Windows Forms: TCP/IP Client & Server in C#

SimpleTCP is simple and straightforward library for TCP client and servers. It's extremely useful for reading/writing with line-by-line command interfaces. Supports binary and string messages, automatic string trimming, and end-of-message delimiter (newline by default).

Open your Visual Studio, then click New Project, then select Visual C# on the left, then Windows and then select Windows Forms Application. Enter your project name and then click OK button.

Next, Right click on your project select Manage NuGet Packages -> Search simpletcp -> Install

Open your form designer, then design a client form that allows you to send messages to the server. You can layout your TCP Client form as shown below.

C# TCP Client Application

Do the same way for TCP Server form.

C# TCP Server Application

You should change the host and port to connect over the network, through the network you should open the firewall to allow connection to your port.

Double-click the client form, then add a Form_Load event handler that allows you to initialize SimpleTcpClient.

// c# tcp ip client example
SimpleTcpClient client;

private void Form1_Load(object sender, EventArgs e)
{
    client = new SimpleTcpClient();
    client.StringEncoder = Encoding.UTF8;
    client.DataReceived += Client_DataReceived;
}

If you want a TCP client that connects to 127.0.0.1 on port 8910

//  c# server client tcp
var client = new SimpleTcpClient().Connect("127.0.0.1", 8910);

Double-click on the Connet button, then add a Click event handler that allows you to connect to 127.0.0.1 via 8910 port.

private void btnConnect_Click(object sender, EventArgs e)
{
    btnConnect.Enabled = false;
    //Connect to server
    client.Connect(txtHost.Text, Convert.ToInt32(txtPort.Text));
}

You need to handle the DataReceived event allow you to add text to the textbox control.

// c# tcp windows ip
private void Client_DataReceived(object sender, SimpleTCP.Message e)
{
    //Update message to txtStatus
    txtStatus.Invoke((MethodInvoker)delegate ()
    {
        txtStatus.Text += e.MessageString;
    });
}

Double-click on the Send button, then add a Click event handler allows you to send data to server.

// c# send tcp message
private void btnSend_Click(object sender, EventArgs e)
{
    client.WriteLineAndGetReply(txtMessage.Text, TimeSpan.FromSeconds(3));
}

We will send the message from textbox control to the server and get the reply that it sends within 3 seconds.

Open your server form, then handle code allows you to receive message from client.

Here is a tcp c# server example.

Double-click on the server form, then add a Form_Load event handler. We will initialize SimpleTcpServer

// c# tcp server windows
SimpleTcpServer server;
private void Form1_Load(object sender, EventArgs e)
{
    server = new SimpleTcpServer();
    server.Delimiter = 0x13;//enter
    server.StringEncoder = Encoding.UTF8;
    server.DataReceived += Server_DataReceived;
}

StringEncoder use to change the text encoding that the client and server uses when sending and receiving strings.

If you want a TCP server that listens on port 8910 on all the IP addresses on the machine you can use snippet below.

//  tcp c# server tcpserver
var server = new SimpleTcpServer().Start(8910);

Double-click on the Start button, then add a Click event handler allows you to listens via IP and Port that you enter from textbox control

// tcp server c#
private void btnStart_Click(object sender, EventArgs e)
{
    //Start server host
    txtStatus.Text += "Server starting...";
    System.Net.IPAddress ip = System.Net.IPAddress.Parse(txtHost.Text);
    server.Start(ip, Convert.ToInt32(txtPort.Text));
}

Double-click on the Stop button, then add a Click event handler that allows you to stop listening.

// c# tcp server simple
private void btnStop_Click(object sender, EventArgs e)
{
    if (server.IsStarted)
        server.Stop();
}

You can also handle DataReceived event from server form allows you to reply message to client.

// c# tcp methodinvoker server
private void Server_DataReceived(object sender, SimpleTCP.Message e)
{
    //Update mesage to txtStatus
    txtStatus.Invoke((MethodInvoker)delegate ()
    {
        txtStatus.Text += e.MessageString;
        e.ReplyLine(string.Format("You said: {0}", e.MessageString));
    });
}

If you want to get the IP addresses that the server is listening on you can use the GetListeningIPs method.

var listeningIps = server.GetListeningIPs();

Or you want to get only the IPv4 addresses the server is listening on.

var listeningV4Ips = server.GetListeningIPs().Where(ip => ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork);

And if you want to know how many clients are connected to the server you can use the ConnectedClientsCount property.

int clientsConnected = server.ConnectedClientsCount;

So you have completed the tcp ip c# example using SimpleTCP library.

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