diff --git a/packages/ConnectivityT/framework-t/Android.bp b/packages/ConnectivityT/framework-t/Android.bp
index 931a55b..0bda923 100644
--- a/packages/ConnectivityT/framework-t/Android.bp
+++ b/packages/ConnectivityT/framework-t/Android.bp
@@ -114,6 +114,23 @@
     ],
 }
 
+// Ethernet related libraries.
+
+filegroup {
+    name: "framework-connectivity-ethernet-sources",
+    srcs: [
+        "src/android/net/EthernetManager.java",
+        "src/android/net/EthernetNetworkSpecifier.java",
+        "src/android/net/IEthernetManager.aidl",
+        "src/android/net/IEthernetServiceListener.aidl",
+        "src/android/net/ITetheredInterfaceCallback.aidl",
+    ],
+    path: "src",
+    visibility: [
+        "//visibility:private",
+    ],
+}
+
 // Connectivity-T common libraries.
 
 filegroup {
@@ -130,6 +147,7 @@
 filegroup {
     name: "framework-connectivity-tiramisu-sources",
     srcs: [
+        ":framework-connectivity-ethernet-sources",
         ":framework-connectivity-ipsec-sources",
         ":framework-connectivity-netstats-sources",
         ":framework-connectivity-nsd-sources",
diff --git a/packages/ConnectivityT/framework-t/src/android/net/EthernetManager.java b/packages/ConnectivityT/framework-t/src/android/net/EthernetManager.java
new file mode 100644
index 0000000..7cd63ef
--- /dev/null
+++ b/packages/ConnectivityT/framework-t/src/android/net/EthernetManager.java
@@ -0,0 +1,318 @@
+/*
+ * Copyright (C) 2014 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 android.net;
+
+import android.annotation.NonNull;
+import android.annotation.RequiresPermission;
+import android.annotation.SystemApi;
+import android.annotation.SystemService;
+import android.annotation.TestApi;
+import android.compat.annotation.UnsupportedAppUsage;
+import android.content.Context;
+import android.os.Build;
+import android.os.RemoteException;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.os.BackgroundThread;
+
+import java.util.ArrayList;
+import java.util.Objects;
+import java.util.concurrent.Executor;
+
+/**
+ * A class representing the IP configuration of the Ethernet network.
+ *
+ * @hide
+ */
+@SystemApi
+@SystemService(Context.ETHERNET_SERVICE)
+public class EthernetManager {
+    private static final String TAG = "EthernetManager";
+
+    private final IEthernetManager mService;
+    @GuardedBy("mListeners")
+    private final ArrayList<ListenerInfo> mListeners = new ArrayList<>();
+    private final IEthernetServiceListener.Stub mServiceListener =
+            new IEthernetServiceListener.Stub() {
+                @Override
+                public void onAvailabilityChanged(String iface, boolean isAvailable) {
+                    synchronized (mListeners) {
+                        for (ListenerInfo li : mListeners) {
+                            li.executor.execute(() ->
+                                    li.listener.onAvailabilityChanged(iface, isAvailable));
+                        }
+                    }
+                }
+            };
+
+    private static class ListenerInfo {
+        @NonNull
+        public final Executor executor;
+        @NonNull
+        public final Listener listener;
+
+        private ListenerInfo(@NonNull Executor executor, @NonNull Listener listener) {
+            this.executor = executor;
+            this.listener = listener;
+        }
+    }
+
+    /**
+     * A listener interface to receive notification on changes in Ethernet.
+     * @hide
+     */
+    public interface Listener {
+        /**
+         * Called when Ethernet port's availability is changed.
+         * @param iface Ethernet interface name
+         * @param isAvailable {@code true} if Ethernet port exists.
+         * @hide
+         */
+        @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+        void onAvailabilityChanged(String iface, boolean isAvailable);
+    }
+
+    /**
+     * Create a new EthernetManager instance.
+     * Applications will almost always want to use
+     * {@link android.content.Context#getSystemService Context.getSystemService()} to retrieve
+     * the standard {@link android.content.Context#ETHERNET_SERVICE Context.ETHERNET_SERVICE}.
+     * @hide
+     */
+    public EthernetManager(Context context, IEthernetManager service) {
+        mService = service;
+    }
+
+    /**
+     * Get Ethernet configuration.
+     * @return the Ethernet Configuration, contained in {@link IpConfiguration}.
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public IpConfiguration getConfiguration(String iface) {
+        try {
+            return mService.getConfiguration(iface);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Set Ethernet configuration.
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public void setConfiguration(String iface, IpConfiguration config) {
+        try {
+            mService.setConfiguration(iface, config);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Indicates whether the system currently has one or more Ethernet interfaces.
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public boolean isAvailable() {
+        return getAvailableInterfaces().length > 0;
+    }
+
+    /**
+     * Indicates whether the system has given interface.
+     *
+     * @param iface Ethernet interface name
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public boolean isAvailable(String iface) {
+        try {
+            return mService.isAvailable(iface);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Adds a listener.
+     *
+     * Consider using {@link #addListener(Listener, Executor)} instead: this method uses a default
+     * executor that may have higher latency than a provided executor.
+     * @param listener A {@link Listener} to add.
+     * @throws IllegalArgumentException If the listener is null.
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public void addListener(@NonNull Listener listener) {
+        addListener(listener, BackgroundThread.getExecutor());
+    }
+
+    /**
+     * Adds a listener.
+     * @param listener A {@link Listener} to add.
+     * @param executor Executor to run callbacks on.
+     * @throws IllegalArgumentException If the listener or executor is null.
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public void addListener(@NonNull Listener listener, @NonNull Executor executor) {
+        if (listener == null || executor == null) {
+            throw new NullPointerException("listener and executor must not be null");
+        }
+        synchronized (mListeners) {
+            mListeners.add(new ListenerInfo(executor, listener));
+            if (mListeners.size() == 1) {
+                try {
+                    mService.addListener(mServiceListener);
+                } catch (RemoteException e) {
+                    throw e.rethrowFromSystemServer();
+                }
+            }
+        }
+    }
+
+    /**
+     * Returns an array of available Ethernet interface names.
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public String[] getAvailableInterfaces() {
+        try {
+            return mService.getAvailableInterfaces();
+        } catch (RemoteException e) {
+            throw e.rethrowAsRuntimeException();
+        }
+    }
+
+    /**
+     * Removes a listener.
+     * @param listener A {@link Listener} to remove.
+     * @throws IllegalArgumentException If the listener is null.
+     * @hide
+     */
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
+    public void removeListener(@NonNull Listener listener) {
+        if (listener == null) {
+            throw new IllegalArgumentException("listener must not be null");
+        }
+        synchronized (mListeners) {
+            mListeners.removeIf(l -> l.listener == listener);
+            if (mListeners.isEmpty()) {
+                try {
+                    mService.removeListener(mServiceListener);
+                } catch (RemoteException e) {
+                    throw e.rethrowFromSystemServer();
+                }
+            }
+        }
+    }
+
+    /**
+     * Whether to treat interfaces created by {@link TestNetworkManager#createTapInterface}
+     * as Ethernet interfaces. The effects of this method apply to any test interfaces that are
+     * already present on the system.
+     * @hide
+     */
+    @TestApi
+    public void setIncludeTestInterfaces(boolean include) {
+        try {
+            mService.setIncludeTestInterfaces(include);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * A request for a tethered interface.
+     */
+    public static class TetheredInterfaceRequest {
+        private final IEthernetManager mService;
+        private final ITetheredInterfaceCallback mCb;
+
+        private TetheredInterfaceRequest(@NonNull IEthernetManager service,
+                @NonNull ITetheredInterfaceCallback cb) {
+            this.mService = service;
+            this.mCb = cb;
+        }
+
+        /**
+         * Release the request, causing the interface to revert back from tethering mode if there
+         * is no other requestor.
+         */
+        public void release() {
+            try {
+                mService.releaseTetheredInterface(mCb);
+            } catch (RemoteException e) {
+                e.rethrowFromSystemServer();
+            }
+        }
+    }
+
+    /**
+     * Callback for {@link #requestTetheredInterface(TetheredInterfaceCallback)}.
+     */
+    public interface TetheredInterfaceCallback {
+        /**
+         * Called when the tethered interface is available.
+         * @param iface The name of the interface.
+         */
+        void onAvailable(@NonNull String iface);
+
+        /**
+         * Called when the tethered interface is now unavailable.
+         */
+        void onUnavailable();
+    }
+
+    /**
+     * Request a tethered interface in tethering mode.
+     *
+     * <p>When this method is called and there is at least one ethernet interface available, the
+     * system will designate one to act as a tethered interface. If there is already a tethered
+     * interface, the existing interface will be used.
+     * @param callback A callback to be called once the request has been fulfilled.
+     */
+    @RequiresPermission(anyOf = {
+            android.Manifest.permission.NETWORK_STACK,
+            android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK
+    })
+    @NonNull
+    public TetheredInterfaceRequest requestTetheredInterface(@NonNull final Executor executor,
+            @NonNull final TetheredInterfaceCallback callback) {
+        Objects.requireNonNull(callback, "Callback must be non-null");
+        Objects.requireNonNull(executor, "Executor must be non-null");
+        final ITetheredInterfaceCallback cbInternal = new ITetheredInterfaceCallback.Stub() {
+            @Override
+            public void onAvailable(String iface) {
+                executor.execute(() -> callback.onAvailable(iface));
+            }
+
+            @Override
+            public void onUnavailable() {
+                executor.execute(() -> callback.onUnavailable());
+            }
+        };
+
+        try {
+            mService.requestTetheredInterface(cbInternal);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+        return new TetheredInterfaceRequest(mService, cbInternal);
+    }
+}
diff --git a/packages/ConnectivityT/framework-t/src/android/net/EthernetNetworkSpecifier.java b/packages/ConnectivityT/framework-t/src/android/net/EthernetNetworkSpecifier.java
new file mode 100644
index 0000000..62c5761
--- /dev/null
+++ b/packages/ConnectivityT/framework-t/src/android/net/EthernetNetworkSpecifier.java
@@ -0,0 +1,104 @@
+/*
+ * 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 android.net;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.SystemApi;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.text.TextUtils;
+
+import com.android.internal.util.Preconditions;
+
+import java.util.Objects;
+
+/**
+ * A {@link NetworkSpecifier} used to identify ethernet interfaces.
+ *
+ * @see EthernetManager
+ * @hide
+ */
+@SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+public final class EthernetNetworkSpecifier extends NetworkSpecifier implements Parcelable {
+
+    /**
+     * Name of the network interface.
+     */
+    @NonNull
+    private final String mInterfaceName;
+
+    /**
+     * Create a new EthernetNetworkSpecifier.
+     * @param interfaceName Name of the ethernet interface the specifier refers to.
+     */
+    public EthernetNetworkSpecifier(@NonNull String interfaceName) {
+        Preconditions.checkStringNotEmpty(interfaceName);
+        mInterfaceName = interfaceName;
+    }
+
+    /**
+     * Get the name of the ethernet interface the specifier refers to.
+     */
+    @Nullable
+    public String getInterfaceName() {
+        // This may be null in the future to support specifiers based on data other than the
+        // interface name.
+        return mInterfaceName;
+    }
+
+    @Override
+    public boolean canBeSatisfiedBy(@Nullable NetworkSpecifier other) {
+        return equals(other);
+    }
+
+    @Override
+    public boolean equals(@Nullable Object o) {
+        if (!(o instanceof EthernetNetworkSpecifier)) return false;
+        return TextUtils.equals(mInterfaceName, ((EthernetNetworkSpecifier) o).mInterfaceName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(mInterfaceName);
+    }
+
+    @Override
+    public String toString() {
+        return "EthernetNetworkSpecifier (" + mInterfaceName + ")";
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        dest.writeString(mInterfaceName);
+    }
+
+    public static final @NonNull Parcelable.Creator<EthernetNetworkSpecifier> CREATOR =
+            new Parcelable.Creator<EthernetNetworkSpecifier>() {
+        public EthernetNetworkSpecifier createFromParcel(Parcel in) {
+            return new EthernetNetworkSpecifier(in.readString());
+        }
+        public EthernetNetworkSpecifier[] newArray(int size) {
+            return new EthernetNetworkSpecifier[size];
+        }
+    };
+}
diff --git a/packages/ConnectivityT/framework-t/src/android/net/IEthernetManager.aidl b/packages/ConnectivityT/framework-t/src/android/net/IEthernetManager.aidl
new file mode 100644
index 0000000..e058e5a
--- /dev/null
+++ b/packages/ConnectivityT/framework-t/src/android/net/IEthernetManager.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2014 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 android.net;
+
+import android.net.IpConfiguration;
+import android.net.IEthernetServiceListener;
+import android.net.ITetheredInterfaceCallback;
+
+/**
+ * Interface that answers queries about, and allows changing
+ * ethernet configuration.
+ */
+/** {@hide} */
+interface IEthernetManager
+{
+    String[] getAvailableInterfaces();
+    IpConfiguration getConfiguration(String iface);
+    void setConfiguration(String iface, in IpConfiguration config);
+    boolean isAvailable(String iface);
+    void addListener(in IEthernetServiceListener listener);
+    void removeListener(in IEthernetServiceListener listener);
+    void setIncludeTestInterfaces(boolean include);
+    void requestTetheredInterface(in ITetheredInterfaceCallback callback);
+    void releaseTetheredInterface(in ITetheredInterfaceCallback callback);
+}
diff --git a/packages/ConnectivityT/framework-t/src/android/net/IEthernetServiceListener.aidl b/packages/ConnectivityT/framework-t/src/android/net/IEthernetServiceListener.aidl
new file mode 100644
index 0000000..782fa19
--- /dev/null
+++ b/packages/ConnectivityT/framework-t/src/android/net/IEthernetServiceListener.aidl
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2014 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 android.net;
+
+/** @hide */
+oneway interface IEthernetServiceListener
+{
+    void onAvailabilityChanged(String iface, boolean isAvailable);
+}
diff --git a/packages/ConnectivityT/framework-t/src/android/net/ITetheredInterfaceCallback.aidl b/packages/ConnectivityT/framework-t/src/android/net/ITetheredInterfaceCallback.aidl
new file mode 100644
index 0000000..14aa023
--- /dev/null
+++ b/packages/ConnectivityT/framework-t/src/android/net/ITetheredInterfaceCallback.aidl
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2020 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 android.net;
+
+/** @hide */
+oneway interface ITetheredInterfaceCallback {
+    void onAvailable(in String iface);
+    void onUnavailable();
+}
\ No newline at end of file
diff --git a/packages/ConnectivityT/service/Android.bp b/packages/ConnectivityT/service/Android.bp
index 7b88176..97dfb64 100644
--- a/packages/ConnectivityT/service/Android.bp
+++ b/packages/ConnectivityT/service/Android.bp
@@ -61,11 +61,25 @@
     ],
 }
 
+// Ethernet related libraries.
+
+filegroup {
+    name: "services.connectivity-ethernet-sources",
+    srcs: [
+        "src/com/android/server/net/IpConfigStore.java",
+    ],
+    path: "src",
+    visibility: [
+        "//frameworks/opt/net/ethernet",
+    ],
+}
+
 // Connectivity-T common libraries.
 
 filegroup {
     name: "services.connectivity-tiramisu-sources",
     srcs: [
+        ":services.connectivity-ethernet-sources",
         ":services.connectivity-ipsec-sources",
         ":services.connectivity-netstats-sources",
         ":services.connectivity-nsd-sources",
diff --git a/packages/ConnectivityT/service/src/com/android/server/net/IpConfigStore.java b/packages/ConnectivityT/service/src/com/android/server/net/IpConfigStore.java
new file mode 100644
index 0000000..3a9a544
--- /dev/null
+++ b/packages/ConnectivityT/service/src/com/android/server/net/IpConfigStore.java
@@ -0,0 +1,449 @@
+/*
+ * Copyright (C) 2014 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.server.net;
+
+import android.net.InetAddresses;
+import android.net.IpConfiguration;
+import android.net.IpConfiguration.IpAssignment;
+import android.net.IpConfiguration.ProxySettings;
+import android.net.LinkAddress;
+import android.net.ProxyInfo;
+import android.net.StaticIpConfiguration;
+import android.net.Uri;
+import android.util.ArrayMap;
+import android.util.Log;
+import android.util.SparseArray;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.net.module.util.ProxyUtils;
+
+import java.io.BufferedInputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.EOFException;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * This class provides an API to store and manage L3 network IP configuration.
+ */
+public class IpConfigStore {
+    private static final String TAG = "IpConfigStore";
+    private static final boolean DBG = false;
+
+    protected final DelayedDiskWrite mWriter;
+
+    /* IP and proxy configuration keys */
+    protected static final String ID_KEY = "id";
+    protected static final String IP_ASSIGNMENT_KEY = "ipAssignment";
+    protected static final String LINK_ADDRESS_KEY = "linkAddress";
+    protected static final String GATEWAY_KEY = "gateway";
+    protected static final String DNS_KEY = "dns";
+    protected static final String PROXY_SETTINGS_KEY = "proxySettings";
+    protected static final String PROXY_HOST_KEY = "proxyHost";
+    protected static final String PROXY_PORT_KEY = "proxyPort";
+    protected static final String PROXY_PAC_FILE = "proxyPac";
+    protected static final String EXCLUSION_LIST_KEY = "exclusionList";
+    protected static final String EOS = "eos";
+
+    protected static final int IPCONFIG_FILE_VERSION = 3;
+
+    public IpConfigStore(DelayedDiskWrite writer) {
+        mWriter = writer;
+    }
+
+    public IpConfigStore() {
+        this(new DelayedDiskWrite());
+    }
+
+    private static boolean writeConfig(DataOutputStream out, String configKey,
+            IpConfiguration config) throws IOException {
+        return writeConfig(out, configKey, config, IPCONFIG_FILE_VERSION);
+    }
+
+    /**
+     *  Write the IP configuration with the given parameters to {@link DataOutputStream}.
+     */
+    @VisibleForTesting
+    public static boolean writeConfig(DataOutputStream out, String configKey,
+                                IpConfiguration config, int version) throws IOException {
+        boolean written = false;
+
+        try {
+            switch (config.getIpAssignment()) {
+                case STATIC:
+                    out.writeUTF(IP_ASSIGNMENT_KEY);
+                    out.writeUTF(config.getIpAssignment().toString());
+                    StaticIpConfiguration staticIpConfiguration = config.getStaticIpConfiguration();
+                    if (staticIpConfiguration != null) {
+                        if (staticIpConfiguration.getIpAddress() != null) {
+                            LinkAddress ipAddress = staticIpConfiguration.getIpAddress();
+                            out.writeUTF(LINK_ADDRESS_KEY);
+                            out.writeUTF(ipAddress.getAddress().getHostAddress());
+                            out.writeInt(ipAddress.getPrefixLength());
+                        }
+                        if (staticIpConfiguration.getGateway() != null) {
+                            out.writeUTF(GATEWAY_KEY);
+                            out.writeInt(0);  // Default route.
+                            out.writeInt(1);  // Have a gateway.
+                            out.writeUTF(staticIpConfiguration.getGateway().getHostAddress());
+                        }
+                        for (InetAddress inetAddr : staticIpConfiguration.getDnsServers()) {
+                            out.writeUTF(DNS_KEY);
+                            out.writeUTF(inetAddr.getHostAddress());
+                        }
+                    }
+                    written = true;
+                    break;
+                case DHCP:
+                    out.writeUTF(IP_ASSIGNMENT_KEY);
+                    out.writeUTF(config.getIpAssignment().toString());
+                    written = true;
+                    break;
+                case UNASSIGNED:
+                /* Ignore */
+                    break;
+                default:
+                    loge("Ignore invalid ip assignment while writing");
+                    break;
+            }
+
+            switch (config.getProxySettings()) {
+                case STATIC:
+                    ProxyInfo proxyProperties = config.getHttpProxy();
+                    String exclusionList = ProxyUtils.exclusionListAsString(
+                            proxyProperties.getExclusionList());
+                    out.writeUTF(PROXY_SETTINGS_KEY);
+                    out.writeUTF(config.getProxySettings().toString());
+                    out.writeUTF(PROXY_HOST_KEY);
+                    out.writeUTF(proxyProperties.getHost());
+                    out.writeUTF(PROXY_PORT_KEY);
+                    out.writeInt(proxyProperties.getPort());
+                    if (exclusionList != null) {
+                        out.writeUTF(EXCLUSION_LIST_KEY);
+                        out.writeUTF(exclusionList);
+                    }
+                    written = true;
+                    break;
+                case PAC:
+                    ProxyInfo proxyPacProperties = config.getHttpProxy();
+                    out.writeUTF(PROXY_SETTINGS_KEY);
+                    out.writeUTF(config.getProxySettings().toString());
+                    out.writeUTF(PROXY_PAC_FILE);
+                    out.writeUTF(proxyPacProperties.getPacFileUrl().toString());
+                    written = true;
+                    break;
+                case NONE:
+                    out.writeUTF(PROXY_SETTINGS_KEY);
+                    out.writeUTF(config.getProxySettings().toString());
+                    written = true;
+                    break;
+                case UNASSIGNED:
+                    /* Ignore */
+                    break;
+                default:
+                    loge("Ignore invalid proxy settings while writing");
+                    break;
+            }
+
+            if (written) {
+                out.writeUTF(ID_KEY);
+                if (version < 3) {
+                    out.writeInt(Integer.valueOf(configKey));
+                } else {
+                    out.writeUTF(configKey);
+                }
+            }
+        } catch (NullPointerException e) {
+            loge("Failure in writing " + config + e);
+        }
+        out.writeUTF(EOS);
+
+        return written;
+    }
+
+    /**
+     * @deprecated use {@link #writeIpConfigurations(String, ArrayMap)} instead.
+     * New method uses string as network identifier which could be interface name or MAC address or
+     * other token.
+     */
+    @Deprecated
+    public void writeIpAndProxyConfigurationsToFile(String filePath,
+                                              final SparseArray<IpConfiguration> networks) {
+        mWriter.write(filePath, out -> {
+            out.writeInt(IPCONFIG_FILE_VERSION);
+            for (int i = 0; i < networks.size(); i++) {
+                writeConfig(out, String.valueOf(networks.keyAt(i)), networks.valueAt(i));
+            }
+        });
+    }
+
+    /**
+     *  Write the IP configuration associated to the target networks to the destination path.
+     */
+    public void writeIpConfigurations(String filePath,
+                                      ArrayMap<String, IpConfiguration> networks) {
+        mWriter.write(filePath, out -> {
+            out.writeInt(IPCONFIG_FILE_VERSION);
+            for (int i = 0; i < networks.size(); i++) {
+                writeConfig(out, networks.keyAt(i), networks.valueAt(i));
+            }
+        });
+    }
+
+    /**
+     * Read the IP configuration from the destination path to {@link BufferedInputStream}.
+     */
+    public static ArrayMap<String, IpConfiguration> readIpConfigurations(String filePath) {
+        BufferedInputStream bufferedInputStream;
+        try {
+            bufferedInputStream = new BufferedInputStream(new FileInputStream(filePath));
+        } catch (FileNotFoundException e) {
+            // Return an empty array here because callers expect an empty array when the file is
+            // not present.
+            loge("Error opening configuration file: " + e);
+            return new ArrayMap<>(0);
+        }
+        return readIpConfigurations(bufferedInputStream);
+    }
+
+    /** @deprecated use {@link #readIpConfigurations(String)} */
+    @Deprecated
+    public static SparseArray<IpConfiguration> readIpAndProxyConfigurations(String filePath) {
+        BufferedInputStream bufferedInputStream;
+        try {
+            bufferedInputStream = new BufferedInputStream(new FileInputStream(filePath));
+        } catch (FileNotFoundException e) {
+            // Return an empty array here because callers expect an empty array when the file is
+            // not present.
+            loge("Error opening configuration file: " + e);
+            return new SparseArray<>();
+        }
+        return readIpAndProxyConfigurations(bufferedInputStream);
+    }
+
+    /** @deprecated use {@link #readIpConfigurations(InputStream)} */
+    @Deprecated
+    public static SparseArray<IpConfiguration> readIpAndProxyConfigurations(
+            InputStream inputStream) {
+        ArrayMap<String, IpConfiguration> networks = readIpConfigurations(inputStream);
+        if (networks == null) {
+            return null;
+        }
+
+        SparseArray<IpConfiguration> networksById = new SparseArray<>();
+        for (int i = 0; i < networks.size(); i++) {
+            int id = Integer.valueOf(networks.keyAt(i));
+            networksById.put(id, networks.valueAt(i));
+        }
+
+        return networksById;
+    }
+
+    /** Returns a map of network identity token and {@link IpConfiguration}. */
+    public static ArrayMap<String, IpConfiguration> readIpConfigurations(
+            InputStream inputStream) {
+        ArrayMap<String, IpConfiguration> networks = new ArrayMap<>();
+        DataInputStream in = null;
+        try {
+            in = new DataInputStream(inputStream);
+
+            int version = in.readInt();
+            if (version != 3 && version != 2 && version != 1) {
+                loge("Bad version on IP configuration file, ignore read");
+                return null;
+            }
+
+            while (true) {
+                String uniqueToken = null;
+                // Default is DHCP with no proxy
+                IpAssignment ipAssignment = IpAssignment.DHCP;
+                ProxySettings proxySettings = ProxySettings.NONE;
+                StaticIpConfiguration staticIpConfiguration = new StaticIpConfiguration();
+                LinkAddress linkAddress = null;
+                InetAddress gatewayAddress = null;
+                String proxyHost = null;
+                String pacFileUrl = null;
+                int proxyPort = -1;
+                String exclusionList = null;
+                String key;
+                final List<InetAddress> dnsServers = new ArrayList<>();
+
+                do {
+                    key = in.readUTF();
+                    try {
+                        if (key.equals(ID_KEY)) {
+                            if (version < 3) {
+                                int id = in.readInt();
+                                uniqueToken = String.valueOf(id);
+                            } else {
+                                uniqueToken = in.readUTF();
+                            }
+                        } else if (key.equals(IP_ASSIGNMENT_KEY)) {
+                            ipAssignment = IpAssignment.valueOf(in.readUTF());
+                        } else if (key.equals(LINK_ADDRESS_KEY)) {
+                            LinkAddress parsedLinkAddress =
+                                    new LinkAddress(
+                                            InetAddresses.parseNumericAddress(in.readUTF()),
+                                            in.readInt());
+                            if (parsedLinkAddress.getAddress() instanceof Inet4Address
+                                    && linkAddress == null) {
+                                linkAddress = parsedLinkAddress;
+                            } else {
+                                loge("Non-IPv4 or duplicate address: " + parsedLinkAddress);
+                            }
+                        } else if (key.equals(GATEWAY_KEY)) {
+                            LinkAddress dest = null;
+                            InetAddress gateway = null;
+                            if (version == 1) {
+                                // only supported default gateways - leave the dest/prefix empty
+                                gateway = InetAddresses.parseNumericAddress(in.readUTF());
+                                if (gatewayAddress == null) {
+                                    gatewayAddress = gateway;
+                                } else {
+                                    loge("Duplicate gateway: " + gateway.getHostAddress());
+                                }
+                            } else {
+                                if (in.readInt() == 1) {
+                                    dest =
+                                            new LinkAddress(
+                                                    InetAddresses.parseNumericAddress(in.readUTF()),
+                                                    in.readInt());
+                                }
+                                if (in.readInt() == 1) {
+                                    gateway = InetAddresses.parseNumericAddress(in.readUTF());
+                                }
+                                // If the destination is a default IPv4 route, use the gateway
+                                // address unless already set. If there is no destination, assume
+                                // it is default route and use the gateway address in all cases.
+                                if (dest == null) {
+                                    gatewayAddress = gateway;
+                                } else if (dest.getAddress() instanceof Inet4Address
+                                        && dest.getPrefixLength() == 0 && gatewayAddress == null) {
+                                    gatewayAddress = gateway;
+                                } else {
+                                    loge("Non-IPv4 default or duplicate route: "
+                                            + dest.getAddress());
+                                }
+                            }
+                        } else if (key.equals(DNS_KEY)) {
+                            dnsServers.add(InetAddresses.parseNumericAddress(in.readUTF()));
+                        } else if (key.equals(PROXY_SETTINGS_KEY)) {
+                            proxySettings = ProxySettings.valueOf(in.readUTF());
+                        } else if (key.equals(PROXY_HOST_KEY)) {
+                            proxyHost = in.readUTF();
+                        } else if (key.equals(PROXY_PORT_KEY)) {
+                            proxyPort = in.readInt();
+                        } else if (key.equals(PROXY_PAC_FILE)) {
+                            pacFileUrl = in.readUTF();
+                        } else if (key.equals(EXCLUSION_LIST_KEY)) {
+                            exclusionList = in.readUTF();
+                        } else if (key.equals(EOS)) {
+                            break;
+                        } else {
+                            loge("Ignore unknown key " + key + "while reading");
+                        }
+                    } catch (IllegalArgumentException e) {
+                        loge("Ignore invalid address while reading" + e);
+                    }
+                } while (true);
+
+                staticIpConfiguration = new StaticIpConfiguration.Builder()
+                    .setIpAddress(linkAddress)
+                    .setGateway(gatewayAddress)
+                    .setDnsServers(dnsServers)
+                    .build();
+
+                if (uniqueToken != null) {
+                    IpConfiguration config = new IpConfiguration();
+                    networks.put(uniqueToken, config);
+
+                    switch (ipAssignment) {
+                        case STATIC:
+                            config.setStaticIpConfiguration(staticIpConfiguration);
+                            config.setIpAssignment(ipAssignment);
+                            break;
+                        case DHCP:
+                            config.setIpAssignment(ipAssignment);
+                            break;
+                        case UNASSIGNED:
+                            loge("BUG: Found UNASSIGNED IP on file, use DHCP");
+                            config.setIpAssignment(IpAssignment.DHCP);
+                            break;
+                        default:
+                            loge("Ignore invalid ip assignment while reading.");
+                            config.setIpAssignment(IpAssignment.UNASSIGNED);
+                            break;
+                    }
+
+                    switch (proxySettings) {
+                        case STATIC:
+                            ProxyInfo proxyInfo = ProxyInfo.buildDirectProxy(proxyHost, proxyPort,
+                                    ProxyUtils.exclusionStringAsList(exclusionList));
+                            config.setProxySettings(proxySettings);
+                            config.setHttpProxy(proxyInfo);
+                            break;
+                        case PAC:
+                            ProxyInfo proxyPacProperties =
+                                    ProxyInfo.buildPacProxy(Uri.parse(pacFileUrl));
+                            config.setProxySettings(proxySettings);
+                            config.setHttpProxy(proxyPacProperties);
+                            break;
+                        case NONE:
+                            config.setProxySettings(proxySettings);
+                            break;
+                        case UNASSIGNED:
+                            loge("BUG: Found UNASSIGNED proxy on file, use NONE");
+                            config.setProxySettings(ProxySettings.NONE);
+                            break;
+                        default:
+                            loge("Ignore invalid proxy settings while reading");
+                            config.setProxySettings(ProxySettings.UNASSIGNED);
+                            break;
+                    }
+                } else {
+                    if (DBG) log("Missing id while parsing configuration");
+                }
+            }
+        } catch (EOFException ignore) {
+        } catch (IOException e) {
+            loge("Error parsing configuration: " + e);
+        } finally {
+            if (in != null) {
+                try {
+                    in.close();
+                } catch (Exception e) { }
+            }
+        }
+
+        return networks;
+    }
+
+    protected static void loge(String s) {
+        Log.e(TAG, s);
+    }
+
+    protected static void log(String s) {
+        Log.d(TAG, s);
+    }
+}