diff --git a/staticlibs/testutils/devicetests/NSResponder.kt b/staticlibs/testutils/devicetests/NSResponder.kt
new file mode 100644
index 0000000..f7619cd
--- /dev/null
+++ b/staticlibs/testutils/devicetests/NSResponder.kt
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2023 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.testutils
+
+import android.net.MacAddress
+import android.util.Log
+import com.android.net.module.util.Ipv6Utils
+import com.android.net.module.util.NetworkStackConstants.ETHER_HEADER_LEN
+import com.android.net.module.util.NetworkStackConstants.ICMPV6_ND_OPTION_TLLA
+import com.android.net.module.util.NetworkStackConstants.NEIGHBOR_ADVERTISEMENT_FLAG_SOLICITED
+import com.android.net.module.util.Struct
+import com.android.net.module.util.structs.Icmpv6Header
+import com.android.net.module.util.structs.Ipv6Header
+import com.android.net.module.util.structs.LlaOption
+import com.android.net.module.util.structs.NsHeader
+import com.android.testutils.PacketReflector.IPV6_HEADER_LENGTH
+import java.lang.IllegalArgumentException
+import java.net.Inet6Address
+import java.nio.ByteBuffer
+
+private const val NS_TYPE = 135.toShort()
+
+/**
+ * A class that can be used to reply to Neighbor Solicitation packets on a [TapPacketReader].
+ */
+class NSResponder(
+    reader: TapPacketReader,
+    table: Map<Inet6Address, MacAddress>,
+    name: String = NSResponder::class.java.simpleName
+) : PacketResponder(reader, Icmpv6Filter(), name) {
+    companion object {
+        private val TAG = NSResponder::class.simpleName
+    }
+
+    // Copy the map if not already immutable (toMap) to make sure it is not modified
+    private val table = table.toMap()
+
+    override fun replyToPacket(packet: ByteArray, reader: TapPacketReader) {
+        if (packet.size < IPV6_HEADER_LENGTH) {
+            return
+        }
+        val buf = ByteBuffer.wrap(packet, ETHER_HEADER_LEN, packet.size - ETHER_HEADER_LEN)
+        val ipv6Header = parseOrLog(Ipv6Header::class.java, buf) ?: return
+        val icmpHeader = parseOrLog(Icmpv6Header::class.java, buf) ?: return
+        if (icmpHeader.type != NS_TYPE) {
+            return
+        }
+        val ns = parseOrLog(NsHeader::class.java, buf) ?: return
+        val replyMacAddr = table[ns.target] ?: return
+        val slla = parseOrLog(LlaOption::class.java, buf) ?: return
+        val requesterMac = slla.linkLayerAddress
+
+        val tlla = LlaOption.build(ICMPV6_ND_OPTION_TLLA.toByte(), replyMacAddr)
+        reader.sendResponse(Ipv6Utils.buildNaPacket(
+            replyMacAddr /* srcMac */,
+            requesterMac /* dstMac */,
+            ns.target /* srcIp */,
+            ipv6Header.srcIp /* dstIp */,
+            NEIGHBOR_ADVERTISEMENT_FLAG_SOLICITED,
+            ns.target,
+            tlla))
+    }
+
+    private fun <T> parseOrLog(clazz: Class<T>, buf: ByteBuffer): T? where T : Struct {
+        return try {
+            Struct.parse(clazz, buf)
+        } catch (e: IllegalArgumentException) {
+            Log.e(TAG, "Invalid ${clazz.simpleName} in ICMPv6 packet", e)
+            null
+        }
+    }
+}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/DeviceConfigRule.kt b/staticlibs/testutils/devicetests/com/android/testutils/DeviceConfigRule.kt
index 3d98cc3..68248ca 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/DeviceConfigRule.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/DeviceConfigRule.kt
@@ -22,12 +22,12 @@
 import android.util.Log
 import com.android.modules.utils.build.SdkLevel
 import com.android.testutils.FunctionalUtils.ThrowingRunnable
-import org.junit.rules.TestRule
-import org.junit.runner.Description
-import org.junit.runners.model.Statement
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.Executor
 import java.util.concurrent.TimeUnit
+import org.junit.rules.TestRule
+import org.junit.runner.Description
+import org.junit.runners.model.Statement
 
 private val TAG = DeviceConfigRule::class.simpleName
 
@@ -147,11 +147,11 @@
         return tryTest {
             runAsShell(*readWritePermissions) {
                 DeviceConfig.addOnPropertiesChangedListener(
-                        DeviceConfig.NAMESPACE_CONNECTIVITY,
+                        namespace,
                         inlineExecutor,
                         listener)
                 DeviceConfig.setProperty(
-                        DeviceConfig.NAMESPACE_CONNECTIVITY,
+                        namespace,
                         key,
                         value,
                         false /* makeDefault */)