to error : {}", e.getMessage());
+                return null;
+            }
+
+            ExtensionTreatment ctTreatment
+                    = etr.getExtensionInstruction(ExtensionTreatmentType.ExtensionTreatmentTypes.NICIRA_CT.type());
+            try {
+                List<ExtensionTreatment> nat = new ArrayList<>();
+                if (natAction) {
+                    nat.add(natTreatment);
+                }
+                ctTreatment.setPropertyValue(CT_FLAGS, commit ? 1 : 0);
+                ctTreatment.setPropertyValue(CT_ZONE, zone);
+                ctTreatment.setPropertyValue(CT_TABLE, table > -1 ? table : 0xff);
+                ctTreatment.setPropertyValue("nestedActions", nat);
+            } catch (Exception e) {
+                log.error("Failed to set CT due to error : {}", e.getMessage());
+                return null;
+            }
+
+            return ctTreatment;
+        }
+
+        private int buildPresentFlag(boolean isPortPresent, boolean isAddressPresent) {
+
+            int presentFlag = 0;
+
+            if (isPortPresent) {
+                presentFlag = presentFlag | 1 << PORT_MIN_FLAG | 1 << PORT_MAX_FLAG;
+            }
+
+            if (isAddressPresent) {
+                presentFlag =  1 << ADDRESS_MIN_FLAG | 1 << ADDRESS_MAX_FLAG;
+            }
+
+            return presentFlag;
+        }
+    }
 }