diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index 194737a..e5380e0 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -1291,6 +1291,7 @@
             // Sometimes interfaces are gone before we get
             // to remove their rules, which generates errors.
             // Just do the best we can.
+            mBpfCoordinator.maybeDetachProgram(mIfaceName, upstreamIface);
             try {
                 mNetd.ipfwdRemoveInterfaceForward(mIfaceName, upstreamIface);
             } catch (RemoteException | ServiceSpecificException e) {
@@ -1334,6 +1335,7 @@
                     mUpstreamIfaceSet = newUpstreamIfaceSet;
 
                     for (String ifname : added) {
+                        mBpfCoordinator.maybeAttachProgram(mIfaceName, ifname);
                         try {
                             mNetd.tetherAddForward(mIfaceName, ifname);
                             mNetd.ipfwdAddInterfaceForward(mIfaceName, ifname);
diff --git a/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java b/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
index 7c52716..8df3045 100644
--- a/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
+++ b/Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java
@@ -28,6 +28,8 @@
 import static android.system.OsConstants.ETH_P_IP;
 import static android.system.OsConstants.ETH_P_IPV6;
 
+import static com.android.networkstack.tethering.BpfUtils.DOWNSTREAM;
+import static com.android.networkstack.tethering.BpfUtils.UPSTREAM;
 import static com.android.networkstack.tethering.TetheringConfiguration.DEFAULT_TETHER_OFFLOAD_POLL_INTERVAL_MS;
 
 import android.app.usage.NetworkStatsManager;
@@ -92,9 +94,6 @@
         System.loadLibrary("tetherutilsjni");
     }
 
-    static final boolean DOWNSTREAM = true;
-    static final boolean UPSTREAM = false;
-
     private static final String TAG = BpfCoordinator.class.getSimpleName();
     private static final int DUMP_TIMEOUT_MS = 10_000;
     private static final MacAddress NULL_MAC_ADDRESS = MacAddress.fromString(
@@ -118,7 +117,6 @@
         return makeMapPath((downstream ? "downstream" : "upstream") + ipVersion);
     }
 
-
     @VisibleForTesting
     enum StatsType {
         STATS_PER_IFACE,
@@ -218,6 +216,9 @@
     // is okay for now because there have only one upstream generally.
     private final HashMap<Inet4Address, Integer> mIpv4UpstreamIndices = new HashMap<>();
 
+    // Map for upstream and downstream pair.
+    private final HashMap<String, HashSet<String>> mForwardingPairs = new HashMap<>();
+
     // Runnable that used by scheduling next polling of stats.
     private final Runnable mScheduledPollingTask = () -> {
         updateForwardedStats();
@@ -691,6 +692,37 @@
         }
     }
 
+    /**
+     * Attach BPF program
+     *
+     * TODO: consider error handling if the attach program failed.
+     */
+    public void maybeAttachProgram(@NonNull String intIface, @NonNull String extIface) {
+        if (forwardingPairExists(intIface, extIface)) return;
+
+        boolean firstDownstreamForThisUpstream = !isAnyForwardingPairOnUpstream(extIface);
+        forwardingPairAdd(intIface, extIface);
+
+        mBpfCoordinatorShim.attachProgram(intIface, UPSTREAM);
+        // Attach if the upstream is the first time to be used in a forwarding pair.
+        if (firstDownstreamForThisUpstream) {
+            mBpfCoordinatorShim.attachProgram(extIface, DOWNSTREAM);
+        }
+    }
+
+    /**
+     * Detach BPF program
+     */
+    public void maybeDetachProgram(@NonNull String intIface, @NonNull String extIface) {
+        forwardingPairRemove(intIface, extIface);
+
+        // Detaching program may fail because the interface has been removed already.
+        mBpfCoordinatorShim.detachProgram(intIface);
+        // Detach if no more forwarding pair is using the upstream.
+        if (!isAnyForwardingPairOnUpstream(extIface)) {
+            mBpfCoordinatorShim.detachProgram(extIface);
+        }
+    }
 
     // TODO: make mInterfaceNames accessible to the shim and move this code to there.
     private String getIfName(long ifindex) {
@@ -1227,6 +1259,33 @@
         return false;
     }
 
+    private void forwardingPairAdd(@NonNull String intIface, @NonNull String extIface) {
+        if (!mForwardingPairs.containsKey(extIface)) {
+            mForwardingPairs.put(extIface, new HashSet<String>());
+        }
+        mForwardingPairs.get(extIface).add(intIface);
+    }
+
+    private void forwardingPairRemove(@NonNull String intIface, @NonNull String extIface) {
+        HashSet<String> downstreams = mForwardingPairs.get(extIface);
+        if (downstreams == null) return;
+        if (!downstreams.remove(intIface)) return;
+
+        if (downstreams.isEmpty()) {
+            mForwardingPairs.remove(extIface);
+        }
+    }
+
+    private boolean forwardingPairExists(@NonNull String intIface, @NonNull String extIface) {
+        if (!mForwardingPairs.containsKey(extIface)) return false;
+
+        return mForwardingPairs.get(extIface).contains(intIface);
+    }
+
+    private boolean isAnyForwardingPairOnUpstream(@NonNull String extIface) {
+        return mForwardingPairs.containsKey(extIface);
+    }
+
     @NonNull
     private NetworkStats buildNetworkStats(@NonNull StatsType type, int ifIndex,
             @NonNull final ForwardedStats diff) {
diff --git a/Tethering/src/com/android/networkstack/tethering/BpfUtils.java b/Tethering/src/com/android/networkstack/tethering/BpfUtils.java
new file mode 100644
index 0000000..289452c
--- /dev/null
+++ b/Tethering/src/com/android/networkstack/tethering/BpfUtils.java
@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.networkstack.tethering;
+
+import static android.system.OsConstants.ETH_P_IP;
+import static android.system.OsConstants.ETH_P_IPV6;
+
+import android.net.util.InterfaceParams;
+
+import androidx.annotation.NonNull;
+
+import java.io.IOException;
+
+/**
+ * The classes and the methods for BPF utilization.
+ *
+ * {@hide}
+ */
+public class BpfUtils {
+    static {
+        System.loadLibrary("tetherutilsjni");
+    }
+
+    // For better code clarity when used for 'bool ingress' parameter.
+    static final boolean EGRESS = false;
+    static final boolean INGRESS = true;
+
+    // For better code clarify when used for 'bool downstream' parameter.
+    //
+    // This is talking about the direction of travel of the offloaded packets.
+    //
+    // Upstream means packets heading towards the internet/uplink (upload),
+    // thus for tethering this is attached to ingress on the downstream interface,
+    // while for clat this is attached to egress on the v4-* clat interface.
+    //
+    // Downstream means packets coming from the internet/uplink (download), thus
+    // for both clat and tethering this is attached to ingress on the upstream interface.
+    static final boolean DOWNSTREAM = true;
+    static final boolean UPSTREAM = false;
+
+    // The priority of clat/tether hooks - smaller is higher priority.
+    // TC tether is higher priority then TC clat to match XDP winning over TC.
+    // Sync from system/netd/server/OffloadUtils.h.
+    static final short PRIO_TETHER6 = 1;
+    static final short PRIO_TETHER4 = 2;
+    static final short PRIO_CLAT = 3;
+
+    private static String makeProgPath(boolean downstream, int ipVersion, boolean ether) {
+        String path = "/sys/fs/bpf/tethering/prog_offload_schedcls_tether_"
+                + (downstream ? "downstream" : "upstream")
+                + ipVersion + "_"
+                + (ether ? "ether" : "rawip");
+        return path;
+    }
+
+    /**
+     * Attach BPF program
+     *
+     * TODO: use interface index to replace interface name.
+     */
+    public static void attachProgram(@NonNull String iface, boolean downstream)
+            throws IOException {
+        final InterfaceParams params = InterfaceParams.getByName(iface);
+        if (params == null) {
+            throw new IOException("Fail to get interface params for interface " + iface);
+        }
+
+        boolean ether;
+        try {
+            ether = isEthernet(iface);
+        } catch (IOException e) {
+            throw new IOException("isEthernet(" + params.index + "[" + iface + "]) failure: " + e);
+        }
+
+        try {
+            // tc filter add dev .. ingress prio 1 protocol ipv6 bpf object-pinned /sys/fs/bpf/...
+            // direct-action
+            tcFilterAddDevBpf(params.index, INGRESS, PRIO_TETHER6, (short) ETH_P_IPV6,
+                    makeProgPath(downstream, 6, ether));
+        } catch (IOException e) {
+            throw new IOException("tc filter add dev (" + params.index + "[" + iface
+                    + "]) ingress prio PRIO_TETHER6 protocol ipv6 failure: " + e);
+        }
+
+        try {
+            // tc filter add dev .. ingress prio 2 protocol ip bpf object-pinned /sys/fs/bpf/...
+            // direct-action
+            tcFilterAddDevBpf(params.index, INGRESS, PRIO_TETHER4, (short) ETH_P_IP,
+                    makeProgPath(downstream, 4, ether));
+        } catch (IOException e) {
+            throw new IOException("tc filter add dev (" + params.index + "[" + iface
+                    + "]) ingress prio PRIO_TETHER4 protocol ip failure: " + e);
+        }
+    }
+
+    /**
+     * Detach BPF program
+     *
+     * TODO: use interface index to replace interface name.
+     */
+    public static void detachProgram(@NonNull String iface) throws IOException {
+        final InterfaceParams params = InterfaceParams.getByName(iface);
+        if (params == null) {
+            throw new IOException("Fail to get interface params for interface " + iface);
+        }
+
+        try {
+            // tc filter del dev .. ingress prio 1 protocol ipv6
+            tcFilterDelDev(params.index, INGRESS, PRIO_TETHER6, (short) ETH_P_IPV6);
+        } catch (IOException e) {
+            throw new IOException("tc filter del dev (" + params.index + "[" + iface
+                    + "]) ingress prio PRIO_TETHER6 protocol ipv6 failure: " + e);
+        }
+
+        try {
+            // tc filter del dev .. ingress prio 2 protocol ip
+            tcFilterDelDev(params.index, INGRESS, PRIO_TETHER4, (short) ETH_P_IP);
+        } catch (IOException e) {
+            throw new IOException("tc filter del dev (" + params.index + "[" + iface
+                    + "]) ingress prio PRIO_TETHER4 protocol ip failure: " + e);
+        }
+    }
+
+    private static native boolean isEthernet(String iface) throws IOException;
+
+    private static native void tcFilterAddDevBpf(int ifIndex, boolean ingress, short prio,
+            short proto, String bpfProgPath) throws IOException;
+
+    private static native void tcFilterDelDev(int ifIndex, boolean ingress, short prio,
+            short proto) throws IOException;
+}