diff --git a/wifi/netlinkinterceptor/aidl/default/Android.bp b/wifi/netlinkinterceptor/aidl/default/Android.bp
new file mode 100644
index 0000000..686ff19
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/Android.bp
@@ -0,0 +1,39 @@
+//
+// 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.
+//
+
+cc_binary {
+    name: "android.hardware.net.nlinterceptor-service.default",
+    init_rc: ["nlinterceptor-default.rc"],
+    vintf_fragments: ["nlinterceptor-default.xml"],
+    vendor: true,
+    relative_install_path: "hw",
+    defaults: ["nlinterceptor@defaults"],
+    shared_libs: [
+        "android.hardware.net.nlinterceptor-V1-ndk",
+        "libbase",
+        "libbinder_ndk",
+    ],
+    static_libs: [
+        "libnlinterceptor",
+        "libnl++",
+    ],
+    srcs: [
+        "InterceptorRelay.cpp",
+        "NetlinkInterceptor.cpp",
+        "service.cpp",
+        "util.cpp",
+    ],
+}
diff --git a/wifi/netlinkinterceptor/aidl/default/InterceptorRelay.cpp b/wifi/netlinkinterceptor/aidl/default/InterceptorRelay.cpp
new file mode 100644
index 0000000..ded9122
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/InterceptorRelay.cpp
@@ -0,0 +1,129 @@
+/*
+ * 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.
+ */
+
+#include "InterceptorRelay.h"
+
+#include <android-base/logging.h>
+#include <libnl++/printer.h>
+#include <poll.h>
+
+#include <chrono>
+
+#include "util.h"
+
+namespace android::nlinterceptor {
+using namespace std::chrono_literals;
+
+static constexpr std::chrono::milliseconds kPollTimeout = 300ms;
+static constexpr bool kSuperVerbose = true;
+
+InterceptorRelay::InterceptorRelay(uint32_t nlFamily, uint32_t clientNlPid,
+                                   const std::string& clientName)
+    : mClientName(clientName),
+      mNlSocket(std::make_optional<nl::Socket>(nlFamily, 0, 0)),
+      mClientNlPid(clientNlPid) {}
+
+InterceptorRelay::~InterceptorRelay() {
+    mRunning = false;
+    if (mRelayThread.joinable()) mRelayThread.join();
+}
+
+uint32_t InterceptorRelay::getPid() {
+    auto pidMaybe = mNlSocket->getPid();
+    CHECK(pidMaybe.has_value()) << "Failed to get pid of nl::Socket!";
+    return *pidMaybe;
+}
+
+void InterceptorRelay::relayMessages() {
+    pollfd fds[] = {
+        mNlSocket->preparePoll(POLLIN),
+    };
+    while (mRunning) {
+        if (poll(fds, countof(fds), kPollTimeout.count()) < 0) {
+            PLOG(FATAL) << "poll failed";
+            return;
+        }
+        const auto nlsockEvents = fds[0].revents;
+
+        if (isSocketBad(nlsockEvents)) {
+            LOG(ERROR) << "Netlink socket is bad";
+            mRunning = false;
+            return;
+        }
+        if (!isSocketReadable(nlsockEvents)) continue;
+
+        const auto [msgMaybe, sa] = mNlSocket->receiveFrom();
+        if (!msgMaybe.has_value()) {
+            LOG(ERROR) << "Failed to receive Netlink data!";
+            mRunning = false;
+            return;
+        }
+        const auto msg = *msgMaybe;
+        if (!msg.firstOk()) {
+            LOG(ERROR) << "Netlink packet is malformed!";
+            // Test messages might be empty, this isn't fatal.
+            continue;
+        }
+        if constexpr (kSuperVerbose) {
+            LOG(VERBOSE) << "[" << mClientName
+                         << "] nlMsg: " << nl::toString(msg, NETLINK_GENERIC);
+        }
+
+        uint32_t destinationPid = 0;
+        if (sa.nl_pid == 0) {
+            destinationPid = mClientNlPid;
+        }
+
+        if (!mNlSocket->send(msg, destinationPid)) {
+            LOG(ERROR) << "Failed to send Netlink message!";
+            mRunning = false;
+            return;
+        }
+    }
+    LOG(VERBOSE) << "[" << mClientName << "] Exiting relay thread!";
+}
+
+bool InterceptorRelay::start() {
+    if (mRunning) {
+        LOG(ERROR)
+            << "Can't relay messages: InterceptorRelay is already running!";
+        return false;
+    }
+    if (mRelayThread.joinable()) {
+        LOG(ERROR) << "relay thread is already running!";
+        return false;
+    }
+    if (!mNlSocket.has_value()) {
+        LOG(ERROR) << "Netlink socket not initialized!";
+        return false;
+    }
+
+    mRunning = true;
+    mRelayThread = std::thread(&InterceptorRelay::relayMessages, this);
+
+    LOG(VERBOSE) << "Relay threads initialized";
+    return true;
+}
+
+bool InterceptorRelay::subscribeGroup(uint32_t nlGroup) {
+    return mNlSocket->addMembership(nlGroup);
+}
+
+bool InterceptorRelay::unsubscribeGroup(uint32_t nlGroup) {
+    return mNlSocket->dropMembership(nlGroup);
+}
+
+}  // namespace android::nlinterceptor
diff --git a/wifi/netlinkinterceptor/aidl/default/InterceptorRelay.h b/wifi/netlinkinterceptor/aidl/default/InterceptorRelay.h
new file mode 100644
index 0000000..0178c90
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/InterceptorRelay.h
@@ -0,0 +1,93 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <libnl++/Socket.h>
+
+#include <mutex>
+#include <thread>
+
+namespace android::nlinterceptor {
+
+class InterceptorRelay {
+   public:
+    /**
+     * Wrapper around the netlink socket and thread which relays messages.
+     *
+     * \param nlFamily - netlink family to use for the netlink socket.
+     * \param clientNlPid - pid of the client netlink socket.
+     * \param clientName - name of the client to be used for debugging.
+     */
+    InterceptorRelay(uint32_t nlFamily, uint32_t clientNlPid,
+                     const std::string& clientName);
+
+    /**
+     * Stops the relay thread if running and destroys itself.
+     */
+    ~InterceptorRelay();
+
+    /**
+     * Returns the PID of the internal Netlink socket.
+     *
+     * \return value of PID,
+     */
+    uint32_t getPid();
+
+    /**
+     * Spawns relay thread.
+     */
+    bool start();
+
+    /**
+     * Subscribes the internal socket to a single Netlink multicast group.
+     *
+     * \param nlGroup - Netlink group to subscribe to.
+     * \returns - true for success, false for failure.
+     */
+    bool subscribeGroup(uint32_t nlGroup);
+
+    /**
+     * Unsubscribes the internal socket from a single Netlink multicast group.
+     *
+     * \param nlGroup - Netlink group to unsubscribe from.
+     * \returns - true for success, false for failure.
+     */
+    bool unsubscribeGroup(uint32_t nlGroup);
+
+   private:
+    std::string mClientName;  ///< Name of client (Wificond, for example).
+    std::optional<nl::Socket> mNlSocket;
+    const uint32_t mClientNlPid = 0;  ///< pid of client NL socket.
+
+    /**
+     * If set to true, the relay thread should be running. Setting this to false
+     * stops the relay thread.
+     */
+    std::atomic_bool mRunning = false;
+
+    /**
+     * Reads incoming Netlink messages destined for mNlSocket. If from the
+     * kernel, the message is relayed to the client specified in the
+     * constructor. Otherwise, the message is relayed to the kernel. This will
+     * run as long as mRunning is set to true.
+     */
+    void relayMessages();
+
+    std::thread mRelayThread;
+};
+
+}  // namespace android::nlinterceptor
diff --git a/wifi/netlinkinterceptor/aidl/default/NetlinkInterceptor.cpp b/wifi/netlinkinterceptor/aidl/default/NetlinkInterceptor.cpp
new file mode 100644
index 0000000..908ecf2
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/NetlinkInterceptor.cpp
@@ -0,0 +1,121 @@
+/*
+ * 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.
+ */
+
+#include "NetlinkInterceptor.h"
+
+#include <android-base/logging.h>
+#include <libnl++/Socket.h>
+
+namespace android::nlinterceptor {
+
+ndk::ScopedAStatus NetlinkInterceptor::createSocket(
+    int32_t nlFamilyAidl, int32_t clientNlPidAidl,
+    const std::string& clientName, AidlInterceptedSocket* interceptedSocket) {
+    auto nlFamily = static_cast<uint32_t>(nlFamilyAidl);
+    auto clientNlPid = static_cast<uint32_t>(clientNlPidAidl);
+    uint32_t interceptorNlPid = 0;
+
+    std::unique_ptr<InterceptorRelay> interceptor =
+        std::make_unique<InterceptorRelay>(nlFamily, clientNlPid, clientName);
+
+    interceptorNlPid = interceptor->getPid();
+
+    if (interceptorNlPid == 0) {
+        LOG(ERROR) << "Failed to create a Netlink socket for " << clientName
+                   << ", " << nlFamily << ":" << clientNlPid;
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+
+    if (mClientMap.find({nlFamily, interceptorNlPid}) != mClientMap.end()) {
+        LOG(ERROR) << "A socket with pid " << interceptorNlPid
+                   << " already exists!";
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+
+    if (!interceptor->start()) {
+        LOG(ERROR) << "Failed to start interceptor thread!";
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+
+    if (!mClientMap
+             .emplace(InterceptedSocket(nlFamily, interceptorNlPid),
+                      std::move(interceptor))
+             .second) {
+        // If this happens, it is very bad.
+        LOG(FATAL) << "Failed to insert interceptor instance with pid "
+                   << interceptorNlPid << " into map!";
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+
+    interceptedSocket->nlFamily = nlFamily;
+    interceptedSocket->portId = interceptorNlPid;
+
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus NetlinkInterceptor::closeSocket(
+    const AidlInterceptedSocket& interceptedSocket) {
+    InterceptedSocket sock(interceptedSocket);
+
+    auto interceptorIt = mClientMap.find(sock);
+    if (interceptorIt == mClientMap.end()) {
+        LOG(ERROR) << "closeSocket Failed! No such socket " << sock;
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+    mClientMap.erase(interceptorIt);
+
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus NetlinkInterceptor::subscribeGroup(
+    const AidlInterceptedSocket& interceptedSocket, int32_t nlGroupAidl) {
+    InterceptedSocket sock(interceptedSocket);
+    auto nlGroup = static_cast<uint32_t>(nlGroupAidl);
+
+    auto interceptorIt = mClientMap.find(sock);
+    if (interceptorIt == mClientMap.end()) {
+        LOG(ERROR) << "subscribeGroup failed! No such socket " << sock;
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+
+    auto& interceptor = interceptorIt->second;
+    if (!interceptor->subscribeGroup(nlGroup)) {
+        LOG(ERROR) << "Failed to subscribe " << sock << " to " << nlGroup;
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus NetlinkInterceptor::unsubscribeGroup(
+    const AidlInterceptedSocket& interceptedSocket, int32_t nlGroupAidl) {
+    InterceptedSocket sock(interceptedSocket);
+    auto nlGroup = static_cast<uint32_t>(nlGroupAidl);
+
+    auto interceptorIt = mClientMap.find(sock);
+    if (interceptorIt == mClientMap.end()) {
+        LOG(ERROR) << "unsubscribeGroup failed! No such socket " << sock;
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+
+    auto& interceptor = interceptorIt->second;
+    if (!interceptor->unsubscribeGroup(nlGroup)) {
+        LOG(ERROR) << "Failed to unsubscribe " << sock << " from " << nlGroup;
+        return ndk::ScopedAStatus(AStatus_fromStatus(::android::UNKNOWN_ERROR));
+    }
+    return ndk::ScopedAStatus::ok();
+}
+}  // namespace android::nlinterceptor
diff --git a/wifi/netlinkinterceptor/aidl/default/NetlinkInterceptor.h b/wifi/netlinkinterceptor/aidl/default/NetlinkInterceptor.h
new file mode 100644
index 0000000..8345654
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/NetlinkInterceptor.h
@@ -0,0 +1,57 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <aidl/android/hardware/net/nlinterceptor/BnInterceptor.h>
+#include <libnlinterceptor/libnlinterceptor.h>
+
+#include <map>
+
+#include "InterceptorRelay.h"
+
+namespace android::nlinterceptor {
+
+class NetlinkInterceptor
+    : public ::aidl::android::hardware::net::nlinterceptor::BnInterceptor {
+    using ClientMap =
+        std::map<::android::nlinterceptor::InterceptedSocket,
+                 std::unique_ptr<::android::nlinterceptor::InterceptorRelay>>;
+
+    using AidlInterceptedSocket =
+        ::aidl::android::hardware::net::nlinterceptor::InterceptedSocket;
+
+   public:
+    ndk::ScopedAStatus createSocket(
+        int32_t nlFamily, int32_t clientNlPid, const std::string& clientName,
+        AidlInterceptedSocket* interceptedSocket) override;
+
+    ndk::ScopedAStatus closeSocket(
+        const AidlInterceptedSocket& interceptedSocket) override;
+
+    ndk::ScopedAStatus subscribeGroup(
+        const AidlInterceptedSocket& interceptedSocket,
+        int32_t nlGroup) override;
+
+    ndk::ScopedAStatus unsubscribeGroup(
+        const AidlInterceptedSocket& interceptedSocket,
+        int32_t nlGroup) override;
+
+   private:
+    ClientMap mClientMap;
+};
+
+}  // namespace android::nlinterceptor
diff --git a/wifi/netlinkinterceptor/aidl/default/OWNERS b/wifi/netlinkinterceptor/aidl/default/OWNERS
new file mode 100644
index 0000000..b738dac
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/OWNERS
@@ -0,0 +1,2 @@
+chrisweir@google.com
+twasilczyk@google.com
diff --git a/wifi/netlinkinterceptor/aidl/default/nlinterceptor-default.rc b/wifi/netlinkinterceptor/aidl/default/nlinterceptor-default.rc
new file mode 100644
index 0000000..353cb27
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/nlinterceptor-default.rc
@@ -0,0 +1,4 @@
+service nlinterceptor /vendor/bin/hw/android.hardware.net.nlinterceptor-service.default
+    class hal
+    user root
+    group system inet
diff --git a/wifi/netlinkinterceptor/aidl/default/nlinterceptor-default.xml b/wifi/netlinkinterceptor/aidl/default/nlinterceptor-default.xml
new file mode 100644
index 0000000..d7d257e
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/nlinterceptor-default.xml
@@ -0,0 +1,9 @@
+<manifest version="1.0" type="device">
+    <hal format="aidl">
+        <name>android.hardware.net.nlinterceptor</name>
+        <interface>
+            <name>IInterceptor</name>
+            <instance>default</instance>
+        </interface>
+    </hal>
+</manifest>
diff --git a/wifi/netlinkinterceptor/aidl/default/service.cpp b/wifi/netlinkinterceptor/aidl/default/service.cpp
new file mode 100644
index 0000000..2aec3a5
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/service.cpp
@@ -0,0 +1,47 @@
+/*
+ * 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.
+ */
+
+#include <android-base/logging.h>
+#include <android/binder_manager.h>
+#include <android/binder_process.h>
+
+#include "NetlinkInterceptor.h"
+
+namespace android::nlinterceptor {
+using namespace std::string_literals;
+
+static void service() {
+    base::SetDefaultTag("nlinterceptor");
+    base::SetMinimumLogSeverity(base::VERBOSE);
+    LOG(DEBUG) << "Netlink Interceptor service starting...";
+
+    // TODO(202549296): Sometimes this causes an Address Sanitizer error.
+    auto interceptor = ndk::SharedRefBase::make<NetlinkInterceptor>();
+    const auto instance = NetlinkInterceptor::descriptor + "/default"s;
+    const auto status = AServiceManager_addService(
+        interceptor->asBinder().get(), instance.c_str());
+    CHECK(status == STATUS_OK);
+
+    ABinderProcess_joinThreadPool();
+    LOG(FATAL) << "Netlink Interceptor has stopped";
+}
+
+}  // namespace android::nlinterceptor
+
+int main() {
+    ::android::nlinterceptor::service();
+    return 0;
+}
diff --git a/wifi/netlinkinterceptor/aidl/default/util.cpp b/wifi/netlinkinterceptor/aidl/default/util.cpp
new file mode 100644
index 0000000..c734747
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/util.cpp
@@ -0,0 +1,29 @@
+/*
+ * 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.
+ */
+
+#include "util.h"
+
+#include <poll.h>
+
+namespace android::nlinterceptor {
+
+bool isSocketReadable(const short revents) { return 0 != (revents & POLLIN); }
+
+bool isSocketBad(const short revents) {
+    return 0 != (revents & (POLLERR | POLLHUP | POLLNVAL));
+}
+
+}  // namespace android::nlinterceptor
diff --git a/wifi/netlinkinterceptor/aidl/default/util.h b/wifi/netlinkinterceptor/aidl/default/util.h
new file mode 100644
index 0000000..9b8ec63
--- /dev/null
+++ b/wifi/netlinkinterceptor/aidl/default/util.h
@@ -0,0 +1,52 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <android-base/macros.h>
+
+#include <functional>
+
+namespace android::nlinterceptor {
+
+/**
+ * Handy-dandy helper to get the size of a statically initialized array.
+ *
+ * \param N the array to get the size of.
+ * \return the size of the array.
+ */
+template <typename T, size_t N>
+size_t countof(T (&)[N]) {
+    return N;
+}
+
+/**
+ * Helper to check if socket is readable (POLLIN is set).
+ *
+ * \param revents pollfd.revents value to check.
+ * \return true if socket is ready to read.
+ */
+bool isSocketReadable(short revents);
+
+/**
+ * Helper to check if socket is bad (POLLERR, POLLHUP or POLLNVAL is set).
+ *
+ * \param revents pollfd.revents value to check.
+ * \return true if socket is bad.
+ */
+bool isSocketBad(short revents);
+
+}  // namespace android::nlinterceptor
diff --git a/wifi/netlinkinterceptor/libnlinterceptor/Android.bp b/wifi/netlinkinterceptor/libnlinterceptor/Android.bp
new file mode 100644
index 0000000..a5e1766
--- /dev/null
+++ b/wifi/netlinkinterceptor/libnlinterceptor/Android.bp
@@ -0,0 +1,56 @@
+//
+// 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.
+//
+
+cc_defaults {
+    name: "nlinterceptor@defaults",
+    cpp_std: "experimental",
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Wsuggest-override",
+        "-Werror",
+    ],
+    shared_libs: [
+        "libbase",
+        "libutils",
+    ],
+    sanitize: {
+        address: true,
+        undefined: true,
+        all_undefined: true,
+        fuzzer: true,
+        cfi: true,
+        integer_overflow: true,
+        scs: true,
+    },
+    strip: {
+        keep_symbols_and_debug_frame: true,
+    },
+}
+
+cc_library_static {
+    name: "libnlinterceptor",
+    defaults: ["nlinterceptor@defaults"],
+    vendor_available: true,
+    shared_libs: [
+        "android.hardware.net.nlinterceptor-V1-ndk",
+        "libbinder_ndk",
+    ],
+    srcs: [
+        "libnlinterceptor.cpp",
+    ],
+    export_include_dirs: ["include"],
+}
diff --git a/wifi/netlinkinterceptor/libnlinterceptor/include/libnlinterceptor/libnlinterceptor.h b/wifi/netlinkinterceptor/libnlinterceptor/include/libnlinterceptor/libnlinterceptor.h
new file mode 100644
index 0000000..ac8653e
--- /dev/null
+++ b/wifi/netlinkinterceptor/libnlinterceptor/include/libnlinterceptor/libnlinterceptor.h
@@ -0,0 +1,131 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+
+#include <aidl/android/hardware/net/nlinterceptor/InterceptedSocket.h>
+#include <android-base/unique_fd.h>
+#include <linux/netlink.h>
+
+#include <optional>
+#include <string>
+
+namespace android::nlinterceptor {
+
+/**
+ * Wrapper structure to uniquely identifies a socket that Netlink Interceptor
+ * has allocated for us.
+ */
+struct InterceptedSocket {
+    uint32_t nlFamily;
+    uint32_t portId;
+
+    InterceptedSocket(
+        ::aidl::android::hardware::net::nlinterceptor::InterceptedSocket sock);
+    InterceptedSocket(uint32_t nlFamily, uint32_t portId);
+
+    bool operator<(const InterceptedSocket& other) const;
+    operator sockaddr_nl() const;
+    operator ::aidl::android::hardware::net::nlinterceptor::InterceptedSocket()
+        const;
+};
+
+/**
+ * Output stream operator for InterceptedSocket
+ */
+std::ostream& operator<<(std::ostream& os, const InterceptedSocket& sock);
+
+/**
+ * Checks if an instance Netlink Interceptor exists.
+ *
+ * \return true if supported, false if not.
+ */
+bool isEnabled();
+
+/**
+ * Asks Netlink Interceptor to allocate a socket to which we can send Netlink
+ * traffic.
+ *
+ * \param clientSocket - File descriptor for the client's Netlink socket.
+ * \param clientName - Human readable name of the client application.
+ * \return Identifier for the socket created by Netlink Interceptor, nullopt on
+ * error.
+ */
+std::optional<InterceptedSocket> createSocket(base::borrowed_fd clientSocket,
+                                              const std::string& clientName);
+
+/**
+ * Asks Netlink Interceptor to close a socket that it created for us previously,
+ * if it exists.
+ *
+ * \param sock - Identifier for the socket created by Netlink Interceptor.
+ */
+void closeSocket(const InterceptedSocket& sock);
+
+/**
+ * Asks Netlink Interceptor to subscribe a socket that it created for us
+ * previously to a specified multicast group.
+ *
+ * \param sock - Identifier for the socket created by Netlink Interceptor.
+ * \param group - A single Netlink multicast group for which we would like to
+ * receive events.
+ * \return true for success, false if something went wrong.
+ */
+bool subscribe(const InterceptedSocket& sock, uint32_t group);
+
+/**
+ * Asks Netlink Interceptor to unsubscribe a socket that it created for us
+ * previously from a specified multicast group.
+ *
+ * \param sock - Identifier for the socket created by Netlink Interceptor.
+ * \param group - A single Netlink multicast group for which we no longer wish
+ * to receive events.
+ * \return true for success, false if something went wrong.
+ */
+bool unsubscribe(const InterceptedSocket& sock, uint32_t group);
+}  // namespace android::nlinterceptor
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// C wrappers for libnlinterceptor
+struct android_nlinterceptor_InterceptedSocket {
+    uint32_t nlFamily;
+    uint32_t portId;
+};
+
+bool android_nlinterceptor_isEnabled();
+
+bool android_nlinterceptor_createSocket(
+    int clientSocketFd, const char* clientName,
+    struct android_nlinterceptor_InterceptedSocket* interceptedSocket);
+
+void android_nlinterceptor_closeSocket(
+    const struct android_nlinterceptor_InterceptedSocket* sock);
+
+bool android_nlinterceptor_subscribe(
+    const struct android_nlinterceptor_InterceptedSocket* sock, uint32_t group);
+
+bool android_nlinterceptor_unsubscribe(
+    const struct android_nlinterceptor_InterceptedSocket* sock, uint32_t group);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/wifi/netlinkinterceptor/libnlinterceptor/libnlinterceptor.cpp b/wifi/netlinkinterceptor/libnlinterceptor/libnlinterceptor.cpp
new file mode 100644
index 0000000..575f900
--- /dev/null
+++ b/wifi/netlinkinterceptor/libnlinterceptor/libnlinterceptor.cpp
@@ -0,0 +1,174 @@
+/*
+ * 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.
+ */
+
+#include <aidl/android/hardware/net/nlinterceptor/IInterceptor.h>
+#include <android-base/logging.h>
+#include <android-base/macros.h>
+#include <android/binder_manager.h>
+#include <libnlinterceptor/libnlinterceptor.h>
+#include <linux/netlink.h>
+
+#include <mutex>
+
+namespace android::nlinterceptor {
+using namespace std::string_literals;
+using namespace ::aidl::android::hardware::net::nlinterceptor;
+using base::borrowed_fd;
+using AidlInterceptedSocket =
+    ::aidl::android::hardware::net::nlinterceptor::InterceptedSocket;
+
+static const auto kServiceName = IInterceptor::descriptor + "/default"s;
+
+InterceptedSocket::InterceptedSocket(
+    ::aidl::android::hardware::net::nlinterceptor::InterceptedSocket sock)
+    : nlFamily(sock.nlFamily), portId(sock.portId) {}
+
+InterceptedSocket::InterceptedSocket(uint32_t nlFamily, uint32_t portId)
+    : nlFamily(nlFamily), portId(portId) {}
+
+std::ostream& operator<<(std::ostream& os, const InterceptedSocket& sock) {
+    return os << "family: " << sock.nlFamily << ", portId: " << sock.portId;
+}
+
+bool InterceptedSocket::operator<(const InterceptedSocket& other) const {
+    if (nlFamily != other.nlFamily) {
+        return nlFamily < other.nlFamily;
+    }
+    return portId < other.portId;
+}
+
+InterceptedSocket::operator sockaddr_nl() const {
+    return {
+        .nl_family = AF_NETLINK,
+        .nl_pad = 0,
+        .nl_pid = portId,
+        .nl_groups = 0,
+    };
+}
+
+InterceptedSocket::operator AidlInterceptedSocket() const {
+    return {
+        .nlFamily = static_cast<int32_t>(nlFamily),
+        .portId = static_cast<int32_t>(portId),
+    };
+}
+
+bool isEnabled() {
+    static std::mutex supportedMutex;
+    static std::optional<bool> interceptorSupported;
+    // Avoid querying service manager when we can cache the result.
+    if (interceptorSupported.has_value()) return *interceptorSupported;
+    std::lock_guard lock(supportedMutex);
+    if (interceptorSupported.has_value()) return *interceptorSupported;
+
+    if (!AServiceManager_isDeclared(kServiceName.c_str())) {
+        interceptorSupported = false;
+        return false;
+    }
+    interceptorSupported = true;
+    return true;
+}
+
+static IInterceptor& getInstance() {
+    static std::mutex instanceMutex;
+    static std::shared_ptr<IInterceptor> interceptorInstance;
+    CHECK(isEnabled()) << "Can't getInstance! Interceptor not supported!";
+    // Don't overwrite the pointer once we've acquired it.
+    if (interceptorInstance != nullptr) return *interceptorInstance;
+    std::lock_guard lock(instanceMutex);
+    if (interceptorInstance != nullptr) return *interceptorInstance;
+    interceptorInstance = IInterceptor::fromBinder(
+        ndk::SpAIBinder(AServiceManager_waitForService(kServiceName.c_str())));
+    CHECK(interceptorInstance != nullptr)
+        << "Failed to get Netlink Interceptor service!";
+    return *interceptorInstance;
+}
+
+std::optional<InterceptedSocket> createSocket(borrowed_fd clientSocket,
+                                              const std::string& clientName) {
+    sockaddr_nl nladdr = {};
+    socklen_t nlsize = sizeof(nladdr);
+    if (getsockname(clientSocket.get(), reinterpret_cast<sockaddr*>(&nladdr),
+                    &nlsize) < 0) {
+        PLOG(ERROR) << "Failed to get pid of fd passed by " << clientName;
+        return std::nullopt;
+    }
+
+    ::aidl::android::hardware::net::nlinterceptor::InterceptedSocket
+        interceptedSocket;
+    auto aidlStatus = getInstance().createSocket(
+        nladdr.nl_family, nladdr.nl_pid, clientName, &interceptedSocket);
+    if (!aidlStatus.isOk()) {
+        return std::nullopt;
+    }
+
+    return InterceptedSocket{nladdr.nl_family,
+                             uint32_t(interceptedSocket.portId)};
+}
+
+void closeSocket(const InterceptedSocket& sock) {
+    auto aidlStatus = getInstance().closeSocket(sock);
+    if (!aidlStatus.isOk()) {
+        LOG(ERROR) << "Failed to close socket with pid = " << sock.portId;
+    }
+}
+
+bool subscribe(const InterceptedSocket& sock, uint32_t group) {
+    auto aidlStatus = getInstance().subscribeGroup(sock, group);
+    return aidlStatus.isOk();
+}
+
+bool unsubscribe(const InterceptedSocket& sock, uint32_t group) {
+    auto aidlStatus = getInstance().unsubscribeGroup(sock, group);
+    return aidlStatus.isOk();
+}
+
+extern "C" bool android_nlinterceptor_isEnabled() { return isEnabled(); }
+
+extern "C" bool android_nlinterceptor_createSocket(
+    int clientSocketFd, const char* clientName,
+    android_nlinterceptor_InterceptedSocket* interceptedSocket) {
+    if (!clientName || clientSocketFd <= 0) return false;
+    const auto maybeSocket =
+        createSocket(borrowed_fd(clientSocketFd), clientName);
+    if (!maybeSocket) return false;
+    *interceptedSocket = {.nlFamily = maybeSocket->nlFamily,
+                          .portId = maybeSocket->portId};
+    return true;
+}
+
+extern "C" void android_nlinterceptor_closeSocket(
+    const android_nlinterceptor_InterceptedSocket* sock) {
+    if (!sock) {
+        LOG(ERROR) << "Can't close socket identified by a null pointer!";
+        return;
+    }
+    closeSocket({sock->nlFamily, sock->portId});
+}
+
+extern "C" bool android_nlinterceptor_subscribe(
+    const android_nlinterceptor_InterceptedSocket* sock, uint32_t group) {
+    if (!sock) return false;
+    return subscribe({sock->nlFamily, sock->portId}, group);
+}
+
+extern "C" bool android_nlinterceptor_unsubscribe(
+    const android_nlinterceptor_InterceptedSocket* sock, uint32_t group) {
+    if (!sock) return false;
+    return unsubscribe({sock->nlFamily, sock->portId}, group);
+}
+
+}  // namespace android::nlinterceptor