我正在尝试模拟与现有服务器通信的客户端程序。我使用过wireshark，可以看到来回的消息。客户端程序-连接并发送一个字符串

9 0 0 99 3 0 CR LF 
CLIENT SEND
0.001157    192.168.0.210   192.168.0.197   TCP 69  61517 → 22223 [PSH, ACK] Seq=1 Ack=1 Win=131328 Len=15

然后一个空字符串只是

CR LF
0.001232    192.168.0.210   192.168.0.197   TCP 56  61517 → 22223 [FIN, PSH, ACK] Seq=16 Ack=1 Win=131328 Len=2

服务器以确认字符和返回文本消息响应，然后是CRLF

SERVER RESPONSE
0.002383    192.168.0.197   192.168.0.210   TCP 60  22223 → 61517 [ACK] Seq=1 Ack=19 Win=525568 Len=0
0.004112    192.168.0.197   192.168.0.210   TCP 66  22223 → 61517 [PSH, ACK] Seq=1 Ack=19 Win=525568 Len=12
0.004113    192.168.0.197   192.168.0.210   TCP 60  22223 → 61517 [FIN, PSH, ACK] Seq=13 Ack=19 Win=525568 Len=2

当我尝试模拟客户端时-一切似乎都一样，除了我没有得到[FIN， PSH，确认字符]只是一个[PSH，确认字符]，服务器没有响应。在我的实验中，我发现如果我在写入服务器后关闭流，我可以在wireshark上看到响应是send（但是现在链接关闭了，所以我无法获得它）有人知道如何在保持连接存活的同时生成[FIN，PSH，确认字符]吗？？

我的发送消息例程

Public Async Sub SendMessage(ByVal msg As String) 'Handles sendButton.Click
    Try

        If client IsNot Nothing AndAlso client.Connected Then

            Dim stream As NetworkStream = client.GetStream
            Dim myBytes2() As Byte = Encoding.Default.GetBytes(msg)
            Try
                Await stream.WriteAsync(myBytes2, 0, myBytes2.Length)
                'stream.Close()
            Catch ioex As System.IO.IOException
                DisplayLog("Server terminated connection")
            Catch odex As ObjectDisposedException
                DisplayLog("client terminated connection")
            Catch er As Exception
                DisplayLog("ERROR Module:{" & GetModuleName(er) & "}" & Information.Err().Number & " Mess:" & er.Message)
            End Try
        End If
    Catch er As Exception
        DisplayLog("ERROR Module:{" & GetModuleName(er) & "}" & Information.Err().Number & " Mess:" & er.Message)
    End Try


End Sub