diff --git a/include/ZeroTierSockets.h b/include/ZeroTierSockets.h
index 0710896..0af96a8 100644
--- a/include/ZeroTierSockets.h
+++ b/include/ZeroTierSockets.h
@@ -2623,6 +2623,24 @@ ZTS_API int ZTCALL zts_udp_client(const char* remote_ipstr);
  */
 ZTS_API int ZTCALL zts_set_no_delay(int fd, int enabled);
 
+/**
+ * @brief Get the last error for the given socket
+ *
+ * @param fd Socket file descriptor
+ * @return Error number defined in `zts_errno_t`. `ZTS_ERR_SERVICE` if the node
+ *     experiences a problem, `ZTS_ERR_ARG` if invalid argument. Sets `zts_errno`
+ */
+ZTS_API int ZTCALL zts_get_last_socket_error(int fd);
+
+/**
+ * @brief Return amount of data available to read from socket
+ *
+ * @param fd Socket file descriptor
+ * @return Number of bytes available to read. `ZTS_ERR_SERVICE` if the node
+ *     experiences a problem, `ZTS_ERR_ARG` if invalid argument. Sets `zts_errno`
+ */
+ZTS_API size_t ZTCALL zts_get_data_available(int fd);
+
 /**
  * @brief Return whether `TCP_NODELAY` is enabled
  *
diff --git a/pkg/nuget/ZeroTier.Sockets/ZeroTier.Sockets.x64.nuspec b/pkg/nuget/ZeroTier.Sockets/ZeroTier.Sockets.x64.nuspec
index 5502015..f8c5106 100644
--- a/pkg/nuget/ZeroTier.Sockets/ZeroTier.Sockets.x64.nuspec
+++ b/pkg/nuget/ZeroTier.Sockets/ZeroTier.Sockets.x64.nuspec
@@ -9,7 +9,7 @@
 		<license type="file">LICENSE.txt</license>
 		<icon>icon.png</icon>
 		<requireLicenseAcceptance>false</requireLicenseAcceptance>
-		<releaseNotes>Namespace adjustments, additions to Socket API, memory leak fixes.</releaseNotes>
+		<releaseNotes>Add NetworkStream. Fix errno bug</releaseNotes>
 		<description>Encrypted P2P SD-WAN networking layer (Managed C# API) [x64]</description>
 		<title>Encrypted P2P SD-WAN networking layer (Managed C# API) [x64]</title>
 		<copyright>Copyright 2021 ZeroTier, Inc.</copyright>
@@ -26,7 +26,7 @@
 		<file src="runtimes\**" target="runtimes" />
 		<file src="licenses\LICENSE.txt" target="" />
 		<file src="runtimes\win10-x64\lib\uap10.0\*.dll" target="ref\uap10.0" />
-		<file src="contentFiles\*.cs" target="contentFiles\cs\any\ZeroTier.Source.ReadOnly" /> 
+		<file src="contentFiles\*.cs" target="contentFiles\cs\any\ZeroTier.Source.ReadOnly" />
 		<file src="runtimes\win10-x64\lib\uap10.0\*.dll" target="build" />
 		<file src="runtimes\win10-x64\native\*.dll" target="ref\native" />
 	</files>
diff --git a/src/Sockets.cpp b/src/Sockets.cpp
index 9b2bb2e..0049ba4 100644
--- a/src/Sockets.cpp
+++ b/src/Sockets.cpp
@@ -606,6 +606,30 @@ int zts_udp_client(const char* remote_ipstr)
     return fd;
 }
 
+int zts_get_last_socket_error(int fd)
+{
+    int optval = 0;
+    zts_socklen_t optlen = sizeof(optval);
+    int err = ZTS_ERR_OK;
+    if ((err = zts_bsd_getsockopt(fd, ZTS_SOL_SOCKET, ZTS_SO_ERROR, &optval, &optlen)) < 0) {
+        return err;
+    }
+    return optval;
+}
+
+size_t zts_get_data_available(int fd)
+{
+    if (! transport_ok()) {
+        return ZTS_ERR_SERVICE;
+    }
+    int err = ZTS_ERR_OK;
+    size_t bytes_available = 0;
+    if ((err = zts_bsd_ioctl(fd, ZTS_FIONREAD, &bytes_available)) < 0) {
+        return err;
+    }
+    return bytes_available;
+}
+
 int zts_set_no_delay(int fd, int enabled)
 {
     if (! transport_ok()) {
diff --git a/src/bindings/csharp/CSharpSockets.cxx b/src/bindings/csharp/CSharpSockets.cxx
index 5ba3765..2baf66b 100644
--- a/src/bindings/csharp/CSharpSockets.cxx
+++ b/src/bindings/csharp/CSharpSockets.cxx
@@ -398,6 +398,11 @@ SWIGINTERN void SWIG_CSharpException(int code, const char* msg)
 extern "C" {
 #endif
 
+SWIGEXPORT int SWIGSTDCALL CSharp_zts_errno_get()
+{
+    return zts_errno;
+}
+
 #ifndef ZTS_DISABLE_CENTRAL_API
 
 SWIGEXPORT int SWIGSTDCALL CSharp_zts_central_set_access_mode(char jarg1)
@@ -1574,6 +1579,11 @@ SWIGEXPORT int SWIGSTDCALL CSharp_zts_bsd_shutdown(int jarg1, int jarg2)
     return jresult;
 }
 
+SWIGEXPORT size_t SWIGSTDCALL CSharp_zts_get_data_available(int fd)
+{
+    return zts_get_data_available(fd);
+}
+
 SWIGEXPORT int SWIGSTDCALL CSharp_zts_set_no_delay(int jarg1, int jarg2)
 {
     int jresult;
diff --git a/src/bindings/csharp/NetworkStream.cs b/src/bindings/csharp/NetworkStream.cs
new file mode 100644
index 0000000..2b87e6c
--- /dev/null
+++ b/src/bindings/csharp/NetworkStream.cs
@@ -0,0 +1,372 @@
+/*
+ * Copyright (c)2013-2021 ZeroTier, Inc.
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file in the project's root directory.
+ *
+ * Change Date: 2026-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2.0 of the Apache License.
+ */
+/****/
+
+using System;
+using System.Threading;
+using System.IO;
+using System.Runtime.InteropServices;
+using System.Net.Sockets;
+
+using ZeroTier;
+
+namespace ZeroTier.Sockets
+{
+    public class NetworkStream : Stream {
+        private ZeroTier.Sockets.Socket _streamSocket;
+
+        private bool _isReadable;
+        private bool _isWriteable;
+        private bool _ownsSocket;
+        private volatile bool _isDisposed = false;
+
+        internal NetworkStream()
+        {
+            _ownsSocket = true;
+        }
+
+        public NetworkStream(ZeroTier.Sockets.Socket socket)
+        {
+            if (socket == null) {
+                throw new ArgumentNullException("socket");
+            }
+            InitNetworkStream(socket, FileAccess.ReadWrite);
+        }
+
+        public NetworkStream(ZeroTier.Sockets.Socket socket, bool ownsSocket)
+        {
+            if (socket == null) {
+                throw new ArgumentNullException("socket");
+            }
+            InitNetworkStream(socket, FileAccess.ReadWrite);
+            _ownsSocket = ownsSocket;
+        }
+
+        public NetworkStream(ZeroTier.Sockets.Socket socket, FileAccess accessMode)
+        {
+            if (socket == null) {
+                throw new ArgumentNullException("socket");
+            }
+            InitNetworkStream(socket, accessMode);
+        }
+
+        public NetworkStream(ZeroTier.Sockets.Socket socket, FileAccess accessMode, bool ownsSocket)
+        {
+            if (socket == null) {
+                throw new ArgumentNullException("socket");
+            }
+            InitNetworkStream(socket, accessMode);
+            _ownsSocket = ownsSocket;
+        }
+
+        internal NetworkStream(NetworkStream networkStream, bool ownsSocket)
+        {
+            ZeroTier.Sockets.Socket socket = networkStream.Socket;
+            if (socket == null) {
+                throw new ArgumentNullException("networkStream");
+            }
+            InitNetworkStream(socket, FileAccess.ReadWrite);
+            _ownsSocket = ownsSocket;
+        }
+
+        protected ZeroTier.Sockets.Socket Socket
+        {
+            get {
+                return _streamSocket;
+            }
+        }
+
+        internal void ConvertToNotSocketOwner()
+        {
+            _ownsSocket = false;
+            GC.SuppressFinalize(this);
+        }
+
+        public override int ReadTimeout
+        {
+            get {
+                return _streamSocket.ReceiveTimeout;
+            }
+            set {
+                if (value <= 0) {
+                    throw new ArgumentOutOfRangeException("Timeout value must be greater than zero");
+                }
+                _streamSocket.ReceiveTimeout = value;
+            }
+        }
+
+        public override int WriteTimeout
+        {
+            get {
+                return _streamSocket.SendTimeout;
+            }
+            set {
+                if (value <= 0) {
+                    throw new ArgumentOutOfRangeException("Timeout value must be greater than zero");
+                }
+                _streamSocket.SendTimeout = value;
+            }
+        }
+
+        protected bool Readable
+        {
+            get {
+                return _isReadable;
+            }
+            set {
+                _isReadable = value;
+            }
+        }
+
+        protected bool Writeable
+        {
+            get {
+                return _isWriteable;
+            }
+            set {
+                _isWriteable = value;
+            }
+        }
+
+        public override bool CanRead
+        {
+            get {
+                return _isReadable;
+            }
+        }
+
+        public override bool CanSeek
+        {
+            get {
+                return false;
+            }
+        }
+
+        public override bool CanWrite
+        {
+            get {
+                return _isWriteable;
+            }
+        }
+
+        public override bool CanTimeout
+        {
+            get {
+                return true;
+            }
+        }
+
+        public virtual bool DataAvailable
+        {
+            get {
+                if (_streamSocket == null) {
+                    throw new IOException("ZeroTier socket is null");
+                }
+                if (_isDisposed) {
+                    throw new ObjectDisposedException("ZeroTier.Sockets.Socket");
+                }
+                return _streamSocket.Available != 0;
+            }
+        }
+
+        internal void InitNetworkStream(ZeroTier.Sockets.Socket socket, FileAccess accessMode)
+        {
+            if (! socket.Connected) {
+                throw new IOException("ZeroTier socket must be connected");
+            }
+            if (! socket.Blocking) {
+                throw new IOException("ZeroTier socket must be in blocking mode");
+            }
+            if (socket.SocketType != SocketType.Stream) {
+                throw new IOException("ZeroTier socket must by stream type");
+            }
+
+            _streamSocket = socket;
+
+            switch (accessMode) {
+                case FileAccess.Write:
+                    _isWriteable = true;
+                    break;
+                case FileAccess.Read:
+                    _isReadable = true;
+                    break;
+                case FileAccess.ReadWrite:
+                default:
+                    _isReadable = true;
+                    _isWriteable = true;
+                    break;
+            }
+        }
+
+        public override int Read([In, Out] byte[] buffer, int offset, int size)
+        {
+            bool canRead = CanRead;
+            if (_isDisposed) {
+                throw new ObjectDisposedException("ZeroTier.Sockets.Socket");
+            }
+            if (! canRead) {
+                throw new InvalidOperationException("Cannot read from ZeroTier socket");
+            }
+
+            if (buffer == null) {
+                throw new ArgumentNullException("buffer");
+            }
+            if (offset < 0 || offset > buffer.Length) {
+                throw new ArgumentOutOfRangeException("offset");
+            }
+            if (size < 0 || size > buffer.Length - offset) {
+                throw new ArgumentOutOfRangeException("size");
+            }
+
+            if (_streamSocket == null) {
+                throw new IOException("ZeroTier socket is null");
+            }
+
+            try {
+                int bytesTransferred = _streamSocket.Receive(buffer, offset, size, 0);
+                return bytesTransferred;
+            }
+            catch (Exception exception) {
+                throw new IOException("Cannot read from ZeroTier socket", exception);
+            }
+        }
+
+        public override void Write(byte[] buffer, int offset, int size)
+        {
+            bool canWrite = CanWrite;
+            if (_isDisposed) {
+                throw new ObjectDisposedException("ZeroTier.Sockets.Socket");
+            }
+            if (! canWrite) {
+                throw new InvalidOperationException("Cannot write to ZeroTier socket");
+            }
+            if (buffer == null) {
+                throw new ArgumentNullException("buffer");
+            }
+            if (offset < 0 || offset > buffer.Length) {
+                throw new ArgumentOutOfRangeException("offset");
+            }
+            if (size < 0 || size > buffer.Length - offset) {
+                throw new ArgumentOutOfRangeException("size");
+            }
+            if (_streamSocket == null) {
+                throw new IOException("ZeroTier socket is null");
+            }
+
+            try {
+                _streamSocket.Send(buffer, offset, size, SocketFlags.None);
+            }
+            catch (Exception exception) {
+                throw new IOException("Cannot write to ZeroTier socket", exception);
+            }
+        }
+
+        internal bool Poll(int microSeconds, SelectMode mode)
+        {
+            if (_streamSocket == null) {
+                throw new IOException("ZeroTier socket is null");
+            }
+            if (_isDisposed) {
+                throw new ObjectDisposedException("ZeroTier.Sockets.Socket");
+            }
+            return _streamSocket.Poll(microSeconds, mode);
+        }
+
+        internal bool PollRead()
+        {
+            if (_streamSocket == null) {
+                return false;
+            }
+            if (_isDisposed) {
+                return false;
+            }
+            return _streamSocket.Poll(0, SelectMode.SelectRead);
+        }
+
+        public override void Flush()
+        {
+            // Not applicable
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotSupportedException("Not supported");
+        }
+
+        public override long Length
+        {
+            get {
+                throw new NotSupportedException("Not supported");
+            }
+        }
+
+        public override long Position
+        {
+            get {
+                throw new NotSupportedException("Not supported");
+            }
+
+            set {
+                throw new NotSupportedException("Not supported");
+            }
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotSupportedException("Not supported");
+        }
+
+        public void Close(int timeout)
+        {
+            if (timeout < 0) {
+                throw new ArgumentOutOfRangeException("Timeout value must be greater than zero");
+            }
+            _streamSocket.Close(timeout);
+        }
+
+        internal bool Connected
+        {
+            get {
+                if (! _isDisposed && _streamSocket != null && _streamSocket.Connected) {
+                    return true;
+                }
+                else {
+                    return false;
+                }
+            }
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            bool cleanedUp = _isDisposed;
+            _isDisposed = true;
+            if (! cleanedUp && disposing) {
+                if (_streamSocket != null) {
+                    _isWriteable = false;
+                    _isReadable = false;
+                    if (_ownsSocket) {
+                        if (_streamSocket != null) {
+                            _streamSocket.Shutdown(SocketShutdown.Both);
+                            _streamSocket.Close();
+                        }
+                    }
+                }
+            }
+            base.Dispose(disposing);
+        }
+
+        ~NetworkStream()
+        {
+            Dispose(false);
+        }
+    }
+}
diff --git a/src/bindings/csharp/Socket.cs b/src/bindings/csharp/Socket.cs
index ea6d49e..89a4d6a 100644
--- a/src/bindings/csharp/Socket.cs
+++ b/src/bindings/csharp/Socket.cs
@@ -230,6 +230,12 @@ namespace ZeroTier.Sockets
 
         public void Close()
         {
+            Close(0);
+        }
+
+        public void Close(int timeout)
+        {
+            // TODO: Timeout needs to be implemented
             if (_isClosed) {
                 throw new ObjectDisposedException("Socket has already been closed");
             }
@@ -291,21 +297,10 @@ namespace ZeroTier.Sockets
 
         public Int32 Send(Byte[] buffer)
         {
-            if (_isClosed) {
-                throw new ObjectDisposedException("Socket has been closed");
-            }
-            if (_fd < 0) {
-                throw new ZeroTier.Sockets.SocketException((int)ZeroTier.Constants.ERR_SOCKET);
-            }
-            if (buffer == null) {
-                throw new ArgumentNullException("buffer");
-            }
-            int flags = 0;
-            IntPtr bufferPtr = Marshal.UnsafeAddrOfPinnedArrayElement(buffer, 0);
-            return zts_bsd_send(_fd, bufferPtr, (uint)Buffer.ByteLength(buffer), (int)flags);
+            return Send(buffer, 0, buffer != null ? buffer.Length : 0, SocketFlags.None);
         }
 
-        public Int32 Receive(Byte[] buffer)
+        public Int32 Send(Byte[] buffer, int offset, int size, SocketFlags socketFlags)
         {
             if (_isClosed) {
                 throw new ObjectDisposedException("Socket has been closed");
@@ -316,9 +311,49 @@ namespace ZeroTier.Sockets
             if (buffer == null) {
                 throw new ArgumentNullException("buffer");
             }
+            if (size < 0 || size > buffer.Length - offset) {
+                throw new ArgumentOutOfRangeException("size");
+            }
+            if (offset < 0 || offset > buffer.Length) {
+                throw new ArgumentOutOfRangeException("offset");
+            }
             int flags = 0;
             IntPtr bufferPtr = Marshal.UnsafeAddrOfPinnedArrayElement(buffer, 0);
-            return zts_bsd_recv(_fd, bufferPtr, (uint)Buffer.ByteLength(buffer), (int)flags);
+            return zts_bsd_send(_fd, bufferPtr + offset, (uint)Buffer.ByteLength(buffer), (int)flags);
+        }
+
+        public int Available
+        {
+            get {
+                return zts_get_data_available(_fd);
+            }
+        }
+
+        public Int32 Receive(Byte[] buffer)
+        {
+            return Receive(buffer, 0, buffer != null ? buffer.Length : 0, SocketFlags.None);
+        }
+
+        public Int32 Receive(byte[] buffer, int offset, int size, SocketFlags socketFlags)
+        {
+            if (_isClosed) {
+                throw new ObjectDisposedException("Socket has been closed");
+            }
+            if (_fd < 0) {
+                throw new ZeroTier.Sockets.SocketException((int)ZeroTier.Constants.ERR_SOCKET);
+            }
+            if (buffer == null) {
+                throw new ArgumentNullException("buffer");
+            }
+            if (size < 0 || size > buffer.Length - offset) {
+                throw new ArgumentOutOfRangeException("size");
+            }
+            if (offset < 0 || offset > buffer.Length) {
+                throw new ArgumentOutOfRangeException("offset");
+            }
+            int flags = 0;
+            IntPtr bufferPtr = Marshal.UnsafeAddrOfPinnedArrayElement(buffer, 0);
+            return zts_bsd_recv(_fd, bufferPtr + offset, (uint)Buffer.ByteLength(buffer), (int)flags);
         }
 
         public int ReceiveTimeout
@@ -579,6 +614,9 @@ namespace ZeroTier.Sockets
         [DllImport("libzt", EntryPoint = "CSharp_zts_bsd_shutdown")]
         static extern int zts_bsd_shutdown(int arg1, int arg2);
 
+        [DllImport("libzt", EntryPoint = "CSharp_zts_get_data_available")]
+        static extern int zts_get_data_available(int fd);
+
         [DllImport("libzt", EntryPoint = "CSharp_zts_set_no_delay")]
         static extern int zts_set_no_delay(int fd, int enabled);
 
diff --git a/test/selftest.c b/test/selftest.c
index f4a634e..ce9eafd 100644
--- a/test/selftest.c
+++ b/test/selftest.c
@@ -1146,6 +1146,15 @@ void test_server_socket_usage(uint16_t port4, uint16_t port6)
     // Read message
 
     memset(dstbuf, 0, buflen);
+
+    // Test zts_get_data_available
+    while (1) {
+        int av = zts_get_data_available(acc4);
+        zts_util_delay(50);
+        if (av > 0) {
+            break;
+        }
+    }
     bytes_read = zts_bsd_read(acc4, dstbuf, buflen);
     DEBUG_INFO("server4: read (%d) bytes", bytes_read);
     assert(bytes_read == msglen && zts_errno == 0);