diff --git a/staticlibs/framework/com/android/net/module/util/IpUtils.java b/staticlibs/framework/com/android/net/module/util/IpUtils.java
new file mode 100644
index 0000000..54b4cdf
--- /dev/null
+++ b/staticlibs/framework/com/android/net/module/util/IpUtils.java
@@ -0,0 +1,151 @@
+/*
+ * Copyright (C) 2015 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;
+
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.nio.BufferOverflowException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.nio.ShortBuffer;
+
+import static android.system.OsConstants.IPPROTO_TCP;
+import static android.system.OsConstants.IPPROTO_UDP;
+
+/**
+ * @hide
+ */
+public class IpUtils {
+    /**
+     * Converts a signed short value to an unsigned int value.  Needed
+     * because Java does not have unsigned types.
+     */
+    private static int intAbs(short v) {
+        return v & 0xFFFF;
+    }
+
+    /**
+     * Performs an IP checksum (used in IP header and across UDP
+     * payload) on the specified portion of a ByteBuffer.  The seed
+     * allows the checksum to commence with a specified value.
+     */
+    private static int checksum(ByteBuffer buf, int seed, int start, int end) {
+        int sum = seed;
+        final int bufPosition = buf.position();
+
+        // set position of original ByteBuffer, so that the ShortBuffer
+        // will be correctly initialized
+        buf.position(start);
+        ShortBuffer shortBuf = buf.asShortBuffer();
+
+        // re-set ByteBuffer position
+        buf.position(bufPosition);
+
+        final int numShorts = (end - start) / 2;
+        for (int i = 0; i < numShorts; i++) {
+            sum += intAbs(shortBuf.get(i));
+        }
+        start += numShorts * 2;
+
+        // see if a singleton byte remains
+        if (end != start) {
+            short b = buf.get(start);
+
+            // make it unsigned
+            if (b < 0) {
+                b += 256;
+            }
+
+            sum += b * 256;
+        }
+
+        sum = ((sum >> 16) & 0xFFFF) + (sum & 0xFFFF);
+        sum = ((sum + ((sum >> 16) & 0xFFFF)) & 0xFFFF);
+        int negated = ~sum;
+        return intAbs((short) negated);
+    }
+
+    private static int pseudoChecksumIPv4(
+            ByteBuffer buf, int headerOffset, int protocol, int transportLen) {
+        int partial = protocol + transportLen;
+        partial += intAbs(buf.getShort(headerOffset + 12));
+        partial += intAbs(buf.getShort(headerOffset + 14));
+        partial += intAbs(buf.getShort(headerOffset + 16));
+        partial += intAbs(buf.getShort(headerOffset + 18));
+        return partial;
+    }
+
+    private static int pseudoChecksumIPv6(
+            ByteBuffer buf, int headerOffset, int protocol, int transportLen) {
+        int partial = protocol + transportLen;
+        for (int offset = 8; offset < 40; offset += 2) {
+            partial += intAbs(buf.getShort(headerOffset + offset));
+        }
+        return partial;
+    }
+
+    private static byte ipversion(ByteBuffer buf, int headerOffset) {
+        return (byte) ((buf.get(headerOffset) & (byte) 0xf0) >> 4);
+   }
+
+    public static short ipChecksum(ByteBuffer buf, int headerOffset) {
+        byte ihl = (byte) (buf.get(headerOffset) & 0x0f);
+        return (short) checksum(buf, 0, headerOffset, headerOffset + ihl * 4);
+    }
+
+    private static short transportChecksum(ByteBuffer buf, int protocol,
+            int ipOffset, int transportOffset, int transportLen) {
+        if (transportLen < 0) {
+            throw new IllegalArgumentException("Transport length < 0: " + transportLen);
+        }
+        int sum;
+        byte ver = ipversion(buf, ipOffset);
+        if (ver == 4) {
+            sum = pseudoChecksumIPv4(buf, ipOffset, protocol, transportLen);
+        } else if (ver == 6) {
+            sum = pseudoChecksumIPv6(buf, ipOffset, protocol, transportLen);
+        } else {
+            throw new UnsupportedOperationException("Checksum must be IPv4 or IPv6");
+        }
+
+        sum = checksum(buf, sum, transportOffset, transportOffset + transportLen);
+        if (protocol == IPPROTO_UDP && sum == 0) {
+            sum = (short) 0xffff;
+        }
+        return (short) sum;
+    }
+
+    public static short udpChecksum(ByteBuffer buf, int ipOffset, int transportOffset) {
+        int transportLen = intAbs(buf.getShort(transportOffset + 4));
+        return transportChecksum(buf, IPPROTO_UDP, ipOffset, transportOffset, transportLen);
+    }
+
+    public static short tcpChecksum(ByteBuffer buf, int ipOffset, int transportOffset,
+            int transportLen) {
+        return transportChecksum(buf, IPPROTO_TCP, ipOffset, transportOffset, transportLen);
+    }
+
+    public static String addressAndPortToString(InetAddress address, int port) {
+        return String.format(
+                (address instanceof Inet6Address) ? "[%s]:%d" : "%s:%d",
+                address.getHostAddress(), port);
+    }
+
+    public static boolean isValidUdpOrTcpPort(int port) {
+        return port > 0 && port < 65536;
+    }
+}
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/IpUtilsTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/IpUtilsTest.java
new file mode 100644
index 0000000..3468309
--- /dev/null
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/IpUtilsTest.java
@@ -0,0 +1,166 @@
+/*
+ * 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 com.android.net.module.util;
+
+import static org.junit.Assert.assertEquals;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.nio.ByteBuffer;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class IpUtilsTest {
+
+    private static final int IPV4_HEADER_LENGTH = 20;
+    private static final int IPV6_HEADER_LENGTH = 40;
+    private static final int TCP_HEADER_LENGTH = 20;
+    private static final int UDP_HEADER_LENGTH = 8;
+    private static final int IP_CHECKSUM_OFFSET = 10;
+    private static final int TCP_CHECKSUM_OFFSET = 16;
+    private static final int UDP_CHECKSUM_OFFSET = 6;
+
+    private int getUnsignedByte(ByteBuffer buf, int offset) {
+        return buf.get(offset) & 0xff;
+    }
+
+    private int getChecksum(ByteBuffer buf, int offset) {
+        return getUnsignedByte(buf, offset) * 256 + getUnsignedByte(buf, offset + 1);
+    }
+
+    private void assertChecksumEquals(int expected, short actual) {
+        assertEquals(Integer.toHexString(expected), Integer.toHexString(actual & 0xffff));
+    }
+
+    // Generate test packets using Python code like this::
+    //
+    // from scapy import all as scapy
+    //
+    // def JavaPacketDefinition(bytes):
+    //   out = "        ByteBuffer packet = ByteBuffer.wrap(new byte[] {\n            "
+    //   for i in xrange(len(bytes)):
+    //     out += "(byte) 0x%02x" % ord(bytes[i])
+    //     if i < len(bytes) - 1:
+    //       if i % 4 == 3:
+    //         out += ",\n            "
+    //       else:
+    //         out += ", "
+    //   out += "\n        });"
+    //   return out
+    //
+    // packet = (scapy.IPv6(src="2001:db8::1", dst="2001:db8::2") /
+    //           scapy.UDP(sport=12345, dport=7) /
+    //           "hello")
+    // print JavaPacketDefinition(str(packet))
+
+    @Test
+    public void testIpv6TcpChecksum() throws Exception {
+        // packet = (scapy.IPv6(src="2001:db8::1", dst="2001:db8::2", tc=0x80) /
+        //           scapy.TCP(sport=12345, dport=7,
+        //                     seq=1692871236, ack=128376451, flags=16,
+        //                     window=32768) /
+        //           "hello, world")
+        ByteBuffer packet = ByteBuffer.wrap(new byte[] {
+            (byte) 0x68, (byte) 0x00, (byte) 0x00, (byte) 0x00,
+            (byte) 0x00, (byte) 0x20, (byte) 0x06, (byte) 0x40,
+            (byte) 0x20, (byte) 0x01, (byte) 0x0d, (byte) 0xb8,
+            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
+            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
+            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x01,
+            (byte) 0x20, (byte) 0x01, (byte) 0x0d, (byte) 0xb8,
+            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
+            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
+            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x02,
+            (byte) 0x30, (byte) 0x39, (byte) 0x00, (byte) 0x07,
+            (byte) 0x64, (byte) 0xe7, (byte) 0x2a, (byte) 0x44,
+            (byte) 0x07, (byte) 0xa6, (byte) 0xde, (byte) 0x83,
+            (byte) 0x50, (byte) 0x10, (byte) 0x80, (byte) 0x00,
+            (byte) 0xee, (byte) 0x71, (byte) 0x00, (byte) 0x00,
+            (byte) 0x68, (byte) 0x65, (byte) 0x6c, (byte) 0x6c,
+            (byte) 0x6f, (byte) 0x2c, (byte) 0x20, (byte) 0x77,
+            (byte) 0x6f, (byte) 0x72, (byte) 0x6c, (byte) 0x64
+        });
+
+        // Check that a valid packet has checksum 0.
+        int transportLen = packet.limit() - IPV6_HEADER_LENGTH;
+        assertEquals(0, IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen));
+
+        // Check that we can calculate the checksum from scratch.
+        int sumOffset = IPV6_HEADER_LENGTH + TCP_CHECKSUM_OFFSET;
+        int sum = getUnsignedByte(packet, sumOffset) * 256 + getUnsignedByte(packet, sumOffset + 1);
+        assertEquals(0xee71, sum);
+
+        packet.put(sumOffset, (byte) 0);
+        packet.put(sumOffset + 1, (byte) 0);
+        assertChecksumEquals(sum, IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen));
+
+        // Check that writing the checksum back into the packet results in a valid packet.
+        packet.putShort(
+            sumOffset,
+            IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen));
+        assertEquals(0, IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen));
+    }
+
+    @Test
+    public void testIpv4UdpChecksum() {
+        // packet = (scapy.IP(src="192.0.2.1", dst="192.0.2.2", tos=0x40) /
+        //           scapy.UDP(sport=32012, dport=4500) /
+        //           "\xff")
+        ByteBuffer packet = ByteBuffer.wrap(new byte[] {
+            (byte) 0x45, (byte) 0x40, (byte) 0x00, (byte) 0x1d,
+            (byte) 0x00, (byte) 0x01, (byte) 0x00, (byte) 0x00,
+            (byte) 0x40, (byte) 0x11, (byte) 0xf6, (byte) 0x8b,
+            (byte) 0xc0, (byte) 0x00, (byte) 0x02, (byte) 0x01,
+            (byte) 0xc0, (byte) 0x00, (byte) 0x02, (byte) 0x02,
+            (byte) 0x7d, (byte) 0x0c, (byte) 0x11, (byte) 0x94,
+            (byte) 0x00, (byte) 0x09, (byte) 0xee, (byte) 0x36,
+            (byte) 0xff
+        });
+
+        // Check that a valid packet has IP checksum 0 and UDP checksum 0xffff (0 is not a valid
+        // UDP checksum, so the udpChecksum rewrites 0 to 0xffff).
+        assertEquals(0, IpUtils.ipChecksum(packet, 0));
+        assertEquals((short) 0xffff, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH));
+
+        // Check that we can calculate the checksums from scratch.
+        final int ipSumOffset = IP_CHECKSUM_OFFSET;
+        final int ipSum = getChecksum(packet, ipSumOffset);
+        assertEquals(0xf68b, ipSum);
+
+        packet.put(ipSumOffset, (byte) 0);
+        packet.put(ipSumOffset + 1, (byte) 0);
+        assertChecksumEquals(ipSum, IpUtils.ipChecksum(packet, 0));
+
+        final int udpSumOffset = IPV4_HEADER_LENGTH + UDP_CHECKSUM_OFFSET;
+        final int udpSum = getChecksum(packet, udpSumOffset);
+        assertEquals(0xee36, udpSum);
+
+        packet.put(udpSumOffset, (byte) 0);
+        packet.put(udpSumOffset + 1, (byte) 0);
+        assertChecksumEquals(udpSum, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH));
+
+        // Check that writing the checksums back into the packet results in a valid packet.
+        packet.putShort(ipSumOffset, IpUtils.ipChecksum(packet, 0));
+        packet.putShort(udpSumOffset, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH));
+        assertEquals(0, IpUtils.ipChecksum(packet, 0));
+        assertEquals((short) 0xffff, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH));
+    }
+}