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Android DNS拦截端口绑定问题解决方案
从日志可以看出，您遇到了两个关键问题：
问题分析
- 绑定53端口失败：
Permission denied 错误 - iptables重定向失败：缺少root权限
解决方案
方案1：使用非特权端口 + iptables重定向（需要root权限）
private static final int PORT_DNS = 53;
private static final int PORT_FALLBACK = 5353;
private void startDnsHijackServer() {
try {
dnsSocket = new DatagramSocket(PORT_DNS);
WifiLog.i(TAG, "DNS劫持服务器启动在端口 " + PORT_DNS);
startDnsListening();
} catch (Exception e) {
WifiLog.e(TAG, "DNS服务器启动失败: " + e.getMessage());
startFallbackDnsServer();
}
}
private void startFallbackDnsServer() {
try {
dnsSocket = new DatagramSocket(PORT_FALLBACK);
WifiLog.i(TAG, "备选DNS服务器启动在端口 " + PORT_FALLBACK);
// 尝试设置iptables重定向
if (setupIptablesRedirect()) {
WifiLog.i(TAG, "iptables重定向设置成功");
} else {
WifiLog.w(TAG, "iptables重定向设置失败，将使用本地DNS服务");
}
startDnsListening();
} catch (Exception e) {
WifiLog.e(TAG, "备选DNS服务器启动失败: " + e.getMessage());
}
}
private boolean setupIptablesRedirect() {
try {
// 方法1：使用su命令（需要root）
String[] commands = {
"iptables -t nat -A OUTPUT -p udp --dport 53 -j REDIRECT --to-port " + PORT_FALLBACK,
"iptables -t nat -A OUTPUT -p tcp --dport 53 -j REDIRECT --to-port " + PORT_FALLBACK
};
Process process = Runtime.getRuntime().exec("su");
DataOutputStream os = new DataOutputStream(process.getOutputStream());
for (String command : commands) {
os.writeBytes(command + "\n");
}
os.writeBytes("exit\n");
os.flush();
return process.waitFor() == 0;
} catch (Exception e) {
WifiLog.e(TAG, "iptables重定向失败: " + e.getMessage());
return false;
}
}
private void startDnsListening() {
byte[] buffer = new byte[512];
while (isRunning && !dnsSocket.isClosed()) {
try {
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
dnsSocket.receive(packet);
new Thread(new DnsHandler(packet)).start();
} catch (Exception e) {
if (isRunning) {
WifiLog.e(TAG, "DNS接收错误: " + e.getMessage());
}
}
}
}
方案2：VPN方式（无需root权限，推荐）
public class DnsVpnService extends VpnService {
private static final String TAG = "DnsVpnService";
private ParcelFileDescriptor vpnInterface;
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Builder builder = new Builder();
builder.setMtu(1500);
builder.addAddress("10.8.0.2", 32);
builder.addRoute("0.0.0.0", 0);
builder.setSession("DNSInterceptor");
try {
vpnInterface = builder.establish();
// 启动DNS处理线程
new Thread(new DnsInterceptor()).start();
} catch (Exception e) {
WifiLog.e(TAG, "VPN建立失败: " + e.getMessage());
}
return START_STICKY;
}
private class DnsInterceptor implements Runnable {
@Override
public void run() {
try {
FileInputStream in = new FileInputStream(vpnInterface.getFileDescriptor());
while (true) {
// 在这里拦截和处理DNS请求
// 可以使用本地DNS服务器或者自定义DNS解析逻辑
}
} catch (Exception e) {
WifiLog.e(TAG, "DNS拦截器错误: " + e.getMessage());
}
}
}
@Override
public void onDestroy() {
if (vpnInterface != null) {
try {
vpnInterface.close();
} catch (Exception e) {
WifiLog.e(TAG, "关闭VPN接口错误: " + e.getMessage());
}
}
super.onDestroy();
}
}
方案3：使用本地DNS解析器
public class LocalDnsResolver {
private static final String TAG = "LocalDnsResolver";
private static final int DNS_PORT = 5353;
private DatagramSocket dnsSocket;
public void start() {
try {
dnsSocket = new DatagramSocket(DNS_PORT);
WifiLog.i(TAG, "本地DNS解析器启动在端口 " + DNS_PORT);
ExecutorService executor = Executors.newFixedThreadPool(10);
byte[] buffer = new byte[512];
while (!dnsSocket.isClosed()) {
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
dnsSocket.receive(packet);
executor.execute(new DnsQueryHandler(packet));
}
} catch (Exception e) {
WifiLog.e(TAG, "本地DNS解析器错误: " + e.getMessage());
}
}
private class DnsQueryHandler implements Runnable {
private final DatagramPacket originalPacket;
public DnsQueryHandler(DatagramPacket packet) {
this.originalPacket = packet;
}
@Override
public void run() {
try {
// 解析DNS查询
DNSMessage query = new DNSMessage(originalPacket.getData());
// 自定义DNS解析逻辑
DNSMessage response = resolveDnsQuery(query);
// 发送响应
byte[] responseData = response.toArray();
DatagramPacket responsePacket = new DatagramPacket(
responseData, responseData.length,
originalPacket.getAddress(), originalPacket.getPort()
);
dnsSocket.send(responsePacket);
} catch (Exception e) {
WifiLog.e(TAG, "DNS查询处理错误: " + e.getMessage());
}
}
private DNSMessage resolveDnsQuery(DNSMessage query) {
// 实现自定义DNS解析逻辑
// 可以返回指定的IP地址
return createCustomDnsResponse(query);
}
}
}
权限配置
在 AndroidManifest.xml 中添加：
<!-- VPN方式需要的权限 -->
<uses-permission android:name="android.permission.BIND_VPN_SERVICE" />
<service
android:name=".DnsVpnService"
android:permission="android.permission.BIND_VPN_SERVICE">
<intent-filter>
<action android:name="android.net.VpnService" />
</intent-filter>
</service>
<!-- 网络权限 -->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
建议
- 推荐使用VPN方案，因为它不需要root权限，兼容性更好
- 如果必须使用53端口，考虑将应用做成系统应用
- 在非root设备上，使用非特权端口配合DNS重定向配置
希望这些方案能帮助您解决问题！
