【发布时间】：2014-09-18 17:55:03
【问题描述】：
我正在创建一个模拟 VPN（实际上并没有创建到服务器的真实连接）来获取所有传入和传出的网络字节（信息）。
现在我可以获取数据包并解析它们。例如，我得到了什么：
IP 版本：4 标题长度：20 总长度：60 协议：6 源IP：10.0.2.0 目标IP：5.20.5.59 主机名：clients4.google.com
我想知道我应该怎么做以及如何连接到网站/应用程序（目前无法连接）。
在这个网站上：http://www.thegeekstuff.com/2014/06/android-vpn-service/ 写道，需要进行这些步骤：
- 从 TUN 获取 IP 数据包。与所有 VPN 服务一样。
- 提取第 4 层信息。协议类型（例如 TCP/UDP）及其 有效载荷是必须的。由于 TCP 中有一个握手过程，之前 从中获取实际有效负载数据，我们需要写回 先握手包。
- 选择对应的socket发送payload。由于这一步是 在第 4 层工作，所以我们需要保存套接字并尝试获取 稍后返回数据。如果有返回数据，我们需要通过 这些数据包到 TUN。
- 从套接字获取数据包，并构建第 3 层数据包。首先，我们需要 构建一个有效的第 4 层数据包。 UDP 比 4 字节更容易一些 UDP头只包含源地址、源端口、目的 地址，目的港。 TCP 更复杂，因为它是一个状态
- 连接，序列号和确认号应该是 正确设置。然后，使用第 4 层数据包作为有效载荷，我们需要 构建一个有效的第 3 层数据包。将 IP 数据包写回 TUN。与...一样 所有 VPN 服务都可以。
在第 2 步，我从数据包中获取信息。但不要不明白它应该如何进一步完成。也许有人可以详细解释我。另外，当我有 IP 地址时，也许可以告诉我如何获取目的地端口。还有代码：
public class VPN extends VpnService implements Handler.Callback, Runnable {
private static final String TAG = "VpnService";
private String mServerAddress = "127.0.0.1";
private int mServerPort = 55555;
private Handler mHandler;
private Thread mThread;
private ParcelFileDescriptor mInterface;
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
if (mHandler == null) {
mHandler = new Handler(this);
}
if (mThread != null) {
mThread.interrupt();
}
mThread = new Thread(this, "VpnThread");
mThread.start();
return START_STICKY;
}
@Override
public void onDestroy() {
if (mThread != null) {
mThread.interrupt();
}
super.onDestroy();
}
@Override
public boolean handleMessage(Message message) {
if (message != null) {
Toast.makeText(this, (String) message.obj, Toast.LENGTH_SHORT).show();
}
return true;
}
@Override
public synchronized void run() {
try {
Log.i(TAG, "Starting");
InetSocketAddress server = new InetSocketAddress(mServerAddress, mServerPort);
run(server);
} catch (Exception e) {
Log.e(TAG, "Got " + e.toString());
try {
mInterface.close();
} catch (Exception e2) { }
Message msgObj = mHandler.obtainMessage();
msgObj.obj = "Disconnected";
mHandler.sendMessage(msgObj);
} finally {
}
}
DatagramChannel mTunnel = null;
protected boolean run(InetSocketAddress server) throws Exception {
boolean connected = false;
mTunnel = DatagramChannel.open();
if (!protect(mTunnel.socket())) {
throw new IllegalStateException("Cannot protect the tunnel");
}
mTunnel.connect(server);
mTunnel.configureBlocking(false);
handshake();
connected = true;
Message msgObj = mHandler.obtainMessage();
msgObj.obj = "Connected";
mHandler.sendMessage(msgObj);
new Thread ()
{
public void run ()
{
FileInputStream in = new FileInputStream(mInterface.getFileDescriptor());
ByteBuffer packet = ByteBuffer.allocate(32767);
DatagramChannel tunnel = mTunnel;
FileOutputStream out = new FileOutputStream(mInterface.getFileDescriptor());
int length;
String destIP;
try
{
while (true)
{
while ((length = in.read(packet.array())) > 0) {
packet.limit(length);
Log.d(TAG, "Total Length:" + mTunnel.socket().getInetAddress());
mTunnel.write(packet);
packet.flip();
TCP_IP TCP_debug = new TCP_IP(packet);
TCP_debug.debug();
destIP = TCP_debug.getDestination();
// InetAddress address = InetAddress.getByName(destIP);
// System.out.println(address.getHostAddress()); // Gaunamas IP (185.11.24.36)
// System.out.println(address.getHostName()); // www.15min.lt
out.write(packet.array(), 0, length);
packet.clear();
Thread.sleep(100);
}
}
}
catch (IOException e)
{
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
}.start();
return connected;
}
private void makeConnection(String destination, int port) {
try {
run(new InetSocketAddress(destination, port));
}
catch (Exception e) {
Log.d(TAG, "klaida jungiantis");
}
}
private void handshake() throws Exception {
if (mInterface == null)
{
Builder builder = new Builder();
//builder.setMtu(1500);
//builder.addAddress("10.0.2.0", 32);
// builder.addRoute("0.0.0.0", 0);
builder.addAddress("192.168.0.1", 24);
builder.addDnsServer("8.8.8.8");
builder.addRoute("0.0.0.0", 0);
try {
mInterface.close();
} catch (Exception e) {
// ignore
}
mInterface = builder.setSession("VPN'as").establish();
}
}
}
public class TCP_IP extends VPN {
private ByteBuffer packet;
private String hostname;
private String destIP;
private String sourceIP;
private int version;
private int protocol;
private int port;
public TCP_IP(ByteBuffer pack) {
this.packet = pack;
}
public void debug() {
int buffer = packet.get();
int headerlength;
int temp;
version = buffer >> 4;
headerlength = buffer & 0x0F;
headerlength *= 4;
System.out.println("IP Version:"+version);
System.out.println("Header Length:"+headerlength);
String status = "";
status += "Header Length:"+headerlength;
buffer = packet.get(); //DSCP + EN
buffer = packet.getChar(); //Total Length
System.out.println( "Total Length:"+buffer);
buffer = packet.getChar(); //Identification
buffer = packet.getChar(); //Flags + Fragment Offset
buffer = packet.get(); //Time to Live
buffer = packet.get(); //Protocol
protocol = buffer;
System.out.println( "Protocol:"+buffer);
status += " Protocol:"+buffer;
buffer = packet.getChar(); //Header checksum
byte buff = (byte)buffer;
sourceIP = "";
buff = packet.get(); //Source IP 1st Octet
temp = ((int) buff) & 0xFF;
sourceIP += temp;
sourceIP += ".";
buff = packet.get(); //Source IP 2nd Octet
temp = ((int) buff) & 0xFF;
sourceIP += temp;
sourceIP += ".";
buff = packet.get(); //Source IP 3rd Octet
temp = ((int) buff) & 0xFF;
sourceIP += temp;
sourceIP += ".";
buff = packet.get(); //Source IP 4th Octet
temp = ((int) buff) & 0xFF;
sourceIP += temp;
System.out.println( "Source IP:"+sourceIP);
status += " Source IP:"+sourceIP;
destIP = "";
buff = packet.get(); //Destination IP 1st Octet
temp = ((int) buff) & 0xFF;
destIP += temp;
destIP += ".";
buff = packet.get(); //Destination IP 2nd Octet
temp = ((int) buff) & 0xFF;
destIP += temp;
destIP += ".";
buff = packet.get(); //Destination IP 3rd Octet
temp = ((int) buff) & 0xFF;
destIP += temp;
destIP += ".";
buff = packet.get(); //Destination IP 4th Octet
temp = ((int) buff) & 0xFF;
destIP += temp;
System.out.println( "Destination IP:" + destIP);
status += " Destination IP:"+destIP;
}
public String getDestination() {
return destIP;
}
public int getProtocol() {
return protocol;
}
public int getPort() {
return port;
}
public String getHostname() {
return hostname;
}
public int getIPversion() { return version; }
}
【问题讨论】：
-
您找到解决方案了吗？我想做类似的事情。
-
您找到解决方案了吗？我想做类似的事情。
-
@CikLinas TCP_IP 来自哪里？那是图书馆吗？
标签： java android parsing ip vpn