diff --git a/Tutorials/EchoClient/App.config b/Tutorials/EchoClient/App.config
new file mode 100644
index 0000000..d740e88
--- /dev/null
+++ b/Tutorials/EchoClient/App.config
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<configuration>
+    <startup> 
+        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
+    </startup>
+</configuration>
\ No newline at end of file
diff --git a/Tutorials/EchoClient/ClientSimpleTcp.cs b/Tutorials/EchoClient/ClientSimpleTcp.cs
new file mode 100644
index 0000000..62fa8fe
--- /dev/null
+++ b/Tutorials/EchoClient/ClientSimpleTcp.cs
@@ -0,0 +1,93 @@
+using System;
+using System.Net.Sockets;
+using System.Net;
+
+namespace csharp_test_client
+{
+    public class ClientSimpleTcp
+    {
+        public Socket Sock = null;   
+        public string LatestErrorMsg;
+        
+
+        //소켓연결        
+        public bool Connect(string ip, int port)
+        {
+            try
+            {
+                IPAddress serverIP = IPAddress.Parse(ip);
+                int serverPort = port;
+
+                Sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                Sock.Connect(new IPEndPoint(serverIP, serverPort));
+
+                if (Sock == null || Sock.Connected == false)
+                {
+                    return false;
+                }
+
+                return true;
+            }
+            catch (Exception ex)
+            {
+                LatestErrorMsg = ex.Message;
+                return false;
+            }
+        }
+
+        public Tuple<int,byte[]> Receive()
+        {
+
+            try
+            {
+                byte[] ReadBuffer = new byte[2048];
+                var nRecv = Sock.Receive(ReadBuffer, 0, ReadBuffer.Length, SocketFlags.None);
+
+                if (nRecv == 0)
+                {
+                    return null;
+                }
+
+                return Tuple.Create(nRecv,ReadBuffer);
+            }
+            catch (SocketException se)
+            {
+                LatestErrorMsg = se.Message;
+            }
+
+            return null;
+        }
+
+        //스트림에 쓰기
+        public void Send(byte[] sendData)
+        {
+            try
+            {
+                if (Sock != null && Sock.Connected) //연결상태 유무 확인
+                {
+                    Sock.Send(sendData, 0, sendData.Length, SocketFlags.None);
+                }
+                else
+                {
+                    LatestErrorMsg = "먼저 채팅서버에 접속하세요!";
+                }
+            }
+            catch (SocketException se)
+            {
+                LatestErrorMsg = se.Message;
+            }
+        }
+
+        //소켓과 스트림 닫기
+        public void Close()
+        {
+            if (Sock != null && Sock.Connected)
+            {
+                //Sock.Shutdown(SocketShutdown.Both);
+                Sock.Close();
+            }
+        }
+
+        public bool IsConnected() { return (Sock != null && Sock.Connected) ? true : false; }
+    }
+}
diff --git a/Tutorials/EchoClient/DevLog.cs b/Tutorials/EchoClient/DevLog.cs
new file mode 100644
index 0000000..4d45fbe
--- /dev/null
+++ b/Tutorials/EchoClient/DevLog.cs
@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using System.Runtime.CompilerServices;
+using System.Threading;
+
+namespace csharp_test_client
+{
+    public class DevLog
+    {
+        static System.Collections.Concurrent.ConcurrentQueue<string> logMsgQueue = new System.Collections.Concurrent.ConcurrentQueue<string>();
+
+        static Int64 출력가능_로그레벨 = (Int64)LOG_LEVEL.TRACE;
+
+        
+
+        static public void Init(LOG_LEVEL logLevel)
+        {
+            ChangeLogLevel(logLevel);
+        }
+
+        static public void ChangeLogLevel(LOG_LEVEL logLevel)
+        {
+            Interlocked.Exchange(ref 출력가능_로그레벨, (int)logLevel);
+        }
+
+        public static LOG_LEVEL CurrentLogLevel()
+        {
+            var curLogLevel = (LOG_LEVEL)Interlocked.Read(ref 출력가능_로그레벨);
+            return curLogLevel;
+        }
+
+        static public void Write(string msg, LOG_LEVEL logLevel = LOG_LEVEL.TRACE,
+                                [CallerFilePath] string fileName = "",
+                                [CallerMemberName] string methodName = "",
+                                [CallerLineNumber] int lineNumber = 0)
+        {
+            if (CurrentLogLevel() <= logLevel)
+            {
+                logMsgQueue.Enqueue(string.Format("{0}:{1}| {2}", DateTime.Now, methodName, msg));
+            }
+        }
+
+        static public bool GetLog(out string msg)
+        {
+            if (logMsgQueue.TryDequeue(out msg))
+            {
+                return true;
+            }
+
+            return false;
+        }
+        
+    }
+
+
+    public enum LOG_LEVEL
+    {
+        TRACE,
+        DEBUG,
+        INFO,
+        WARN,
+        ERROR,
+        DISABLE
+    }
+}
diff --git a/Tutorials/EchoClient/Packet.cs b/Tutorials/EchoClient/Packet.cs
new file mode 100644
index 0000000..72f42dc
--- /dev/null
+++ b/Tutorials/EchoClient/Packet.cs
@@ -0,0 +1,260 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace csharp_test_client
+{
+    struct PacketData
+    {
+        public Int16 DataSize;
+        public Int16 PacketID;
+        public SByte Type;
+        public byte[] BodyData;
+    }
+
+    public class PacketDump
+    {
+        public static string Bytes(byte[] byteArr)
+        {
+            StringBuilder sb = new StringBuilder("[");
+            for (int i = 0; i < byteArr.Length; ++i)
+            {
+                sb.Append(byteArr[i] + " ");
+            }
+            sb.Append("]");
+            return sb.ToString();
+        }
+    }
+    
+
+    public class ErrorNtfPacket
+    {
+        public ERROR_CODE Error;
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            Error = (ERROR_CODE)BitConverter.ToInt16(bodyData, 0);
+            return true;
+        }
+    }
+    
+
+    public class LoginReqPacket
+    {
+        byte[] UserID = new byte[PacketDef.MAX_USER_ID_BYTE_LENGTH];
+        byte[] UserPW = new byte[PacketDef.MAX_USER_PW_BYTE_LENGTH];
+
+        public void SetValue(string userID, string userPW)
+        {
+            Encoding.UTF8.GetBytes(userID).CopyTo(UserID, 0);
+            Encoding.UTF8.GetBytes(userPW).CopyTo(UserPW, 0);
+        }
+
+        public byte[] ToBytes()
+        {
+            List<byte> dataSource = new List<byte>();
+            dataSource.AddRange(UserID);
+            dataSource.AddRange(UserPW);
+            return dataSource.ToArray();
+        }
+    }
+
+    public class LoginResPacket
+    {
+        public Int16 Result;
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            Result = BitConverter.ToInt16(bodyData, 0);
+            return true;
+        }
+    }
+
+
+    public class RoomEnterReqPacket
+    {
+        int RoomNumber;
+        public void SetValue(int roomNumber)
+        {
+            RoomNumber = roomNumber;
+        }
+
+        public byte[] ToBytes()
+        {
+            List<byte> dataSource = new List<byte>();
+            dataSource.AddRange(BitConverter.GetBytes(RoomNumber));
+            return dataSource.ToArray();
+        }
+    }
+
+    public class RoomEnterResPacket
+    {
+        public Int16 Result;
+        public Int64 RoomUserUniqueId;
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            Result = BitConverter.ToInt16(bodyData, 0);
+            RoomUserUniqueId = BitConverter.ToInt64(bodyData, 2);
+            return true;
+        }
+    }
+
+    public class RoomUserListNtfPacket
+    {
+        public int UserCount = 0;
+        public List<Int64> UserUniqueIdList = new List<Int64>();
+        public List<string> UserIDList = new List<string>();
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            var readPos = 0;
+            var userCount = (SByte)bodyData[readPos];
+            ++readPos;
+
+            for (int i = 0; i < userCount; ++i)
+            {
+                var uniqeudId = BitConverter.ToInt64(bodyData, readPos);
+                readPos += 8;
+
+                var idlen = (SByte)bodyData[readPos];
+                ++readPos;
+
+                var id = Encoding.UTF8.GetString(bodyData, readPos, idlen);
+                readPos += idlen;
+
+                UserUniqueIdList.Add(uniqeudId);
+                UserIDList.Add(id);
+            }
+
+            UserCount = userCount;
+            return true;
+        }
+    }
+
+    public class RoomNewUserNtfPacket
+    {
+        public Int64 UserUniqueId;
+        public string UserID;
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            var readPos = 0;
+
+            UserUniqueId = BitConverter.ToInt64(bodyData, readPos);
+            readPos += 8;
+
+            var idlen = (SByte)bodyData[readPos];
+            ++readPos;
+
+            UserID = Encoding.UTF8.GetString(bodyData, readPos, idlen);
+            readPos += idlen;
+
+            return true;
+        }
+    }
+
+
+    public class RoomChatReqPacket
+    {
+        Int16 MsgLen;
+        byte[] Msg;//= new byte[PacketDef.MAX_USER_ID_BYTE_LENGTH];
+
+        public void SetValue(string message)
+        {
+            Msg = Encoding.UTF8.GetBytes(message);
+            MsgLen = (Int16)Msg.Length;
+        }
+
+        public byte[] ToBytes()
+        {
+            List<byte> dataSource = new List<byte>();
+            dataSource.AddRange(BitConverter.GetBytes(MsgLen));
+            dataSource.AddRange(Msg);
+            return dataSource.ToArray();
+        }
+    }
+
+    public class RoomChatResPacket
+    {
+        public Int16 Result;
+        
+        public bool FromBytes(byte[] bodyData)
+        {
+            Result = BitConverter.ToInt16(bodyData, 0);
+            return true;
+        }
+    }
+
+    public class RoomChatNtfPacket
+    {
+        public Int64 UserUniqueId;
+        public string Message;
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            UserUniqueId = BitConverter.ToInt64(bodyData, 0);
+
+            var msgLen = BitConverter.ToInt16(bodyData, 8);
+            byte[] messageTemp = new byte[msgLen];
+            Buffer.BlockCopy(bodyData, 8 + 2, messageTemp, 0, msgLen);
+            Message = Encoding.UTF8.GetString(messageTemp);
+            return true;
+        }
+    }
+
+
+     public class RoomLeaveResPacket
+    {
+        public Int16 Result;
+        
+        public bool FromBytes(byte[] bodyData)
+        {
+            Result = BitConverter.ToInt16(bodyData, 0);
+            return true;
+        }
+    }
+
+    public class RoomLeaveUserNtfPacket
+    {
+        public Int64 UserUniqueId;
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            UserUniqueId = BitConverter.ToInt64(bodyData, 0);
+            return true;
+        }
+    }
+
+
+    
+    public class RoomRelayNtfPacket
+    {
+        public Int64 UserUniqueId;
+        public byte[] RelayData;
+
+        public bool FromBytes(byte[] bodyData)
+        {
+            UserUniqueId = BitConverter.ToInt64(bodyData, 0);
+
+            var relayDataLen = bodyData.Length - 8;
+            RelayData = new byte[relayDataLen];
+            Buffer.BlockCopy(bodyData, 8, RelayData, 0, relayDataLen);
+            return true;
+        }
+    }
+
+
+    public class PingRequest
+    {
+        public Int16 PingNum;
+
+        public byte[] ToBytes()
+        {
+            return BitConverter.GetBytes(PingNum);
+        }
+
+    }
+}
diff --git a/Tutorials/EchoClient/PacketBufferManager.cs b/Tutorials/EchoClient/PacketBufferManager.cs
new file mode 100644
index 0000000..590be3f
--- /dev/null
+++ b/Tutorials/EchoClient/PacketBufferManager.cs
@@ -0,0 +1,103 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace csharp_test_client
+{
+    class PacketBufferManager
+    {
+        int BufferSize = 0;
+        int ReadPos = 0;
+        int WritePos = 0;
+
+        int HeaderSize = 0;
+        int MaxPacketSize = 0;
+        byte[] PacketData;
+        byte[] PacketDataTemp;
+
+        public bool Init(int size, int headerSize, int maxPacketSize)
+        {
+            if (size < (maxPacketSize * 2) || size < 1 || headerSize < 1 || maxPacketSize < 1)
+            {
+                return false;
+            }
+
+            BufferSize = size;
+            PacketData = new byte[size];
+            PacketDataTemp = new byte[size];
+            HeaderSize = headerSize;
+            MaxPacketSize = maxPacketSize;
+
+            return true;
+        }
+
+        public bool Write(byte[] data, int pos, int size)
+        {
+            if (data == null || (data.Length < (pos + size)))
+            {
+                return false;
+            }
+
+            var remainBufferSize = BufferSize - WritePos;
+
+            if (remainBufferSize < size)
+            {
+                return false;
+            }
+
+            Buffer.BlockCopy(data, pos, PacketData, WritePos, size);
+            WritePos += size;
+
+            if (NextFree() == false)
+            {
+                BufferRelocate();
+            }
+            return true;
+        }
+
+        public ArraySegment<byte> Read()
+        {
+            var enableReadSize = WritePos - ReadPos;
+
+            if (enableReadSize < HeaderSize)
+            {
+                return new ArraySegment<byte>();
+            }
+
+            var packetDataSize = BitConverter.ToInt16(PacketData, ReadPos);
+            if (enableReadSize < packetDataSize)
+            {
+                return new ArraySegment<byte>();
+            }
+
+            var completePacketData = new ArraySegment<byte>(PacketData, ReadPos, packetDataSize);
+            ReadPos += packetDataSize;
+            return completePacketData;
+        }
+
+        bool NextFree()
+        {
+            var enableWriteSize = BufferSize - WritePos;
+
+            if (enableWriteSize < MaxPacketSize)
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+        void BufferRelocate()
+        {
+            var enableReadSize = WritePos - ReadPos;
+
+            Buffer.BlockCopy(PacketData, ReadPos, PacketDataTemp, 0, enableReadSize);
+            Buffer.BlockCopy(PacketDataTemp, 0, PacketData, 0, enableReadSize);
+
+            ReadPos = 0;
+            WritePos = enableReadSize;
+        }
+    }
+}
diff --git a/Tutorials/EchoClient/PacketDefine.cs b/Tutorials/EchoClient/PacketDefine.cs
new file mode 100644
index 0000000..396078c
--- /dev/null
+++ b/Tutorials/EchoClient/PacketDefine.cs
@@ -0,0 +1,62 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace csharp_test_client
+{
+    class PacketDef
+    {
+        public const Int16 PACKET_HEADER_SIZE = 5;
+        public const int MAX_USER_ID_BYTE_LENGTH = 16;
+        public const int MAX_USER_PW_BYTE_LENGTH = 16;
+    }
+
+    public enum PACKET_ID : ushort
+    {
+        PACKET_ID_ECHO = 101,
+
+        // Ping(Heart-beat)
+        PACKET_ID_PING_REQ = 201,
+        PACKET_ID_PING_RES = 202,
+
+        PACKET_ID_ERROR_NTF = 203,
+
+
+        // 로그인
+        PACKET_ID_LOGIN_REQ = 701,
+        PACKET_ID_LOGIN_RES = 702,
+                
+
+        PACKET_ID_ROOM_ENTER_REQ = 721,
+        PACKET_ID_ROOM_ENTER_RES = 722,
+        PACKET_ID_ROOM_USER_LIST_NTF = 723,
+        PACKET_ID_ROOM_NEW_USER_NTF = 724,
+
+         PACKET_ID_ROOM_LEAVE_REQ = 726,
+         PACKET_ID_ROOM_LEAVE_RES = 727,
+         PACKET_ID_ROOM_LEAVE_USER_NTF = 728,
+
+         PACKET_ID_ROOM_CHAT_REQ = 731,
+         PACKET_ID_ROOM_CHAT_RES = 732,
+         PACKET_ID_ROOM_CHAT_NOTIFY = 733,
+
+         PACKET_ID_ROOM_RELAY_REQ = 741,
+         PACKET_ID_ROOM_RELAY_NTF = 742,
+    }
+
+
+    public enum ERROR_CODE : Int16
+    {
+        ERROR_NONE = 0,
+
+
+
+        ERROR_CODE_USER_MGR_INVALID_USER_UNIQUEID = 112,
+
+        ERROR_CODE_PUBLIC_CHANNEL_IN_USER = 114,
+
+        ERROR_CODE_PUBLIC_CHANNEL_INVALIDE_NUMBER = 115,
+    }
+}
diff --git a/Tutorials/EchoClient/PacketProcessForm.cs b/Tutorials/EchoClient/PacketProcessForm.cs
new file mode 100644
index 0000000..32bea27
--- /dev/null
+++ b/Tutorials/EchoClient/PacketProcessForm.cs
@@ -0,0 +1,167 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace csharp_test_client
+{
+    public partial class mainForm
+    {
+        Dictionary<PACKET_ID, Action<byte[]>> PacketFuncDic = new Dictionary<PACKET_ID, Action<byte[]>>();
+
+        void SetPacketHandler()
+        {
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ECHO, PacketProcess_Echo);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ERROR_NTF, PacketProcess_ErrorNotify);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_LOGIN_RES, PacketProcess_LoginResponse);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_ENTER_RES, PacketProcess_RoomEnterResponse);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_USER_LIST_NTF, PacketProcess_RoomUserListNotify);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_NEW_USER_NTF, PacketProcess_RoomNewUserNotify);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_LEAVE_RES, PacketProcess_RoomLeaveResponse);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_LEAVE_USER_NTF, PacketProcess_RoomLeaveUserNotify);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_CHAT_RES, PacketProcess_RoomChatResponse);            
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_CHAT_NOTIFY, PacketProcess_RoomChatNotify);
+            PacketFuncDic.Add(PACKET_ID.PACKET_ID_ROOM_RELAY_NTF, PacketProcess_RoomRelayNotify);
+        }
+
+        void PacketProcess(PacketData packet)
+        {
+            var packetType = (PACKET_ID)packet.PacketID;
+            //DevLog.Write("Packet Error:  PacketID:{packet.PacketID.ToString()},  Error: {(ERROR_CODE)packet.Result}");
+            //DevLog.Write("RawPacket: " + packet.PacketID.ToString() + ", " + PacketDump.Bytes(packet.BodyData));
+
+            if (PacketFuncDic.ContainsKey(packetType))
+            {
+                PacketFuncDic[packetType](packet.BodyData);
+            }
+            else
+            {
+                DevLog.Write("Unknown Packet Id: " + packet.PacketID.ToString());
+            }         
+        }
+
+        void PacketProcess_Echo(byte[] bodyData)
+        {
+            DevLog.Write($"Echo 받음:  {bodyData.Length}");
+        }
+
+        void PacketProcess_ErrorNotify(byte[] bodyData)
+        {
+            var notifyPkt = new ErrorNtfPacket();
+            notifyPkt.FromBytes(bodyData);
+
+            DevLog.Write($"에러 통보 받음:  {notifyPkt.Error}");
+        }
+
+
+        void PacketProcess_LoginResponse(byte[] bodyData)
+        {
+            var responsePkt = new LoginResPacket();
+            responsePkt.FromBytes(bodyData);
+
+            DevLog.Write($"로그인 결과:  {(ERROR_CODE)responsePkt.Result}");
+        }
+
+
+        void PacketProcess_RoomEnterResponse(byte[] bodyData)
+        {
+            var responsePkt = new RoomEnterResPacket();
+            responsePkt.FromBytes(bodyData);
+
+            DevLog.Write($"방 입장 결과:  {(ERROR_CODE)responsePkt.Result}");
+        }
+
+        void PacketProcess_RoomUserListNotify(byte[] bodyData)
+        {
+            var notifyPkt = new RoomUserListNtfPacket();
+            notifyPkt.FromBytes(bodyData);
+
+            for (int i = 0; i < notifyPkt.UserCount; ++i)
+            {
+                AddRoomUserList(notifyPkt.UserUniqueIdList[i], notifyPkt.UserIDList[i]);
+            }
+
+            DevLog.Write($"방의 기존 유저 리스트 받음");
+        }
+
+        void PacketProcess_RoomNewUserNotify(byte[] bodyData)
+        {
+            var notifyPkt = new RoomNewUserNtfPacket();
+            notifyPkt.FromBytes(bodyData);
+
+            AddRoomUserList(notifyPkt.UserUniqueId, notifyPkt.UserID);
+            
+            DevLog.Write($"방에 새로 들어온 유저 받음");
+        }
+
+
+        void PacketProcess_RoomLeaveResponse(byte[] bodyData)
+        {
+            var responsePkt = new RoomLeaveResPacket();
+            responsePkt.FromBytes(bodyData);
+
+            DevLog.Write($"방 나가기 결과:  {(ERROR_CODE)responsePkt.Result}");
+        }
+
+        void PacketProcess_RoomLeaveUserNotify(byte[] bodyData)
+        {
+            var notifyPkt = new RoomLeaveUserNtfPacket();
+            notifyPkt.FromBytes(bodyData);
+
+            RemoveRoomUserList(notifyPkt.UserUniqueId);
+
+            DevLog.Write($"방에서 나간 유저 받음");
+        }
+
+
+        void PacketProcess_RoomChatResponse(byte[] bodyData)
+        {
+            var responsePkt = new RoomChatResPacket();
+            responsePkt.FromBytes(bodyData);
+
+            var errorCode = (ERROR_CODE)responsePkt.Result;
+            var msg = $"방 채팅 요청 결과:  {(ERROR_CODE)responsePkt.Result}";
+            if (errorCode == ERROR_CODE.ERROR_NONE)
+            {
+                DevLog.Write(msg, LOG_LEVEL.ERROR);
+            }
+            else
+            {
+                AddRoomChatMessageList(0, msg);
+            }
+        }
+
+
+        void PacketProcess_RoomChatNotify(byte[] bodyData)
+        {
+            var responsePkt = new RoomChatNtfPacket();
+            responsePkt.FromBytes(bodyData);
+
+            AddRoomChatMessageList(responsePkt.UserUniqueId, responsePkt.Message);
+        }
+
+        void AddRoomChatMessageList(Int64 userUniqueId, string msgssage)
+        {
+            var msg = $"{userUniqueId}:  {msgssage}";
+
+            if (listBoxRoomChatMsg.Items.Count > 512)
+            {
+                listBoxRoomChatMsg.Items.Clear();
+            }
+
+            listBoxRoomChatMsg.Items.Add(msg);
+            listBoxRoomChatMsg.SelectedIndex = listBoxRoomChatMsg.Items.Count - 1;
+        }
+
+
+        void PacketProcess_RoomRelayNotify(byte[] bodyData)
+        {
+            var notifyPkt = new RoomRelayNtfPacket();
+            notifyPkt.FromBytes(bodyData);
+
+            var stringData = Encoding.UTF8.GetString(notifyPkt.RelayData);
+            DevLog.Write($"방에서 릴레이 받음. {notifyPkt.UserUniqueId} - {stringData}");
+        }
+    }
+}
diff --git a/Tutorials/EchoClient/Program.cs b/Tutorials/EchoClient/Program.cs
new file mode 100644
index 0000000..7b9e1ff
--- /dev/null
+++ b/Tutorials/EchoClient/Program.cs
@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.Versioning;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+
+namespace csharp_test_client
+{
+    [SupportedOSPlatform("windows10.0.177630")]
+    static class Program
+    {
+        /// <summary>
+        /// 해당 응용 프로그램의 주 진입점입니다.
+        /// </summary>
+        [STAThread]
+        static void Main()
+        {
+            Application.EnableVisualStyles();
+            Application.SetCompatibleTextRenderingDefault(false);
+            Application.Run(new mainForm());
+        }
+    }
+}
diff --git a/Tutorials/EchoClient/Properties/AssemblyInfo.cs b/Tutorials/EchoClient/Properties/AssemblyInfo.cs
new file mode 100644
index 0000000..d3e425d
--- /dev/null
+++ b/Tutorials/EchoClient/Properties/AssemblyInfo.cs
@@ -0,0 +1,36 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// 어셈블리에 대한 일반 정보는 다음 특성 집합을 통해 
+// 제어됩니다. 어셈블리와 관련된 정보를 수정하려면
+// 이러한 특성 값을 변경하세요.
+[assembly: AssemblyTitle("csharp_test_client")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("csharp_test_client")]
+[assembly: AssemblyCopyright("Copyright ©  2016")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// ComVisible을 false로 설정하면 이 어셈블리의 형식이 COM 구성 요소에 
+// 표시되지 않습니다.  COM에서 이 어셈블리의 형식에 액세스하려면 
+// 해당 형식에 대해 ComVisible 특성을 true로 설정하세요.
+[assembly: ComVisible(false)]
+
+// 이 프로젝트가 COM에 노출되는 경우 다음 GUID는 typelib의 ID를 나타냅니다.
+[assembly: Guid("9e4b5e72-4e76-4e22-90b0-e53275a99018")]
+
+// 어셈블리의 버전 정보는 다음 네 가지 값으로 구성됩니다.
+//
+//      주 버전
+//      부 버전 
+//      빌드 번호
+//      수정 버전
+//
+// 모든 값을 지정하거나 아래와 같이 '*'를 사용하여 빌드 번호 및 수정 번호가 자동으로 
+// 지정되도록 할 수 있습니다.
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]
diff --git a/Tutorials/EchoClient/Properties/Resources.Designer.cs b/Tutorials/EchoClient/Properties/Resources.Designer.cs
new file mode 100644
index 0000000..fbcd69d
--- /dev/null
+++ b/Tutorials/EchoClient/Properties/Resources.Designer.cs
@@ -0,0 +1,71 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     이 코드는 도구를 사용하여 생성되었습니다.
+//     런타임 버전:4.0.30319.42000
+//
+//     파일 내용을 변경하면 잘못된 동작이 발생할 수 있으며, 코드를 다시 생성하면
+//     이러한 변경 내용이 손실됩니다.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace csharp_test_client.Properties
+{
+
+
+    /// <summary>
+    ///   지역화된 문자열 등을 찾기 위한 강력한 형식의 리소스 클래스입니다.
+    /// </summary>
+    // 이 클래스는 ResGen 또는 Visual Studio와 같은 도구를 통해 StronglyTypedResourceBuilder
+    // 클래스에서 자동으로 생성되었습니다.
+    // 멤버를 추가하거나 제거하려면 .ResX 파일을 편집한 다음 /str 옵션을 사용하여
+    // ResGen을 다시 실행하거나 VS 프로젝트를 다시 빌드하십시오.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "4.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    internal class Resources
+    {
+
+        private static global::System.Resources.ResourceManager resourceMan;
+
+        private static global::System.Globalization.CultureInfo resourceCulture;
+
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal Resources()
+        {
+        }
+
+        /// <summary>
+        ///   이 클래스에서 사용하는 캐시된 ResourceManager 인스턴스를 반환합니다.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Resources.ResourceManager ResourceManager
+        {
+            get
+            {
+                if ((resourceMan == null))
+                {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("csharp_test_client.Properties.Resources", typeof(Resources).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+
+        /// <summary>
+        ///   이 강력한 형식의 리소스 클래스를 사용하여 모든 리소스 조회에 대해
+        ///   현재 스레드의 CurrentUICulture 속성을 재정의합니다.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Globalization.CultureInfo Culture
+        {
+            get
+            {
+                return resourceCulture;
+            }
+            set
+            {
+                resourceCulture = value;
+            }
+        }
+    }
+}
diff --git a/Tutorials/EchoClient/Properties/Resources.resx b/Tutorials/EchoClient/Properties/Resources.resx
new file mode 100644
index 0000000..ffecec8
--- /dev/null
+++ b/Tutorials/EchoClient/Properties/Resources.resx
@@ -0,0 +1,117 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+</root>
\ No newline at end of file
diff --git a/Tutorials/EchoClient/Properties/Settings.Designer.cs b/Tutorials/EchoClient/Properties/Settings.Designer.cs
new file mode 100644
index 0000000..aca6dcd
--- /dev/null
+++ b/Tutorials/EchoClient/Properties/Settings.Designer.cs
@@ -0,0 +1,30 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace csharp_test_client.Properties
+{
+
+
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator", "11.0.0.0")]
+    internal sealed partial class Settings : global::System.Configuration.ApplicationSettingsBase
+    {
+
+        private static Settings defaultInstance = ((Settings)(global::System.Configuration.ApplicationSettingsBase.Synchronized(new Settings())));
+
+        public static Settings Default
+        {
+            get
+            {
+                return defaultInstance;
+            }
+        }
+    }
+}
diff --git a/Tutorials/EchoClient/Properties/Settings.settings b/Tutorials/EchoClient/Properties/Settings.settings
new file mode 100644
index 0000000..abf36c5
--- /dev/null
+++ b/Tutorials/EchoClient/Properties/Settings.settings
@@ -0,0 +1,7 @@
+<?xml version='1.0' encoding='utf-8'?>
+<SettingsFile xmlns="http://schemas.microsoft.com/VisualStudio/2004/01/settings" CurrentProfile="(Default)">
+  <Profiles>
+    <Profile Name="(Default)" />
+  </Profiles>
+  <Settings />
+</SettingsFile>
diff --git a/Tutorials/EchoClient/csharp_test_client.csproj b/Tutorials/EchoClient/csharp_test_client.csproj
new file mode 100644
index 0000000..ba2a444
--- /dev/null
+++ b/Tutorials/EchoClient/csharp_test_client.csproj
@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net8.0-windows10.0.17763.0</TargetFramework>
+    <OutputType>WinExe</OutputType>
+    <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
+    <UseWindowsForms>true</UseWindowsForms>
+    <ImportWindowsDesktopTargets>true</ImportWindowsDesktopTargets>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <OutputPath>..\bin\</OutputPath>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
+    <PackageReference Include="Z.ExtensionMethods" Version="2.1.1" />
+    <PackageReference Include="Microsoft.DotNet.UpgradeAssistant.Extensions.Default.Analyzers" Version="0.4.421302">
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.Windows.Compatibility" Version="8.0.0" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/Tutorials/EchoClient/csharp_test_client.sln b/Tutorials/EchoClient/csharp_test_client.sln
new file mode 100644
index 0000000..8a34e3c
--- /dev/null
+++ b/Tutorials/EchoClient/csharp_test_client.sln
@@ -0,0 +1,22 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 14
+VisualStudioVersion = 14.0.25420.1
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "csharp_test_client", "csharp_test_client.csproj", "{9E4B5E72-4E76-4E22-90B0-E53275A99018}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{9E4B5E72-4E76-4E22-90B0-E53275A99018}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9E4B5E72-4E76-4E22-90B0-E53275A99018}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9E4B5E72-4E76-4E22-90B0-E53275A99018}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9E4B5E72-4E76-4E22-90B0-E53275A99018}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+EndGlobal
diff --git a/Tutorials/EchoClient/mainForm.Designer.cs b/Tutorials/EchoClient/mainForm.Designer.cs
new file mode 100644
index 0000000..48e4419
--- /dev/null
+++ b/Tutorials/EchoClient/mainForm.Designer.cs
@@ -0,0 +1,454 @@
+namespace csharp_test_client
+{
+    partial class mainForm
+    {
+        /// <summary>
+        /// 필수 디자이너 변수입니다.
+        /// </summary>
+        private System.ComponentModel.IContainer components = null;
+
+        /// <summary>
+        /// 사용 중인 모든 리소스를 정리합니다.
+        /// </summary>
+        /// <param name="disposing">관리되는 리소스를 삭제해야 하면 true이고, 그렇지 않으면 false입니다.</param>
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing && (components != null))
+            {
+                components.Dispose();
+            }
+            base.Dispose(disposing);
+        }
+
+        #region Windows Form 디자이너에서 생성한 코드
+
+        /// <summary>
+        /// 디자이너 지원에 필요한 메서드입니다. 
+        /// 이 메서드의 내용을 코드 편집기로 수정하지 마세요.
+        /// </summary>
+        private void InitializeComponent()
+        {
+            btnDisconnect = new System.Windows.Forms.Button();
+            btnConnect = new System.Windows.Forms.Button();
+            groupBox5 = new System.Windows.Forms.GroupBox();
+            textBoxPort = new System.Windows.Forms.TextBox();
+            label10 = new System.Windows.Forms.Label();
+            checkBoxLocalHostIP = new System.Windows.Forms.CheckBox();
+            textBoxIP = new System.Windows.Forms.TextBox();
+            label9 = new System.Windows.Forms.Label();
+            button1 = new System.Windows.Forms.Button();
+            textSendText = new System.Windows.Forms.TextBox();
+            labelStatus = new System.Windows.Forms.Label();
+            listBoxLog = new System.Windows.Forms.ListBox();
+            label1 = new System.Windows.Forms.Label();
+            textBoxUserID = new System.Windows.Forms.TextBox();
+            textBoxUserPW = new System.Windows.Forms.TextBox();
+            label2 = new System.Windows.Forms.Label();
+            button2 = new System.Windows.Forms.Button();
+            Room = new System.Windows.Forms.GroupBox();
+            textBoxRelay = new System.Windows.Forms.TextBox();
+            btnRoomRelay = new System.Windows.Forms.Button();
+            btnRoomChat = new System.Windows.Forms.Button();
+            textBoxRoomSendMsg = new System.Windows.Forms.TextBox();
+            listBoxRoomChatMsg = new System.Windows.Forms.ListBox();
+            label4 = new System.Windows.Forms.Label();
+            listBoxRoomUserList = new System.Windows.Forms.ListBox();
+            btn_RoomLeave = new System.Windows.Forms.Button();
+            btn_RoomEnter = new System.Windows.Forms.Button();
+            textBoxRoomNumber = new System.Windows.Forms.TextBox();
+            label3 = new System.Windows.Forms.Label();
+            groupBox5.SuspendLayout();
+            Room.SuspendLayout();
+            SuspendLayout();
+            // 
+            // btnDisconnect
+            // 
+            btnDisconnect.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            btnDisconnect.Location = new System.Drawing.Point(421, 55);
+            btnDisconnect.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            btnDisconnect.Name = "btnDisconnect";
+            btnDisconnect.Size = new System.Drawing.Size(88, 32);
+            btnDisconnect.TabIndex = 29;
+            btnDisconnect.Text = "접속 끊기";
+            btnDisconnect.UseVisualStyleBackColor = true;
+            btnDisconnect.Click += btnDisconnect_Click;
+            // 
+            // btnConnect
+            // 
+            btnConnect.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            btnConnect.Location = new System.Drawing.Point(420, 20);
+            btnConnect.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            btnConnect.Name = "btnConnect";
+            btnConnect.Size = new System.Drawing.Size(88, 32);
+            btnConnect.TabIndex = 28;
+            btnConnect.Text = "접속하기";
+            btnConnect.UseVisualStyleBackColor = true;
+            btnConnect.Click += btnConnect_Click;
+            // 
+            // groupBox5
+            // 
+            groupBox5.Controls.Add(textBoxPort);
+            groupBox5.Controls.Add(label10);
+            groupBox5.Controls.Add(checkBoxLocalHostIP);
+            groupBox5.Controls.Add(textBoxIP);
+            groupBox5.Controls.Add(label9);
+            groupBox5.Location = new System.Drawing.Point(12, 15);
+            groupBox5.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            groupBox5.Name = "groupBox5";
+            groupBox5.Padding = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            groupBox5.Size = new System.Drawing.Size(403, 65);
+            groupBox5.TabIndex = 27;
+            groupBox5.TabStop = false;
+            groupBox5.Text = "Socket 더미 클라이언트 설정";
+            // 
+            // textBoxPort
+            // 
+            textBoxPort.Location = new System.Drawing.Point(225, 25);
+            textBoxPort.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textBoxPort.MaxLength = 6;
+            textBoxPort.Name = "textBoxPort";
+            textBoxPort.Size = new System.Drawing.Size(51, 23);
+            textBoxPort.TabIndex = 18;
+            textBoxPort.Text = "32452";
+            textBoxPort.WordWrap = false;
+            // 
+            // label10
+            // 
+            label10.AutoSize = true;
+            label10.Location = new System.Drawing.Point(163, 30);
+            label10.Name = "label10";
+            label10.Size = new System.Drawing.Size(62, 15);
+            label10.TabIndex = 17;
+            label10.Text = "포트 번호:";
+            // 
+            // checkBoxLocalHostIP
+            // 
+            checkBoxLocalHostIP.AutoSize = true;
+            checkBoxLocalHostIP.Checked = true;
+            checkBoxLocalHostIP.CheckState = System.Windows.Forms.CheckState.Checked;
+            checkBoxLocalHostIP.Location = new System.Drawing.Point(285, 30);
+            checkBoxLocalHostIP.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            checkBoxLocalHostIP.Name = "checkBoxLocalHostIP";
+            checkBoxLocalHostIP.Size = new System.Drawing.Size(102, 19);
+            checkBoxLocalHostIP.TabIndex = 15;
+            checkBoxLocalHostIP.Text = "localhost 사용";
+            checkBoxLocalHostIP.UseVisualStyleBackColor = true;
+            // 
+            // textBoxIP
+            // 
+            textBoxIP.Location = new System.Drawing.Point(68, 24);
+            textBoxIP.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textBoxIP.MaxLength = 6;
+            textBoxIP.Name = "textBoxIP";
+            textBoxIP.Size = new System.Drawing.Size(87, 23);
+            textBoxIP.TabIndex = 11;
+            textBoxIP.Text = "0.0.0.0";
+            textBoxIP.WordWrap = false;
+            // 
+            // label9
+            // 
+            label9.AutoSize = true;
+            label9.Location = new System.Drawing.Point(6, 29);
+            label9.Name = "label9";
+            label9.Size = new System.Drawing.Size(62, 15);
+            label9.TabIndex = 10;
+            label9.Text = "서버 주소:";
+            // 
+            // button1
+            // 
+            button1.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            button1.Location = new System.Drawing.Point(319, 88);
+            button1.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            button1.Name = "button1";
+            button1.Size = new System.Drawing.Size(100, 32);
+            button1.TabIndex = 39;
+            button1.Text = "echo 보내기";
+            button1.UseVisualStyleBackColor = true;
+            button1.Click += button1_Click;
+            // 
+            // textSendText
+            // 
+            textSendText.Location = new System.Drawing.Point(12, 92);
+            textSendText.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textSendText.MaxLength = 32;
+            textSendText.Name = "textSendText";
+            textSendText.Size = new System.Drawing.Size(301, 23);
+            textSendText.TabIndex = 38;
+            textSendText.Text = "test1";
+            textSendText.WordWrap = false;
+            // 
+            // labelStatus
+            // 
+            labelStatus.AutoSize = true;
+            labelStatus.Location = new System.Drawing.Point(10, 719);
+            labelStatus.Name = "labelStatus";
+            labelStatus.Size = new System.Drawing.Size(112, 15);
+            labelStatus.TabIndex = 40;
+            labelStatus.Text = "서버 접속 상태: ???";
+            // 
+            // listBoxLog
+            // 
+            listBoxLog.FormattingEnabled = true;
+            listBoxLog.HorizontalScrollbar = true;
+            listBoxLog.ItemHeight = 15;
+            listBoxLog.Location = new System.Drawing.Point(10, 532);
+            listBoxLog.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            listBoxLog.Name = "listBoxLog";
+            listBoxLog.Size = new System.Drawing.Size(490, 169);
+            listBoxLog.TabIndex = 41;
+            // 
+            // label1
+            // 
+            label1.AutoSize = true;
+            label1.Location = new System.Drawing.Point(10, 153);
+            label1.Name = "label1";
+            label1.Size = new System.Drawing.Size(45, 15);
+            label1.TabIndex = 42;
+            label1.Text = "UserID:";
+            // 
+            // textBoxUserID
+            // 
+            textBoxUserID.Location = new System.Drawing.Point(62, 149);
+            textBoxUserID.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textBoxUserID.MaxLength = 6;
+            textBoxUserID.Name = "textBoxUserID";
+            textBoxUserID.Size = new System.Drawing.Size(87, 23);
+            textBoxUserID.TabIndex = 43;
+            textBoxUserID.Text = "jacking75";
+            textBoxUserID.WordWrap = false;
+            // 
+            // textBoxUserPW
+            // 
+            textBoxUserPW.Location = new System.Drawing.Point(220, 150);
+            textBoxUserPW.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textBoxUserPW.MaxLength = 6;
+            textBoxUserPW.Name = "textBoxUserPW";
+            textBoxUserPW.Size = new System.Drawing.Size(87, 23);
+            textBoxUserPW.TabIndex = 45;
+            textBoxUserPW.Text = "jacking75";
+            textBoxUserPW.WordWrap = false;
+            // 
+            // label2
+            // 
+            label2.AutoSize = true;
+            label2.Location = new System.Drawing.Point(158, 154);
+            label2.Name = "label2";
+            label2.Size = new System.Drawing.Size(53, 15);
+            label2.TabIndex = 44;
+            label2.Text = "PassWD:";
+            // 
+            // button2
+            // 
+            button2.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            button2.Location = new System.Drawing.Point(316, 144);
+            button2.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            button2.Name = "button2";
+            button2.Size = new System.Drawing.Size(100, 32);
+            button2.TabIndex = 46;
+            button2.Text = "Login";
+            button2.UseVisualStyleBackColor = true;
+            button2.Click += button2_Click;
+            // 
+            // Room
+            // 
+            Room.Controls.Add(textBoxRelay);
+            Room.Controls.Add(btnRoomRelay);
+            Room.Controls.Add(btnRoomChat);
+            Room.Controls.Add(textBoxRoomSendMsg);
+            Room.Controls.Add(listBoxRoomChatMsg);
+            Room.Controls.Add(label4);
+            Room.Controls.Add(listBoxRoomUserList);
+            Room.Controls.Add(btn_RoomLeave);
+            Room.Controls.Add(btn_RoomEnter);
+            Room.Controls.Add(textBoxRoomNumber);
+            Room.Controls.Add(label3);
+            Room.Location = new System.Drawing.Point(13, 213);
+            Room.Name = "Room";
+            Room.Size = new System.Drawing.Size(495, 312);
+            Room.TabIndex = 47;
+            Room.TabStop = false;
+            Room.Text = "Room";
+            // 
+            // textBoxRelay
+            // 
+            textBoxRelay.Location = new System.Drawing.Point(306, 30);
+            textBoxRelay.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textBoxRelay.MaxLength = 6;
+            textBoxRelay.Name = "textBoxRelay";
+            textBoxRelay.Size = new System.Drawing.Size(109, 23);
+            textBoxRelay.TabIndex = 55;
+            textBoxRelay.Text = "test";
+            textBoxRelay.WordWrap = false;
+            // 
+            // btnRoomRelay
+            // 
+            btnRoomRelay.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            btnRoomRelay.Location = new System.Drawing.Point(420, 25);
+            btnRoomRelay.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            btnRoomRelay.Name = "btnRoomRelay";
+            btnRoomRelay.Size = new System.Drawing.Size(66, 32);
+            btnRoomRelay.TabIndex = 54;
+            btnRoomRelay.Text = "Relay";
+            btnRoomRelay.UseVisualStyleBackColor = true;
+            btnRoomRelay.Click += btnRoomRelay_Click;
+            // 
+            // btnRoomChat
+            // 
+            btnRoomChat.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            btnRoomChat.Location = new System.Drawing.Point(437, 265);
+            btnRoomChat.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            btnRoomChat.Name = "btnRoomChat";
+            btnRoomChat.Size = new System.Drawing.Size(50, 32);
+            btnRoomChat.TabIndex = 53;
+            btnRoomChat.Text = "chat";
+            btnRoomChat.UseVisualStyleBackColor = true;
+            btnRoomChat.Click += btnRoomChat_Click;
+            // 
+            // textBoxRoomSendMsg
+            // 
+            textBoxRoomSendMsg.Location = new System.Drawing.Point(13, 269);
+            textBoxRoomSendMsg.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textBoxRoomSendMsg.MaxLength = 32;
+            textBoxRoomSendMsg.Name = "textBoxRoomSendMsg";
+            textBoxRoomSendMsg.Size = new System.Drawing.Size(419, 23);
+            textBoxRoomSendMsg.TabIndex = 52;
+            textBoxRoomSendMsg.Text = "test1";
+            textBoxRoomSendMsg.WordWrap = false;
+            // 
+            // listBoxRoomChatMsg
+            // 
+            listBoxRoomChatMsg.FormattingEnabled = true;
+            listBoxRoomChatMsg.ItemHeight = 15;
+            listBoxRoomChatMsg.Location = new System.Drawing.Point(144, 81);
+            listBoxRoomChatMsg.Name = "listBoxRoomChatMsg";
+            listBoxRoomChatMsg.Size = new System.Drawing.Size(343, 169);
+            listBoxRoomChatMsg.TabIndex = 51;
+            // 
+            // label4
+            // 
+            label4.AutoSize = true;
+            label4.Location = new System.Drawing.Point(10, 64);
+            label4.Name = "label4";
+            label4.Size = new System.Drawing.Size(55, 15);
+            label4.TabIndex = 50;
+            label4.Text = "User List:";
+            // 
+            // listBoxRoomUserList
+            // 
+            listBoxRoomUserList.FormattingEnabled = true;
+            listBoxRoomUserList.ItemHeight = 15;
+            listBoxRoomUserList.Location = new System.Drawing.Point(13, 82);
+            listBoxRoomUserList.Name = "listBoxRoomUserList";
+            listBoxRoomUserList.Size = new System.Drawing.Size(123, 169);
+            listBoxRoomUserList.TabIndex = 49;
+            // 
+            // btn_RoomLeave
+            // 
+            btn_RoomLeave.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            btn_RoomLeave.Location = new System.Drawing.Point(216, 24);
+            btn_RoomLeave.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            btn_RoomLeave.Name = "btn_RoomLeave";
+            btn_RoomLeave.Size = new System.Drawing.Size(66, 32);
+            btn_RoomLeave.TabIndex = 48;
+            btn_RoomLeave.Text = "Leave";
+            btn_RoomLeave.UseVisualStyleBackColor = true;
+            btn_RoomLeave.Click += btn_RoomLeave_Click;
+            // 
+            // btn_RoomEnter
+            // 
+            btn_RoomEnter.Font = new System.Drawing.Font("맑은 고딕", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, 129);
+            btn_RoomEnter.Location = new System.Drawing.Point(144, 23);
+            btn_RoomEnter.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            btn_RoomEnter.Name = "btn_RoomEnter";
+            btn_RoomEnter.Size = new System.Drawing.Size(66, 32);
+            btn_RoomEnter.TabIndex = 47;
+            btn_RoomEnter.Text = "Enter";
+            btn_RoomEnter.UseVisualStyleBackColor = true;
+            btn_RoomEnter.Click += btn_RoomEnter_Click;
+            // 
+            // textBoxRoomNumber
+            // 
+            textBoxRoomNumber.Location = new System.Drawing.Point(98, 25);
+            textBoxRoomNumber.Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            textBoxRoomNumber.MaxLength = 6;
+            textBoxRoomNumber.Name = "textBoxRoomNumber";
+            textBoxRoomNumber.Size = new System.Drawing.Size(38, 23);
+            textBoxRoomNumber.TabIndex = 44;
+            textBoxRoomNumber.Text = "0";
+            textBoxRoomNumber.WordWrap = false;
+            // 
+            // label3
+            // 
+            label3.AutoSize = true;
+            label3.Location = new System.Drawing.Point(5, 31);
+            label3.Name = "label3";
+            label3.Size = new System.Drawing.Size(90, 15);
+            label3.TabIndex = 43;
+            label3.Text = "Room Number:";
+            // 
+            // mainForm
+            // 
+            AutoScaleDimensions = new System.Drawing.SizeF(7F, 15F);
+            AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
+            ClientSize = new System.Drawing.Size(524, 751);
+            Controls.Add(Room);
+            Controls.Add(button2);
+            Controls.Add(textBoxUserPW);
+            Controls.Add(label2);
+            Controls.Add(textBoxUserID);
+            Controls.Add(label1);
+            Controls.Add(labelStatus);
+            Controls.Add(listBoxLog);
+            Controls.Add(button1);
+            Controls.Add(textSendText);
+            Controls.Add(btnDisconnect);
+            Controls.Add(btnConnect);
+            Controls.Add(groupBox5);
+            FormBorderStyle = System.Windows.Forms.FormBorderStyle.Fixed3D;
+            Margin = new System.Windows.Forms.Padding(3, 4, 3, 4);
+            Name = "mainForm";
+            Text = "네트워크 테스트 클라이언트";
+            FormClosing += mainForm_FormClosing;
+            Load += mainForm_Load;
+            groupBox5.ResumeLayout(false);
+            groupBox5.PerformLayout();
+            Room.ResumeLayout(false);
+            Room.PerformLayout();
+            ResumeLayout(false);
+            PerformLayout();
+        }
+
+        #endregion
+
+        private System.Windows.Forms.Button btnDisconnect;
+        private System.Windows.Forms.Button btnConnect;
+        private System.Windows.Forms.GroupBox groupBox5;
+        private System.Windows.Forms.TextBox textBoxPort;
+        private System.Windows.Forms.Label label10;
+        private System.Windows.Forms.CheckBox checkBoxLocalHostIP;
+        private System.Windows.Forms.TextBox textBoxIP;
+        private System.Windows.Forms.Label label9;
+        private System.Windows.Forms.Button button1;
+        private System.Windows.Forms.TextBox textSendText;
+        private System.Windows.Forms.Label labelStatus;
+        private System.Windows.Forms.ListBox listBoxLog;
+        private System.Windows.Forms.Label label1;
+        private System.Windows.Forms.TextBox textBoxUserID;
+        private System.Windows.Forms.TextBox textBoxUserPW;
+        private System.Windows.Forms.Label label2;
+        private System.Windows.Forms.Button button2;
+        private System.Windows.Forms.GroupBox Room;
+        private System.Windows.Forms.Button btn_RoomLeave;
+        private System.Windows.Forms.Button btn_RoomEnter;
+        private System.Windows.Forms.TextBox textBoxRoomNumber;
+        private System.Windows.Forms.Label label3;
+        private System.Windows.Forms.Button btnRoomChat;
+        private System.Windows.Forms.TextBox textBoxRoomSendMsg;
+        private System.Windows.Forms.ListBox listBoxRoomChatMsg;
+        private System.Windows.Forms.Label label4;
+        private System.Windows.Forms.ListBox listBoxRoomUserList;
+        private System.Windows.Forms.Button btnRoomRelay;
+        private System.Windows.Forms.TextBox textBoxRelay;
+    }
+}
+
diff --git a/Tutorials/EchoClient/mainForm.cs b/Tutorials/EchoClient/mainForm.cs
new file mode 100644
index 0000000..ca58439
--- /dev/null
+++ b/Tutorials/EchoClient/mainForm.cs
@@ -0,0 +1,376 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Data;
+using System.Drawing;
+using System.Linq;
+using System.Runtime.Versioning;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+
+namespace csharp_test_client
+{
+    [SupportedOSPlatform("windows10.0.177630")]
+    public partial class mainForm : Form
+    {
+        ClientSimpleTcp Network = new ClientSimpleTcp();
+
+        bool IsNetworkThreadRunning = false;
+        bool IsBackGroundProcessRunning = false;
+
+        System.Threading.Thread NetworkReadThread = null;
+        System.Threading.Thread NetworkSendThread = null;
+
+        PacketBufferManager PacketBuffer = new PacketBufferManager();
+        Queue<PacketData> RecvPacketQueue = new Queue<PacketData>();
+        Queue<byte[]> SendPacketQueue = new Queue<byte[]>();
+
+        System.Windows.Forms.Timer dispatcherUITimer = new();
+
+
+        public mainForm()
+        {
+            InitializeComponent();
+        }
+
+        private void mainForm_Load(object sender, EventArgs e)
+        {
+            PacketBuffer.Init((8096 * 10), PacketDef.PACKET_HEADER_SIZE, 1024);
+
+            IsNetworkThreadRunning = true;
+            NetworkReadThread = new System.Threading.Thread(this.NetworkReadProcess);
+            NetworkReadThread.Start();
+            NetworkSendThread = new System.Threading.Thread(this.NetworkSendProcess);
+            NetworkSendThread.Start();
+
+            IsBackGroundProcessRunning = true;
+            /*dispatcherUITimer = new System.Windows.Threading.DispatcherTimer();
+            dispatcherUITimer.Tick += new EventHandler(BackGroundProcess);
+            dispatcherUITimer.Interval = new TimeSpan(0, 0, 0, 0, 100);
+            dispatcherUITimer.Start();*/
+            dispatcherUITimer.Tick += new EventHandler(BackGroundProcess);
+            dispatcherUITimer.Interval = 100;
+            dispatcherUITimer.Start();
+
+            btnDisconnect.Enabled = false;
+
+            SetPacketHandler();
+            DevLog.Write("프로그램 시작 !!!", LOG_LEVEL.INFO);
+        }
+
+        private void mainForm_FormClosing(object sender, FormClosingEventArgs e)
+        {
+            IsNetworkThreadRunning = false;
+            IsBackGroundProcessRunning = false;
+
+            Network.Close();
+        }
+
+        private void btnConnect_Click(object sender, EventArgs e)
+        {
+            string address = textBoxIP.Text;
+
+            if (checkBoxLocalHostIP.Checked)
+            {
+                address = "127.0.0.1";
+            }
+
+            int port = Convert.ToInt32(textBoxPort.Text);
+
+            if (Network.Connect(address, port))
+            {
+                labelStatus.Text = string.Format("{0}. 서버에 접속 중", DateTime.Now);
+                btnConnect.Enabled = false;
+                btnDisconnect.Enabled = true;
+
+                DevLog.Write($"서버에 접속 중", LOG_LEVEL.INFO);
+            }
+            else
+            {
+                labelStatus.Text = string.Format("{0}. 서버에 접속 실패", DateTime.Now);
+            }
+        }
+
+        private void btnDisconnect_Click(object sender, EventArgs e)
+        {
+            SetDisconnectd();
+            Network.Close();
+        }
+
+        private void button1_Click(object sender, EventArgs e)
+        {
+            if (string.IsNullOrEmpty(textSendText.Text))
+            {
+                MessageBox.Show("보낼 텍스트를 입력하세요");
+                return;
+            }
+
+            var body = Encoding.UTF8.GetBytes(textSendText.Text);
+
+            PostSendPacket(PACKET_ID.PACKET_ID_ECHO, body);
+
+            DevLog.Write($"Echo 요청:  {textSendText.Text}, {body.Length}");
+        }
+
+
+
+        void NetworkReadProcess()
+        {
+            const Int16 PacketHeaderSize = PacketDef.PACKET_HEADER_SIZE;
+
+            while (IsNetworkThreadRunning)
+            {
+                if (Network.IsConnected() == false)
+                {
+                    System.Threading.Thread.Sleep(1);
+                    continue;
+                }
+
+                var recvData = Network.Receive();
+
+                if (recvData != null)
+                {
+                    PacketBuffer.Write(recvData.Item2, 0, recvData.Item1);
+
+                    while (true)
+                    {
+                        var data = PacketBuffer.Read();
+                        if (data.Count < 1)
+                        {
+                            break;
+                        }
+
+                        var packet = new PacketData();
+                        packet.DataSize = (short)(data.Count - PacketHeaderSize);
+                        packet.PacketID = BitConverter.ToInt16(data.Array, data.Offset + 2);
+                        packet.Type = (SByte)data.Array[(data.Offset + 4)];
+                        packet.BodyData = new byte[packet.DataSize];
+                        Buffer.BlockCopy(data.Array, (data.Offset + PacketHeaderSize), packet.BodyData, 0, (data.Count - PacketHeaderSize));
+                        lock (((System.Collections.ICollection)RecvPacketQueue).SyncRoot)
+                        {
+                            RecvPacketQueue.Enqueue(packet);
+                        }
+                    }
+                    //DevLog.Write($"받은 데이터: {recvData.Item2}", LOG_LEVEL.INFO);
+                }
+                else
+                {
+                    Network.Close();
+                    SetDisconnectd();
+                    DevLog.Write("서버와 접속 종료 !!!", LOG_LEVEL.INFO);
+                }
+            }
+        }
+
+        void NetworkSendProcess()
+        {
+            while (IsNetworkThreadRunning)
+            {
+                System.Threading.Thread.Sleep(1);
+
+                if (Network.IsConnected() == false)
+                {
+                    continue;
+                }
+
+                lock (((System.Collections.ICollection)SendPacketQueue).SyncRoot)
+                {
+                    if (SendPacketQueue.Count > 0)
+                    {
+                        var packet = SendPacketQueue.Dequeue();
+                        Network.Send(packet);
+                    }
+                }
+            }
+        }
+
+
+        void BackGroundProcess(object sender, EventArgs e)
+        {
+            ProcessLog();
+
+            try
+            {
+                var packet = new PacketData();
+
+                lock (((System.Collections.ICollection)RecvPacketQueue).SyncRoot)
+                {
+                    if (RecvPacketQueue.Count() > 0)
+                    {
+                        packet = RecvPacketQueue.Dequeue();
+                    }
+                }
+
+                if (packet.PacketID != 0)
+                {
+                    PacketProcess(packet);
+                }
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show(string.Format("ReadPacketQueueProcess. error:{0}", ex.Message));
+            }
+        }
+
+        private void ProcessLog()
+        {
+            // 너무 이 작업만 할 수 없으므로 일정 작업 이상을 하면 일단 패스한다.
+            int logWorkCount = 0;
+
+            while (IsBackGroundProcessRunning)
+            {
+                System.Threading.Thread.Sleep(1);
+
+                string msg;
+
+                if (DevLog.GetLog(out msg))
+                {
+                    ++logWorkCount;
+
+                    if (listBoxLog.Items.Count > 512)
+                    {
+                        listBoxLog.Items.Clear();
+                    }
+
+                    listBoxLog.Items.Add(msg);
+                    listBoxLog.SelectedIndex = listBoxLog.Items.Count - 1;
+                }
+                else
+                {
+                    break;
+                }
+
+                if (logWorkCount > 8)
+                {
+                    break;
+                }
+            }
+        }
+
+
+        public void SetDisconnectd()
+        {
+            if (btnConnect.Enabled == false)
+            {
+                btnConnect.Enabled = true;
+                btnDisconnect.Enabled = false;
+            }
+
+            SendPacketQueue.Clear();
+
+            listBoxRoomChatMsg.Items.Clear();
+            listBoxRoomUserList.Items.Clear();
+
+            labelStatus.Text = "서버 접속이 끊어짐";
+        }
+
+        public void PostSendPacket(PACKET_ID packetID, byte[] bodyData)
+        {
+            if (Network.IsConnected() == false)
+            {
+                DevLog.Write("서버 연결이 되어 있지 않습니다", LOG_LEVEL.ERROR);
+                return;
+            }
+
+            Int16 bodyDataSize = 0;
+            if (bodyData != null)
+            {
+                bodyDataSize = (Int16)bodyData.Length;
+            }
+            var packetSize = bodyDataSize + PacketDef.PACKET_HEADER_SIZE;
+
+            List<byte> dataSource = new List<byte>();
+            dataSource.AddRange(BitConverter.GetBytes((Int16)packetSize));
+            dataSource.AddRange(BitConverter.GetBytes((Int16)packetID));
+            dataSource.AddRange(new byte[] { (byte)0 });
+            
+            if (bodyData != null)
+            {
+                dataSource.AddRange(bodyData);
+            }
+           
+            SendPacketQueue.Enqueue(dataSource.ToArray());
+        }
+
+        void AddRoomUserList(Int64 userUniqueId, string userID)
+        {
+            var msg = $"{userUniqueId}: {userID}";
+            listBoxRoomUserList.Items.Add(msg);
+        }
+
+        void RemoveRoomUserList(Int64 userUniqueId)
+        {
+            object removeItem = null;
+
+            foreach( var user in listBoxRoomUserList.Items)
+            {
+                var items = user.ToString().Split(":");
+                if( items[0].ToInt64() == userUniqueId)
+                {
+                    removeItem = user;
+                    return;
+                }
+            }
+
+            if (removeItem != null)
+            {
+                listBoxRoomUserList.Items.Remove(removeItem);
+            }
+        }
+
+
+        // 로그인 요청
+        private void button2_Click(object sender, EventArgs e)
+        {
+            var loginReq = new LoginReqPacket();
+            loginReq.SetValue(textBoxUserID.Text, textBoxUserPW.Text);
+                    
+            PostSendPacket(PACKET_ID.PACKET_ID_LOGIN_REQ, loginReq.ToBytes());            
+            DevLog.Write($"로그인 요청:  {textBoxUserID.Text}, {textBoxUserPW.Text}");
+        }
+
+        private void btn_RoomEnter_Click(object sender, EventArgs e)
+        {
+            var requestPkt = new RoomEnterReqPacket();
+            requestPkt.SetValue(textBoxRoomNumber.Text.ToInt32());
+
+            PostSendPacket(PACKET_ID.PACKET_ID_ROOM_ENTER_REQ, requestPkt.ToBytes());
+            DevLog.Write($"방 입장 요청:  {textBoxRoomNumber.Text} 번");
+        }
+
+        private void btn_RoomLeave_Click(object sender, EventArgs e)
+        {
+            PostSendPacket(PACKET_ID.PACKET_ID_ROOM_LEAVE_REQ,  null);
+            DevLog.Write($"방 입장 요청:  {textBoxRoomNumber.Text} 번");
+        }
+
+        private void btnRoomChat_Click(object sender, EventArgs e)
+        {
+            if(textBoxRoomSendMsg.Text.IsEmpty())
+            {
+                MessageBox.Show("채팅 메시지를 입력하세요");
+                return;
+            }
+
+            var requestPkt = new RoomChatReqPacket();
+            requestPkt.SetValue(textBoxRoomSendMsg.Text);
+
+            PostSendPacket(PACKET_ID.PACKET_ID_ROOM_CHAT_REQ, requestPkt.ToBytes());
+            DevLog.Write($"방 채팅 요청");
+        }
+
+        private void btnRoomRelay_Click(object sender, EventArgs e)
+        {
+            if( textBoxRelay.Text.IsEmpty())
+            {
+                MessageBox.Show("릴레이 할 데이터가 없습니다");
+                return;
+            }
+            
+            var bodyData = Encoding.UTF8.GetBytes(textBoxRelay.Text);
+            PostSendPacket(PACKET_ID.PACKET_ID_ROOM_RELAY_REQ, bodyData);
+            DevLog.Write($"방 릴레이 요청");
+        }
+    }
+}
diff --git a/Tutorials/EchoClient/mainForm.resx b/Tutorials/EchoClient/mainForm.resx
new file mode 100644
index 0000000..b92c163
--- /dev/null
+++ b/Tutorials/EchoClient/mainForm.resx
@@ -0,0 +1,120 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!--
+    Microsoft ResX Schema 
+
+    Version 2.0
+
+    The primary goals of this format is to allow a simple XML format
+    that is mostly human readable. The generation and parsing of the
+    various data types are done through the TypeConverter classes
+    associated with the data types.
+
+    Example:
+
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+
+    There are any number of "resheader" rows that contain simple
+    name/value pairs.
+
+    Each data row contains a name, and value. The row also contains a
+    type or mimetype. Type corresponds to a .NET class that support
+    text/value conversion through the TypeConverter architecture.
+    Classes that don't support this are serialized and stored with the
+    mimetype set.
+
+    The mimetype is used for serialized objects, and tells the
+    ResXResourceReader how to depersist the object. This is currently not
+    extensible. For a given mimetype the value must be set accordingly:
+
+    Note - application/x-microsoft.net.object.binary.base64 is the format
+    that the ResXResourceWriter will generate, however the reader can
+    read any of the formats listed below.
+
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+</root>
\ No newline at end of file
diff --git a/Tutorials/PvPGameServer_Client/Packet.cs b/Tutorials/PvPGameServer_Client/Packet.cs
index 67ecc7c..1645f73 100644
--- a/Tutorials/PvPGameServer_Client/Packet.cs
+++ b/Tutorials/PvPGameServer_Client/Packet.cs
@@ -7,15 +7,7 @@
 using System.Threading.Tasks;
 
 namespace csharp_test_client
-{
-    struct PacketData
-    {
-        public Int16 DataSize;
-        public Int16 PacketID;
-        public SByte Type;
-        public byte[] BodyData;
-    }
-
+{    
     public struct MsgPackPacketHeadInfo
     {
         const int PacketHeaderMsgPackStartPos = 3;
diff --git a/Tutorials/PvPGameServer_Client/Program.cs b/Tutorials/PvPGameServer_Client/Program.cs
index a98e647..7b9e1ff 100644
--- a/Tutorials/PvPGameServer_Client/Program.cs
+++ b/Tutorials/PvPGameServer_Client/Program.cs
@@ -1,11 +1,13 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.Versioning;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 
 namespace csharp_test_client
 {
+    [SupportedOSPlatform("windows10.0.177630")]
     static class Program
     {
         /// <summary>
diff --git a/Tutorials/PvPGameServer_Client/csharp_test_client.csproj b/Tutorials/PvPGameServer_Client/csharp_test_client.csproj
index 7a62f55..88ff92e 100644
--- a/Tutorials/PvPGameServer_Client/csharp_test_client.csproj
+++ b/Tutorials/PvPGameServer_Client/csharp_test_client.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFramework>net8.0-windows10.0.17763.0</TargetFramework>
     <OutputType>WinExe</OutputType>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <UseWindowsForms>true</UseWindowsForms>
diff --git a/Tutorials/PvPGameServer_Client/mainForm.cs b/Tutorials/PvPGameServer_Client/mainForm.cs
index 7ecdd32..d67e252 100644
--- a/Tutorials/PvPGameServer_Client/mainForm.cs
+++ b/Tutorials/PvPGameServer_Client/mainForm.cs
@@ -5,12 +5,15 @@
 using System.Data;
 using System.Drawing;
 using System.Linq;
+using System.Runtime.Versioning;
 using System.Text;
 using System.Threading.Tasks;
+using System.Threading.Tasks.Dataflow;
 using System.Windows.Forms;
 
 namespace csharp_test_client
 {
+    [SupportedOSPlatform("windows10.0.177630")]
     public partial class mainForm : Form
     {
         ClientSimpleTcp Network = new ClientSimpleTcp();
@@ -94,6 +97,7 @@ private void btnDisconnect_Click(object sender, EventArgs e)
             Network.Close();
         }
 
+        // 에코
         private void button1_Click(object sender, EventArgs e)
         {
             if (string.IsNullOrEmpty(textSendText.Text))
@@ -103,8 +107,10 @@ private void button1_Click(object sender, EventArgs e)
             }
 
             var body = Encoding.UTF8.GetBytes(textSendText.Text);
-
-            PostSendPacket(PACKET_ID.PACKET_ID_ECHO, body);
+            var packetData = new byte[body.Length + MsgPackPacketHeadInfo.HeadSize];
+            Buffer.BlockCopy(body, 0, packetData, MsgPackPacketHeadInfo.HeadSize, body.Length);
+           
+            PostSendPacket(PACKET_ID.PACKET_ID_ECHO, packetData);
 
             DevLog.Write($"Echo 요청:  {textSendText.Text}, {body.Length}");
         }