diff --git a/common/moduleutils/Android.bp b/common/moduleutils/Android.bp
new file mode 100644
index 0000000..6117149
--- /dev/null
+++ b/common/moduleutils/Android.bp
@@ -0,0 +1,21 @@
+//
+// Copyright (C) 2019 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.
+//
+
+// Shared utility sources to be used by multiple network modules
+filegroup {
+    name: "net-module-utils-srcs",
+    srcs: ["src/**/*.java"],
+}
\ No newline at end of file
diff --git a/common/moduleutils/src/android/net/util/SharedLog.java b/common/moduleutils/src/android/net/util/SharedLog.java
new file mode 100644
index 0000000..4fabf10
--- /dev/null
+++ b/common/moduleutils/src/android/net/util/SharedLog.java
@@ -0,0 +1,201 @@
+/*
+ * Copyright (C) 2017 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.util;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.text.TextUtils;
+import android.util.LocalLog;
+import android.util.Log;
+
+import java.io.FileDescriptor;
+import java.io.PrintWriter;
+import java.util.StringJoiner;
+
+
+/**
+ * Class to centralize logging functionality for tethering.
+ *
+ * All access to class methods other than dump() must be on the same thread.
+ *
+ * @hide
+ */
+public class SharedLog {
+    private static final int DEFAULT_MAX_RECORDS = 500;
+    private static final String COMPONENT_DELIMITER = ".";
+
+    private enum Category {
+        NONE,
+        ERROR,
+        MARK,
+        WARN,
+    };
+
+    private final LocalLog mLocalLog;
+    // The tag to use for output to the system log. This is not output to the
+    // LocalLog because that would be redundant.
+    private final String mTag;
+    // The component (or subcomponent) of a system that is sharing this log.
+    // This can grow in depth if components call forSubComponent() to obtain
+    // their SharedLog instance. The tag is not included in the component for
+    // brevity.
+    private final String mComponent;
+
+    public SharedLog(String tag) {
+        this(DEFAULT_MAX_RECORDS, tag);
+    }
+
+    public SharedLog(int maxRecords, String tag) {
+        this(new LocalLog(maxRecords), tag, tag);
+    }
+
+    private SharedLog(LocalLog localLog, String tag, String component) {
+        mLocalLog = localLog;
+        mTag = tag;
+        mComponent = component;
+    }
+
+    public String getTag() {
+        return mTag;
+    }
+
+    /**
+     * Create a SharedLog based on this log with an additional component prefix on each logged line.
+     */
+    public SharedLog forSubComponent(String component) {
+        if (!isRootLogInstance()) {
+            component = mComponent + COMPONENT_DELIMITER + component;
+        }
+        return new SharedLog(mLocalLog, mTag, component);
+    }
+
+    /**
+     * Dump the contents of this log.
+     *
+     * <p>This method may be called on any thread.
+     */
+    public void dump(FileDescriptor fd, PrintWriter writer, String[] args) {
+        mLocalLog.readOnlyLocalLog().dump(fd, writer, args);
+    }
+
+    //////
+    // Methods that both log an entry and emit it to the system log.
+    //////
+
+    /**
+     * Log an error due to an exception. This does not include the exception stacktrace.
+     *
+     * <p>The log entry will be also added to the system log.
+     * @see #e(String, Throwable)
+     */
+    public void e(Exception e) {
+        Log.e(mTag, record(Category.ERROR, e.toString()));
+    }
+
+    /**
+     * Log an error message.
+     *
+     * <p>The log entry will be also added to the system log.
+     */
+    public void e(String msg) {
+        Log.e(mTag, record(Category.ERROR, msg));
+    }
+
+    /**
+     * Log an error due to an exception, with the exception stacktrace if provided.
+     *
+     * <p>The error and exception message appear in the shared log, but the stacktrace is only
+     * logged in general log output (logcat). The log entry will be also added to the system log.
+     */
+    public void e(@NonNull String msg, @Nullable Throwable exception) {
+        if (exception == null) {
+            e(msg);
+            return;
+        }
+        Log.e(mTag, record(Category.ERROR, msg + ": " + exception.getMessage()), exception);
+    }
+
+    /**
+     * Log an informational message.
+     *
+     * <p>The log entry will be also added to the system log.
+     */
+    public void i(String msg) {
+        Log.i(mTag, record(Category.NONE, msg));
+    }
+
+    /**
+     * Log a warning message.
+     *
+     * <p>The log entry will be also added to the system log.
+     */
+    public void w(String msg) {
+        Log.w(mTag, record(Category.WARN, msg));
+    }
+
+    //////
+    // Methods that only log an entry (and do NOT emit to the system log).
+    //////
+
+    /**
+     * Log a general message to be only included in the in-memory log.
+     *
+     * <p>The log entry will *not* be added to the system log.
+     */
+    public void log(String msg) {
+        record(Category.NONE, msg);
+    }
+
+    /**
+     * Log a general, formatted message to be only included in the in-memory log.
+     *
+     * <p>The log entry will *not* be added to the system log.
+     * @see String#format(String, Object...)
+     */
+    public void logf(String fmt, Object... args) {
+        log(String.format(fmt, args));
+    }
+
+    /**
+     * Log a message with MARK level.
+     *
+     * <p>The log entry will *not* be added to the system log.
+     */
+    public void mark(String msg) {
+        record(Category.MARK, msg);
+    }
+
+    private String record(Category category, String msg) {
+        final String entry = logLine(category, msg);
+        mLocalLog.log(entry);
+        return entry;
+    }
+
+    private String logLine(Category category, String msg) {
+        final StringJoiner sj = new StringJoiner(" ");
+        if (!isRootLogInstance()) sj.add("[" + mComponent + "]");
+        if (category != Category.NONE) sj.add(category.toString());
+        return sj.add(msg).toString();
+    }
+
+    // Check whether this SharedLog instance is nominally the top level in
+    // a potential hierarchy of shared logs (the root of a tree),
+    // or is a subcomponent within the hierarchy.
+    private boolean isRootLogInstance() {
+        return TextUtils.isEmpty(mComponent) || mComponent.equals(mTag);
+    }
+}