Java Netty 框架自建 DNS 代理服务器教程
作者：小小怪下士
- 2023-01-09 湖南
本文字数：8900 字
阅读完需：约 29 分钟
前言
DNS 协议作为着互联网客户端-服务器通信模式得第一关，在当下每天都有成千上亿上网记录产生得当今社会，其重要性自然不可言喻。在国内比较有名得 DNS 服务器有电信得 114.114.114.114、阿里云得 223.5.5.5，DNSPod 得 119.29.29.29，配置一个好的 DNS 服务器可以缩短请求响应时间、降低 DNS 劫持概率，提升上网体验。
上面这些都是互联网公用 DNS 服务器，本文博主教大家使用 Java Netty 自建 DNS 代理服务器，目前网上对于使用 Netty 自建 DNS 服务器得教程良莠不齐，大多没有代理步骤，达不到博主想要得代理效果，因而创建此文。
一、自建 DNS 代理服务器有哪些优势
域名控制：对于特定域名可以自由控制访问权限（屏蔽对特定网站访问）
域名记录：记录局域网内各个主机得域名访问（记录员工上网记录）
配置内网域名：通过自建 DNS 服务器可以配置内网域名，节约成本
DNS 负载均衡：通过自建 DNS 服务器可以轻松实现对于访问域名得负载均衡配置
...
二、自建 DNS 代理服务器代码
添加域名黑名单文件，
resources文件夹下添加black_list.txt文件
google.com.facebook.com.
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初始化 BLACK_LIST_DOMAIN
private static final List<String> BLACK_LIST_DOMAIN = new ArrayList<>(); static { String s; try (InputStream is = DnsServer.class.getClassLoader().getResourceAsStream("black_list.txt"); BufferedReader br = new BufferedReader(new InputStreamReader(is))) { while (StrUtil.isNotBlank(s = br.readLine())) { BLACK_LIST_DOMAIN.add(s); } } catch (Exception e) { log.error(e.getMessage(), e); } }
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使用
UDP协议绑定本机 53 端口，并初始化ProxyUdpDNS 请求代理对象
@Slf4jpublic final class DnsServer { private static final List<String> BLACK_LIST_DOMAIN = new ArrayList<>(); static { ... }
public static void main(String[] args) throws Exception { ProxyUdp proxyUdp = new ProxyUdp(); proxyUdp.init(); final int[] num = {0}; final NioEventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group).channel(NioDatagramChannel.class) .handler(new ChannelInitializer<NioDatagramChannel>() { @Override protected void initChannel(NioDatagramChannel nioDatagramChannel) { nioDatagramChannel.pipeline().addLast(...); } }).option(ChannelOption.SO_BROADCAST, true);
int port = 53; ChannelFuture future = bootstrap.bind(port).addListener(future1 -> { log.info("server listening port:{}", port); });
future.channel().closeFuture().addListener(future1 -> { if (future.isSuccess()) { log.info(future.channel().toString()); } }); }}
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给
nioDatagramChannel.pipeline()添加ChannelHandler
nioDatagramChannel.pipeline().addLast(new DatagramDnsQueryDecoder()); nioDatagramChannel.pipeline().addLast(new SimpleChannelInboundHandler<DatagramDnsQuery>() { @Override protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsQuery msg) { try { DefaultDnsQuestion dnsQuestion = msg.recordAt(DnsSection.QUESTION); String name = dnsQuestion.name(); log.info(name + ++num[0]); Channel channel = ctx.channel(); int id = msg.id(); channel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(id))).set(msg); if (BLACK_LIST_DOMAIN.contains(name)) { DnsQuestion question = msg.recordAt(DnsSection.QUESTION); DatagramDnsResponse dnsResponse = getDatagramDnsResponse(msg, id, question); channel.writeAndFlush(dnsResponse); return; } proxyUdp.send(name, msg.id(), channel); } catch (Exception e) { log.error(e.getMessage(), e); } }
private DatagramDnsResponse getDatagramDnsResponse(DatagramDnsQuery msg, int id, DnsQuestion question) { DatagramDnsResponse dnsResponse = new DatagramDnsResponse(msg.recipient(), msg.sender(), id); dnsResponse.addRecord(DnsSection.QUESTION, question); DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord( question.name(), DnsRecordType.A, 600, Unpooled.wrappedBuffer(new byte[]{(byte) 192, (byte) 168, 1, 1})); dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer); return dnsResponse; }
@Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) { log.error(e.getMessage(), e); } }); nioDatagramChannel.pipeline().addLast(new DatagramDnsResponseEncoder());
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在 new SimpleChannelInboundHandler<DatagramDnsQuery>() 中 解析客户端 DNS 查询报文, 获取访问域名信息，如果访问域名在黑名单中，则通过 getDatagramDnsResponse() 直接返回 192.168.1.1 的 DNS 响应报文，反之则通过 proxyUdp 对象转发 DNS 查询。
ProxyUdp作为 DNS 查询代理类会通过send(String domain, int id, Channel serverChannel)方法传入 DnsServer 类收到的访问域名、DNS 事务 ID、serverChannel。随后包装访问域名请求 DNS 服务器114.114.114.114，最后通过new SimpleChannelInboundHandler<DatagramDnsResponse>()将收到的 DNS 响应报文通过上一步传入得serverChannel输出到客户端。
@Slf4jclass ProxyUdp { private Channel serverChannel; private Channel proxyChannel;
public void init() throws InterruptedException { EventLoopGroup proxyGroup = new NioEventLoopGroup(); Bootstrap b = new Bootstrap(); b.group(proxyGroup) .channel(NioDatagramChannel.class) .handler(new ChannelInitializer<DatagramChannel>() { @Override protected void initChannel(DatagramChannel ch) { ChannelPipeline p = ch.pipeline(); p.addLast(new DatagramDnsQueryEncoder()) .addLast(new DatagramDnsResponseDecoder()) .addLast(new SimpleChannelInboundHandler<DatagramDnsResponse>() { @Override public void channelActive(ChannelHandlerContext ctx) { log.info(ctx.channel().toString()); }
@Override protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsResponse msg) { DatagramDnsQuery dnsQuery = localChannel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(msg.id()))).get(); DnsQuestion question = msg.recordAt(DnsSection.QUESTION); DatagramDnsResponse dnsResponse = new DatagramDnsResponse(dnsQuery.recipient(), dnsQuery.sender(), msg.id()); dnsResponse.addRecord(DnsSection.QUESTION, question);
for (int i = 0, count = msg.count(DnsSection.ANSWER); i < count; i++) { DnsRecord record = msg.recordAt(DnsSection.ANSWER, i); if (record.type() == DnsRecordType.A) { // just print the IP after query DnsRawRecord raw = (DnsRawRecord) record; DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord( question.name(), DnsRecordType.A, 600, Unpooled.wrappedBuffer(ByteBufUtil.getBytes(raw.content()))); dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer); } }
serverChannel.writeAndFlush(dnsResponse); }
@Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) { log.error(e.getMessage(), e); } });
} }); proxyChannel = b.bind(0).sync().addListener(future1 -> { log.info("绑定成功"); }).channel(); }
public void send(String domain, int id, Channel serverChannel) { this.serverChannel = serverChannel; DnsQuery query = new DatagramDnsQuery(null, new InetSocketAddress("114.114.114.114", 53), id).setRecord( DnsSection.QUESTION, new DefaultDnsQuestion(domain, DnsRecordType.A)); this.proxyChannel.writeAndFlush(query); }}
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自建 DNS 服务器全部代码
@Slf4jpublic final class DnsServer { private static final List<String> BLACK_LIST_DOMAIN = new ArrayList<>(); static { String s; try (InputStream is = DnsServer.class.getClassLoader().getResourceAsStream("black_list.txt"); BufferedReader br = new BufferedReader(new InputStreamReader(is))) { while (StrUtil.isNotBlank(s = br.readLine())) { BLACK_LIST_DOMAIN.add(s); } } catch (Exception e) { log.error(e.getMessage(), e); } }
public static void main(String[] args) throws Exception { ProxyUdp proxyUdp = new ProxyUdp(); proxyUdp.init(); final int[] num = {0}; final NioEventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group).channel(NioDatagramChannel.class) .handler(new ChannelInitializer<NioDatagramChannel>() { @Override protected void initChannel(NioDatagramChannel nioDatagramChannel) { nioDatagramChannel.pipeline().addLast(new DatagramDnsQueryDecoder()); nioDatagramChannel.pipeline().addLast(new SimpleChannelInboundHandler<DatagramDnsQuery>() {
@Override protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsQuery msg) { try { DefaultDnsQuestion dnsQuestion = msg.recordAt(DnsSection.QUESTION); String name = dnsQuestion.name(); log.info(name + ++num[0]); Channel channel = ctx.channel(); int id = msg.id(); channel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(id))).set(msg); if (BLACK_LIST_DOMAIN.contains(name)) { DnsQuestion question = msg.recordAt(DnsSection.QUESTION); DatagramDnsResponse dnsResponse = getDatagramDnsResponse(msg, id, question); channel.writeAndFlush(dnsResponse); return; } proxyUdp.send(name, msg.id(), channel); } catch (Exception e) { log.error(e.getMessage(), e); } }
private DatagramDnsResponse getDatagramDnsResponse(DatagramDnsQuery msg, int id, DnsQuestion question) { DatagramDnsResponse dnsResponse = new DatagramDnsResponse(msg.recipient(), msg.sender(), id); dnsResponse.addRecord(DnsSection.QUESTION, question);
// just print the IP after query DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord( question.name(), DnsRecordType.A, 600, Unpooled.wrappedBuffer(new byte[]{(byte) 192, (byte) 168, 1, 1})); dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer); return dnsResponse; }
@Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) { log.error(e.getMessage(), e); } }); nioDatagramChannel.pipeline().addLast(new DatagramDnsResponseEncoder());
} }).option(ChannelOption.SO_BROADCAST, true);
int port = 553; ChannelFuture future = bootstrap.bind(port).addListener(future1 -> { log.info("server listening port:{}", port); });
future.channel().closeFuture().addListener(future1 -> { if (future.isSuccess()) { log.info(future.channel().toString()); } }); }}
@Slf4jclass ProxyUdp { private Channel localChannel; private Channel proxyChannel;
public void init() throws InterruptedException { EventLoopGroup proxyGroup = new NioEventLoopGroup(); Bootstrap b = new Bootstrap(); b.group(proxyGroup) .channel(NioDatagramChannel.class) .handler(new ChannelInitializer<DatagramChannel>() { @Override protected void initChannel(DatagramChannel ch) { ChannelPipeline p = ch.pipeline(); p.addLast(new DatagramDnsQueryEncoder()) .addLast(new DatagramDnsResponseDecoder()) .addLast(new SimpleChannelInboundHandler<DatagramDnsResponse>() { @Override public void channelActive(ChannelHandlerContext ctx) { log.info(ctx.channel().toString()); }
@Override protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsResponse msg) { DatagramDnsQuery dnsQuery = localChannel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(msg.id()))).get(); DnsQuestion question = msg.recordAt(DnsSection.QUESTION); DatagramDnsResponse dnsResponse = new DatagramDnsResponse(dnsQuery.recipient(), dnsQuery.sender(), msg.id()); dnsResponse.addRecord(DnsSection.QUESTION, question);
for (int i = 0, count = msg.count(DnsSection.ANSWER); i < count; i++) { DnsRecord record = msg.recordAt(DnsSection.ANSWER, i); if (record.type() == DnsRecordType.A) { // just print the IP after query DnsRawRecord raw = (DnsRawRecord) record; DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord( question.name(), DnsRecordType.A, 600, Unpooled.wrappedBuffer(ByteBufUtil.getBytes(raw.content()))); dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer); } }
localChannel.writeAndFlush(dnsResponse); }
@Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) { log.error(e.getMessage(), e); } });
} }); proxyChannel = b.bind(0).sync().addListener(future1 -> { log.info("绑定成功"); }).channel(); }
public void send(String domain, int id, Channel localChannel) { this.localChannel = localChannel; DnsQuery query = new DatagramDnsQuery(null, new InetSocketAddress("114.114.114.114", 53), id).setRecord( DnsSection.QUESTION, new DefaultDnsQuestion(domain, DnsRecordType.A)); this.proxyChannel.writeAndFlush(query); }}
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三、本地测试
修改本机 DNS 设置(win11)，修改首选、备选 DNS 地址为 127.0.0.1
打开命令行工具，执行 DNS 缓存清除命令
ipconfig/flushdns
自此就可以打开浏览器访问常用网站，看是否能正常访问，来验证自建的 DNS 服务器效果了
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