diff --git a/staticlibs/device/com/android/net/module/util/netlink/IpSecStructXfrmAddressT.java b/staticlibs/device/com/android/net/module/util/netlink/IpSecStructXfrmAddressT.java
new file mode 100644
index 0000000..4c19887
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/netlink/IpSecStructXfrmAddressT.java
@@ -0,0 +1,84 @@
+/*
+ * 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.net.module.util.netlink;
+
+import android.system.OsConstants;
+
+import androidx.annotation.NonNull;
+
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.Struct.Field;
+import com.android.net.module.util.Struct.Type;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+/**
+ * Struct xfrm_address_t
+ *
+ * <p>see include/uapi/linux/xfrm.h
+ *
+ * <pre>
+ * typedef union {
+ *      __be32 a4;
+ *      __be32 a6[4];
+ *      struct in6_addr in6;
+ * } xfrm_address_t;
+ * </pre>
+ *
+ * @hide
+ */
+public class IpSecStructXfrmAddressT extends Struct {
+    private static final int IPV4_ADDRESS_LEN = 4;
+
+    public static final int STRUCT_SIZE = 16;
+
+    @Field(order = 0, type = Type.ByteArray, arraysize = STRUCT_SIZE)
+    public final byte[] address;
+
+    // Constructor that allows Strutc.parse(Class<T>, ByteBuffer) to work
+    public IpSecStructXfrmAddressT(@NonNull byte[] address) {
+        this.address = address.clone();
+    }
+
+    // Constructor to build a new message
+    public IpSecStructXfrmAddressT(@NonNull InetAddress inetAddress) {
+        this.address = new byte[STRUCT_SIZE];
+        final byte[] addressBytes = inetAddress.getAddress();
+        System.arraycopy(addressBytes, 0, address, 0, addressBytes.length);
+    }
+
+    /** Return the address in InetAddress */
+    public InetAddress getAddress(int family) {
+        final byte[] addressBytes;
+        if (family == OsConstants.AF_INET6) {
+            addressBytes = this.address;
+        } else if (family == OsConstants.AF_INET) {
+            addressBytes = new byte[IPV4_ADDRESS_LEN];
+            System.arraycopy(this.address, 0, addressBytes, 0, addressBytes.length);
+        } else {
+            throw new IllegalArgumentException("Invalid IP family " + family);
+        }
+
+        try {
+            return InetAddress.getByAddress(addressBytes);
+        } catch (UnknownHostException e) {
+            // This should never happen
+            throw new IllegalArgumentException(
+                    "Illegal length of IP address " + addressBytes.length, e);
+        }
+    }
+}
diff --git a/staticlibs/device/com/android/net/module/util/netlink/IpSecStructXfrmUsersaId.java b/staticlibs/device/com/android/net/module/util/netlink/IpSecStructXfrmUsersaId.java
new file mode 100644
index 0000000..6f7b656
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/netlink/IpSecStructXfrmUsersaId.java
@@ -0,0 +1,81 @@
+/*
+ * 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.net.module.util.netlink;
+
+import androidx.annotation.NonNull;
+
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.Struct.Field;
+import com.android.net.module.util.Struct.Type;
+
+import java.net.InetAddress;
+
+/**
+ * Struct xfrm_usersa_id
+ *
+ * <p>see include/uapi/linux/xfrm.h
+ *
+ * <pre>
+ * struct xfrm_usersa_id {
+ *      xfrm_address_t      daddr;
+ *      __be32              spi;
+ *      __u16               family;
+ *      __u8                proto;
+ * };
+ * </pre>
+ *
+ * @hide
+ */
+public class IpSecStructXfrmUsersaId extends Struct {
+    public static final int STRUCT_SIZE = 24;
+
+    @Field(order = 0, type = Type.ByteArray, arraysize = 16)
+    public final byte[] nestedStructDAddr; // xfrm_address_t
+
+    @Field(order = 1, type = Type.UBE32)
+    public final long spi;
+
+    @Field(order = 2, type = Type.U16)
+    public final int family;
+
+    @Field(order = 3, type = Type.U8, padding = 1)
+    public final short proto;
+
+    @Computed private final IpSecStructXfrmAddressT mDestXfrmAddressT;
+
+    // Constructor that allows Strutc.parse(Class<T>, ByteBuffer) to work
+    public IpSecStructXfrmUsersaId(
+            @NonNull byte[] nestedStructDAddr, long spi, int family, short proto) {
+        this.nestedStructDAddr = nestedStructDAddr.clone();
+        this.spi = spi;
+        this.family = family;
+        this.proto = proto;
+
+        mDestXfrmAddressT = new IpSecStructXfrmAddressT(this.nestedStructDAddr);
+    }
+
+    // Constructor to build a new message
+    public IpSecStructXfrmUsersaId(
+            @NonNull InetAddress destAddress, long spi, int family, short proto) {
+        this(new IpSecStructXfrmAddressT(destAddress).writeToBytes(), spi, family, proto);
+    }
+
+    /** Return the destination address */
+    public InetAddress getDestAddress() {
+        return mDestXfrmAddressT.getAddress(family);
+    }
+}
diff --git a/staticlibs/device/com/android/net/module/util/netlink/IpSecXfrmNetlinkMessage.java b/staticlibs/device/com/android/net/module/util/netlink/IpSecXfrmNetlinkMessage.java
new file mode 100644
index 0000000..8ad784b
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/netlink/IpSecXfrmNetlinkMessage.java
@@ -0,0 +1,36 @@
+/*
+ * 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.net.module.util.netlink;
+
+import androidx.annotation.NonNull;
+
+/** Base calss for XFRM netlink messages */
+// Developer notes: The Linux kernel includes a number of XFRM structs that are not standard netlink
+// attributes (e.g., xfrm_usersa_id). These structs are unlikely to change size, so this XFRM
+// netlink message implementation assumes their sizes will remain stable. If any non-attribute
+// struct size changes, it should be caught by CTS and then developers should add
+// kernel-version-based behvaiours.
+public abstract class IpSecXfrmNetlinkMessage extends NetlinkMessage {
+    // TODO: STOPSHIP: b/308011229 Remove it when OsConstants.IPPROTO_ESP is exposed
+    public static final int IPPROTO_ESP = 50;
+
+    public IpSecXfrmNetlinkMessage(@NonNull StructNlMsgHdr header) {
+        super(header);
+    }
+
+    // TODO: Add the support for parsing messages
+}
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/netlink/IpSecStructXfrmUsersaIdTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/netlink/IpSecStructXfrmUsersaIdTest.java
new file mode 100644
index 0000000..4266f68
--- /dev/null
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/netlink/IpSecStructXfrmUsersaIdTest.java
@@ -0,0 +1,76 @@
+/*
+ * 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.net.module.util.netlink;
+
+import static com.android.net.module.util.netlink.IpSecXfrmNetlinkMessage.IPPROTO_ESP;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+import android.net.InetAddresses;
+import android.system.OsConstants;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.net.module.util.HexDump;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.net.InetAddress;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class IpSecStructXfrmUsersaIdTest {
+    private static final String EXPECTED_HEX_STRING =
+            "C0000201000000000000000000000000" + "7768440002003200";
+    private static final byte[] EXPECTED_HEX = HexDump.hexStringToByteArray(EXPECTED_HEX_STRING);
+
+    private static final InetAddress DEST_ADDRESS = InetAddresses.parseNumericAddress("192.0.2.1");
+    private static final long SPI = 0x77684400;
+    private static final int FAMILY = OsConstants.AF_INET;
+    private static final short PROTO = IPPROTO_ESP;
+
+    @Test
+    public void testEncode() throws Exception {
+        final IpSecStructXfrmUsersaId struct =
+                new IpSecStructXfrmUsersaId(DEST_ADDRESS, SPI, FAMILY, PROTO);
+
+        ByteBuffer buffer = ByteBuffer.allocate(EXPECTED_HEX.length);
+        buffer.order(ByteOrder.nativeOrder());
+        struct.writeToByteBuffer(buffer);
+
+        assertArrayEquals(EXPECTED_HEX, buffer.array());
+    }
+
+    @Test
+    public void testDecode() throws Exception {
+        final ByteBuffer buffer = ByteBuffer.wrap(EXPECTED_HEX);
+        buffer.order(ByteOrder.nativeOrder());
+
+        final IpSecStructXfrmUsersaId struct =
+                IpSecStructXfrmUsersaId.parse(IpSecStructXfrmUsersaId.class, buffer);
+
+        assertEquals(DEST_ADDRESS, struct.getDestAddress());
+        assertEquals(SPI, struct.spi);
+        assertEquals(FAMILY, struct.family);
+        assertEquals(PROTO, struct.proto);
+    }
+}