我正在尝试拦截数据包并能够阻止它们进入/传出特定域
为了做到这一点，我使我的（java）程序将域添加到hosts文件，重定向到我自己的公共ipv4地址（这无关紧要，它不能是真正的IP，我必须能够拦截它，重定向到我自己的IP，确保世界上没有其他人收到它）。其次，我让程序监听该信号并将其重新发送到真实服务器的不同源端口。 （已经处理了校验和更改）现在计划是接收响应并执行完全相同的操作，但现在通过编辑源ip（在本例中为我自己的公共IP）和目标端口
这应该创建一个程序，我在连接之间是一种中间人
但它没有按预期工作，当我得到服务器的响应（标志SYN / ACK）时，它会自动从我随机选择的端口发回一个RST标志（IPv4 / TCP），这是不一样的作为真实客户端的端口
我不知道是否有更好的方法可以做到这一点（可能有）以及如何防止我遇到的问题，我无法在互联网上找到类似的东西。任何形式的帮助/提示都将不胜感激
请记住，我现在正在使用jnetpscape，继续我正在做的事情会很高兴
编辑（代码）：
这是“HConnection”课程（没有完全展示但是所有重要的事情）：
public class HConnection {
private volatile int state = -1; // current state of the program
private volatile boolean HostFileEdited = false;
private volatile String domain = null;
private volatile boolean waitingConnection = false;
private volatile String ipOfDomain = null; // string of the server adress
private volatile byte[] ipofdomb; //4 bytes of the server adress
private volatile String myIpAdr = null; //my IP adress
private volatile byte[] myIpb; //my public IP in 4 bytes
private volatile byte[] port = null; //port of proxy
private volatile byte[] falseport = null; //port of client
private volatile ServerSocket server;
public HConnection() {
try {
server = new ServerSocket(0);
byte[] tempPortb = ByteBuffer.allocate(4).putInt(server.getLocalPort()).array();
System.out.println(server.getLocalPort());
port = new byte[]{tempPortb[2], tempPortb[3]};
(new Thread() {
public void run() {
try {
server.accept();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
}).start();
state = 0;
} catch (UnknownHostException e) {System.out.println("fail");} catch (IOException e) {System.out.println("fail");}
}
public String getPublicIP () {
try{
myIpAdr = new BufferedReader(new InputStreamReader(new URL("http://checkip.amazonaws.com/").openStream())).readLine();
System.out.println(myIpAdr);
InetAddress ip = InetAddress.getByName(myIpAdr);
myIpb = ip.getAddress();
return myIpAdr;
}
catch (Exception e){}
return null;
}
public void setUrl(String domain) {
this.domain = domain;
}
public int getState() {
return state;
}
public void prepare() {
try{
URL urlofsite = new URL("https://"+domain);
InetAddress address = InetAddress.getByName(urlofsite.getHost());
ipOfDomain = address.getHostAddress();
System.out.println(ipOfDomain);
ipofdomb = address.getAddress();
addToHostsFile(getPublicIP() + "\t" + domain);
state = 1;
}
catch(Exception e){}
}
public void abort() {
removeFromHostsFile(domain);
HostFileEdited = false;
state = -1;
try {
server.close();
} catch (IOException e) { }
waitingConnection = false;
}
public void awaitConnection() {
if (state == 1) {
waitingConnection = true;
System.out.println("stap1");
StringBuilder errbuf = new StringBuilder(); // For any error msgs
int snaplen = 64 * 1024; // Capture all packets, no truncation
int flags = Pcap.MODE_PROMISCUOUS; // capture all packets
int timeout = 0; // 10 seconds in millis
Pcap pcap = Pcap.openLive("wlp4s0", snaplen, flags, timeout, errbuf);
if (pcap == null) {
System.err.printf("Error while opening device for capture: "
+ errbuf.toString());
return;
}
PcapHeader hdr = new PcapHeader(JMemory.POINTER);
JBuffer buf = new JBuffer(JMemory.POINTER);
int id = JRegistry.mapDLTToId(pcap.datalink());
while (HostFileEdited && waitingConnection && state == 1 && pcap.nextEx(hdr, buf) == Pcap.NEXT_EX_OK) {
PcapPacket packet = new PcapPacket(hdr, buf);
try {
packet.scan(id);
TcpPacket pkt = new TcpPacket(packet);
if (pkt.isTcp()) {
if (pkt.destinationIPequals(myIpAdr) && pkt.getDestinationPort() == 443 && (falseport == null || Arrays.equals(pkt.getSourcePortb(), falseport))) {
if (falseport == null) {
falseport = pkt.getSourcePortb();
}
pkt.changeDestinationIP(ipofdomb);
pkt.changeSourcePort(port);
pkt.iPchecksumFix();
pkt.tcPchecksumFix();
ByteBuffer b = ByteBuffer.wrap(pkt.getPacketInBytes());
System.out.println("10");
System.out.println("OUT"+ (pcap.sendPacket(b)));
}
else if (pkt.sourceIPequals(ipOfDomain) && pkt.getSourcePort() == 443 && falseport != null && Arrays.equals(pkt.getDestinationPortb(),port) ) {
pkt.changeSourceIP(myIpb);
pkt.changeDestinationPort(falseport);
pkt.iPchecksumFix();
pkt.tcPchecksumFix();
ByteBuffer b = ByteBuffer.wrap(pkt.getPacketInBytes());
System.out.println("IN"+ pcap.sendPacket(b));
}
}
}
catch (Exception e) {}
}
System.out.println("stap2");
if (state == 1 && waitingConnection == true) state = 2;
waitingConnection = false;
}
}
}
“awaitConnection（）”方法目前正在发生大多数事情。但这只是我的计划的开始
从主类（SWT Designer）调用HConnection：
private Button btnNewButton_1;
private HConnection connectie;
private void btnConnect_clicked(SelectionEvent e) throws InterruptedException {
if (btnNewButton_1.getText().equals("Connect")) {
String Url = combo.getText();
connectie = new HConnection();
connectie.setUrl(Url);
connectie.prepare();
lblNewLabel_2.setText("Waiting -> client");
new Thread(new Runnable() {
public void run() {
connectie.awaitConnection();
Display.getDefault().asyncExec(new Runnable() {
public void run() {
if (connectie.getState() == 2) {
lblNewLabel_2.setText("Replacing URL");
}
else {
lblNewLabel_2.setText("Failed");
connectie.abort();
btnNewButton_1.setText("Connect");
}
}
});
if (connectie.getState() == 2) {
// go on with the rest of the program
}
}
}).start();
btnNewButton_1.setText("Abort");
}
else if(btnNewButton_1.getText().equals("Abort")) {
connectie.abort();
lblNewLabel_2.setText("Aborted");
btnNewButton_1.setText("Connect");
}
}
答案 0 :(得分：0)
以下代码接受连接，但不保留对生成的Socket实例的引用。此Socket符合垃圾回收条件，当发生这种情况时，它会自动关闭。然后，向该套接字发送数据的客户端将收到RST。
public void run() {
try {
server.accept();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}