我在练习这个的时候
private void button1_Click(object sender, EventArgs e)
        {
            TcpListener tcplistener = null;
            IPAddress ipaddress = IPAddress.Parse(textBox1.Text);
            int port =Convert.ToInt32(textBox2.Text);
            tcplistener = new TcpListener(ipaddress, port);
            tcplistener.Start();
            richTextBox1.Text = "等待连接...\n";
            TcpClient tcpclient = null;
            if (tcplistener.Pending())
            {
                tcpclient = tcplistener.AcceptTcpClient();

            }
            else
            {
                tcpclient =new TcpClient(textBox1.Text,port);
            }
            richTextBox1.Text +="连接成功!!";
            tcpclient.Close();
            tcplistener.Stop();

        }


运行结果 地址无效,我输入的地址是局域网的ip.
运行:telnet ip 1433 可行!!