‘客户端向这样写：在窗体说放两个文本框、两个标签、两个按钮、一个列表框
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Imports System.Net
Imports System.Net.Sockets
Imports System.IO
Imports System.Threading
Public Class Form1
'网络基础数据流
Private ns As NetworkStream
Private swriter As StreamWriter
Private nsread As StreamReader
Private tcpclient As TcpClient
Private tcpconnected As Boolean = False
Private clisocket As Socket
Private mythread As Thread
'发送
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If Me.TextBox2.Text "" Then
swriter.WriteLine(Me.TextBox2.Text)
swriter.Flush()
Me.TextBox2.Text = ""
Else
MessageBox.Show("发送信息不能为空！", "错误提示")
End If
End Sub
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
'建立连连接
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim ipremote As IPAddress
Dim tcpclient As TcpClient
Try
ipremote = IPAddress.Parse(Me.TextBox1.Text)
Catch ex As Exception
MessageBox.Show("IP地址不合法！", "错误提示")
End Try
Try
tcpclient = New TcpClient(Me.TextBox1.Text, 8000)
ns = tcpclient.GetStream
swriter = New StreamWriter(ns)
Me.StatusBar1.Text = "已经连接上"
Me.Button2.Enabled = False
Me.Button1.Enabled = True
tcpconnected = True
Catch ex As Exception
MessageBox.Show("无法与远程8000端口建立连接！", "错误提示")
End Try
End Sub
Private Sub listen()
Try
Dim tcplistener As New TcpListener(IPAddress.Parse("127.0.0.1"), 8000)
tcplistener.Start()
tcpclient = tcplistener.AcceptTcpClient
ns = tcpclient.GetStream()
nsread = New StreamReader(ns)
While True
Dim msg As String = nsread.ReadLine
If msg = "stop" Then
tcplistener.Stop()
ns.Close()
nsread.Close()
mythread.Abort()
Else
Dim mytime As String = DateTime.Now.ToShortTimeString
Me.ListBox1.Items.Add(mytime + " " + msg)
End If
End While
Catch ex As System.Security.SecurityException
MessageBox.Show("侦听失败！", "错误")
End Try
End Sub
End Class
Dim th As Threading.Thread
2 Dim tcpl As System.Net.Sockets.TcpListener
3
4 Private Sub Form1_Load()Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
5 th = New System.Threading.Thread(New System.Threading.ThreadStart(AddressOf MyListen))
6 th.Start()
7 End Sub
8
9 Public Sub SendMessage()Sub SendMessage(ByVal IP As String, ByVal SendMsg As String)
10 Try
11 If IP "" Then
12 Dim tcpc As New System.Net.Sockets.TcpClient(IP, 5656)
13 Dim tcpStream As Net.Sockets.NetworkStream = tcpc.GetStream
14 Dim reqStream As New IO.StreamWriter(tcpStream)
15 reqStream.Write(SendMsg)
16 reqStream.Flush()
17 tcpStream.Close()
18 tcpc.Close()
19 End If
20 Catch ex As Exception
21 MsgBox(ex.Message.ToString)
22 End Try
23 End Sub
24 Private Sub MyListen()Sub MyListen()
25 Try
26 Dim ipAddress As System.Net.IPAddress = System.Net.Dns.Resolve(System.Net.Dns.GetHostName).AddressList(0)
27 tcpl = New System.Net.Sockets.TcpListener(ipAddress, 5656)
28 tcpl.Start()
29 While True
30 Dim s As System.Net.Sockets.Socket = tcpl.AcceptSocket()
31 Dim MyBuffer(1024) As Byte
32 Dim i As Integer
33 i = s.Receive(MyBuffer)
34 If i 0 Then
35 Dim lstrRec As String
36 Dim j As Integer
37 For j = 0 To i - 1
38 TextBox1.Text += Chr(MyBuffer(j)) ","
39 Next
40 End If
41 End While
42 Catch ex As Exception
43 MsgBox(ex.Message.ToString)
44 End Try
45 End Sub
46
47 Private Sub Button1_Click()Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
48 SendMessage("192.168.0.61", TextBox2.Text)
49 End Sub
需要出口设备进行映射内部地址；或使用打洞技术穿透NAT,但使用TCP打洞非常困难。
参考
穿透NAT是非常困难的，因为NAT的过程中在出口路由器上的Port已经不是你定义的iPort了，具体是多少也不固定