{"id":811,"date":"2018-10-09T11:45:20","date_gmt":"2018-10-09T02:45:20","guid":{"rendered":"https:\/\/vongg.com\/?p=811"},"modified":"2018-10-09T23:28:21","modified_gmt":"2018-10-09T14:28:21","slug":"%e9%80%9a%e8%bf%87iptables%e5%ae%9e%e7%8e%b0%e7%ab%af%e5%8f%a3%e8%bd%ac%e5%8f%91%e5%92%8c%e5%86%85%e7%bd%91%e5%85%b1%e4%ba%ab%e4%b8%8a%e7%bd%91-gooooood","status":"publish","type":"post","link":"https:\/\/vongg.com\/?p=811","title":{"rendered":"\u901a\u8fc7iptables\u5b9e\u73b0\u7aef\u53e3\u8f6c\u53d1\u548c\u5185\u7f51\u5171\u4eab\u4e0a\u7f51 gooooood"},"content":{"rendered":"<pre class=\"code\" data-lang=\"\" data-unlink=\"\"><\/pre>\n<p>http:\/\/xstarcd.github.io\/wiki\/Linux\/iptables_forward_internetshare.html<\/p>\n<ul>\n<li>\u539f\u6587\uff1a<a title=\"http:\/\/wwdhks.blog.51cto.com\/839773\/1154032\" href=\"http:\/\/wwdhks.blog.51cto.com\/839773\/1154032\" target=\"_blank\" rel=\"noopener\">http:\/\/wwdhks.blog.51cto.com\/839773\/1154032<\/a><\/li>\n<li>\u672c\u6587\u4f5c\u8005\uff1a\u5f20\u5929\u6210 zhangtiancheng#gmail.com \u8f6c\u53d1\u8bf7\u6ce8\u660e\u51fa\u5904\u3002<\/li>\n<\/ul>\n<p>iptables\u662f\u4e00\u4e2aLinux\u4e0b\u4f18\u79c0\u7684nat+\u9632\u706b\u5899\u5de5\u5177\uff0c\u6211\u4f7f\u7528\u8be5\u5de5\u5177\u4ee5\u8f83\u4f4e\u914d\u7f6e\u7684\u4f20\u7edfpc\u914d\u7f6e\u4e86\u4e00\u4e2a\u7075\u6d3b\u5f3a\u52b2\u7684\u9632\u706b\u5899+nat\u7cfb\u7edf,\u5c0f\u6709\u5fc3\u5f97\uff0c\u770b\u4e86\u7f51\u4e0a\u4e5f\u6709\u5f88\u591a\u8fd9\u65b9\u9762\u7684\u6587\u7ae0\uff0c\u4f46\u662f\u4f3c\u4e4e\u8981\u4e48\u8bf4\u7684\u6bd4\u8f83\u5c11\uff0c\u8981\u4e48\u5c31\u662f\u6bd4\u8f83\u504f\uff0c\u5185\u5bb9\u4e0d\u5168\uff0c\u5bb9\u6613\u8bef\u5bfc\uff0c\u6211\u7814\u7a76\u4e86\u4e00\u6bb5\u65f6\u95f4\u7684iptables\u540c\u65f6\u4e5f\u7528\u4e86\u5f88\u4e45\uff0c\u6709\u70b9\u6ef4\u7ecf\u9a8c\uff0c\u5199\u6765\u4f9b\u5927\u5bb6\u53c2\u8003\uff0c\u540c\u65f6\u4e5f\u5907\u65e5\u540e\u81ea\u5df1\u7ffb\u9605\u3002<\/p>\n<p>\u9996\u5148\u8981\u8bf4\u660e\u7684\u662f\uff0ciptables\u64cd\u4f5c\u7684\u662f2.4\u4ee5\u4e0a\u5185\u6838\u7684netfilter\u3002\u6240\u4ee5\u9700\u8981linux\u7684\u5185\u6838\u57282.4\u4ee5\u4e0a\u3002\u5176\u529f\u80fd\u4e0e\u5b89\u5168\u6027\u8fdc\u8fdc\u6bd4\u5176\u524d\u8f88ipfwadm,ipchains\u5f3a\u5927\uff0ciptables\u5927\u81f4\u662f\u5de5\u4f5c\u5728OSI\u4e03\u5c42\u7684\u4e8c\u3001\u4e09\u3001\u56db\u5c42\uff0c\u5176\u524d\u8f88ipchains\u4e0d\u80fd\u5355\u72ec\u5b9e\u73b0\u5bf9tcp\/udp port\u4ee5\u53ca\u5bf9mac\u5730\u5740\u7684\u7684\u5b9a\u4e49\u4e0e\u64cd\u4f5c\uff0c\u6240\u4ee5\u6211\u60f3ipchains\u5e94\u8be5\u662f\u4ec5\u4ec5\u5de5\u4f5c\u5728\u4e09\u5c42\u4e0a\u7684\u3002<\/p>\n<h2 id=\"toc_0.1\">netfilter\u5de5\u4f5c\u6d41\u7a0b<\/h2>\n<p>\u6211\u4eec\u5148\u7b80\u5355\u4ecb\u7ecd\u4e00\u4e0bnetfilter\u7684\u5927\u81f4\u5de5\u4f5c\u6d41\u7a0b\uff0c\u4e5f\u5c31\u662f\u4e00\u4e2a\u6570\u636e\u5305\uff08\u6216\u8005\u53eb\u5206\u7ec4\u3001packet,\u6211\u4e2a\u4eba\u4e60\u60ef\u53eb\u5305\uff09\u5728\u5230\u8fbelinux\u7684\u7f51\u7edc\u63a5\u53e3\u7684\u65f6\u5019 \uff08\u7f51\u5361\uff09\u5982\u4f55\u5904\u7406\u8fd9\u4e2a\u5305\uff0c\u7136\u540e\u518d\u4ecb\u7ecd\u4e00\u4e0b\u5982\u4f55\u7528iptables\u6539\u53d8\u6216\u8005\u8bf4\u63a7\u5236\u5bf9\u8fd9\u4e2a\u6570\u636e\u5305\u8fdb\u884c\u64cd\u4f5c\u3002<\/p>\n<ul>\n<li>netfilter\u5185\u90e8\u5206\u4e3a\u4e09\u4e2a\u8868\uff0c\u5206\u522b\u662f filter,nat,mangle\uff0c\u6bcf\u4e2a\u8868\u53c8\u6709\u4e0d\u540c\u7684\u64cd\u4f5c\u94fe\uff08Chains\uff09\u3002<\/li>\n<li>\u5728filter\uff08\u8fc7\u6ee4\uff09\u8868\u4e2d\uff0c\u4e5f\u5c31\u662f\u4ed6\u7684\u00a0<strong>\u9632\u706b\u5899\u529f\u80fd<\/strong>\u00a0\u7684\u8fd9\u4e2a\u8868\uff0c\u5b9a\u4e49\u4e86\u4e09\u4e2a Chain\u3002\u5206\u522b\u662fINPUT,FORWARD,OUTPUT\u3002\u4e5f\u5c31\u662f\u5bf9\u5305\u7684\u5165\u3001\u8f6c\u53d1\u3001\u51fa\u8fdb\u884c\u5b9a\u4e49\u7684\u4e09\u4e2a\u8fc7\u6ee4\u94fe\u3002\u5bf9\u4e8e\u8fd9\u4e2afilter\u8868\u7684\u64cd\u4f5c\u548c\u63a7\u5236\u4e5f\u662f\u6211\u4eec\u5b9e\u73b0\u9632\u706b\u5899\u529f\u80fd\u7684\u4e00\u4e2a\u91cd\u8981\u624b\u6bb5\uff1b<\/li>\n<li>\u5728nat(Network Address Translation\u3001\u7f51\u7edc\u5730\u5740\u7ffb\u8bd1)\u8868\u4e2d\uff0c\u4e5f\u5c31\u662f\u6211\u4eec\u7528\u4ee5\u5b9e\u73b0\u5730\u5740\u8f6c\u6362\u548c\u7aef\u53e3\u8f6c\u53d1\u529f\u80fd\u7684\u8fd9\u4e2a\u8868\uff0c\u5b9a\u4e49\u4e86PREROUTING, POSTROUTING,OUTPUT\u4e09\u4e2a\u94fe,\u4e0b\u9762\u6211\u4eec\u4f1a\u5bf9\u8fd9\u4e09\u4e2a\u94fe\u4f5c\u8be6\u7ec6\u7684\u8bf4\u660e\uff1b<\/li>\n<li>\u800cnetfilter\u7684mangle\u8868\u5219\u662f\u4e00\u4e2a\u81ea\u5b9a\u4e49\u8868\uff0c\u91cc\u9762\u5305\u62ec\u4e0a\u9762 \u7684filter\u4ee5\u53canat\u8868\u4e2d\u7684\u5404\u79cdchains\uff0c\u5b83\u53ef\u4ee5\u8ba9\u6211\u4eec\u8fdb\u884c\u4e00\u4e9b\u81ea\u5b9a\u4e49\u7684\u64cd\u4f5c\uff0c\u540c\u65f6\u8fd9\u4e2amangle\u8868\u4e2d\u7684chains\u5728netfilter\u5bf9\u5305 \u7684\u5904\u7406\u6d41\u7a0b\u4e2d\u5904\u5728\u4e00\u4e2a\u6bd4\u8f83\u4f18\u5148\u7684\u4f4d\u7f6e\u3002<\/li>\n<\/ul>\n<p>\u4e0b\u9762\u6709\u4e00\u5f20\u56fe\u6e05\u6670\u7684\u63cf\u7ed8\u4e86netfilter\u5bf9\u5305\u7684\u5904\u7406\u6d41\u7a0b\uff08\u8be5\u56fe\u6458\u81ea\u7f51\u4e0a\uff0c\u4e0d\u77e5\u4f5c\u8005\u662f\u8c01\uff0c\u5728\u6b64\u6df1\u8868\u656c\u610f\uff01\uff09\uff0c\u4e00\u822c\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u7528\u4e0d\u5230\u8fd9\u4e2amangle\u8868\uff0c\u5728\u8fd9\u91cc\u6211\u4eec\u5c31\u4e0d\u505a\u4ecb\u7ecd\u4e86\u3002<\/p>\n<pre class=\"code\" data-lang=\"\" data-unlink=\"\"><\/pre>\n<p>&nbsp;<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/xstarcd.github.io\/wiki\/img\/iptables_netfilter_chains.png\" alt=\"iptables\u00e5\u008c\u0085\u00e5\u00a4\u0084\u00e7\u0090\u0086\u00e6\u00b5\u0081\u00e7\u00a8\u008b\" \/><\/p>\n<p>&nbsp;<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/xstarcd.github.io\/wiki\/img\/iptables_entables.png\" alt=\"iptables_entables\u00e5\u00a4\u0084\u00e7\u0090\u0086\u00e6\u00b5\u0081\u00e7\u00a8\u008b\u00e5\u009b\u00be\" \/><\/p>\n<p>\u5927\u5bb6\u53ef\u4ee5\u770b\u5230\uff1a<\/p>\n<ul>\n<li>PREROUTING(DNAT)<\/li>\n<\/ul>\n<p>PREROUTING\u8fd9\u4e2achain\u5728\u6700\u524d\u9762\uff0c\u5f53\u4e00\u4e2a\u5305\u6765\u5230linux\u7684\u7f51\u7edc\u63a5\u53e3\u7684\u65f6\u5019\u5148\u8fc7mangle\u7684PREROUTING\uff1b\u7136\u540e\u662fnat\u7684PREROUTING,\u4ece\u8fd9\u4e2achain\u7684\u540d\u5b57\u6211\u4eec\u53ef\u4ee5\u770b\u51fa\uff0c\u8fd9\u4e2achain\u662f\u5728\u8def\u7531\u4e4b\u524d(pre-routing)\u8981\u8fc7\u7684\u3002<\/p>\n<p>\u4e3a\u4ec0\u4e48\u8981\u5728\u8def\u7531\u4e4b\u524d\u8fc7\u5462\uff1f\u5927\u5bb6\u53ef\u4ee5\u770b\u5230\u8fd9\u4e2a\u56fe\u4e0a\uff0c\u4e0a\u9762\u6709\u4e00\u4e2a\u83f1\u5f62\u7684\u90e8\u5206\u53ebROUTING,\u8fd9\u4e2aROUTING\u90e8\u5206\u5c31\u662fLinux\u7684route box,\u4e5f\u5c31\u662f\u8def\u7531\u7cfb\u7edf\uff0c\u5b83\u540c\u6837\u6709\u5f88\u9ad8\u6df1\u7684\u529f\u80fd\uff0c\u53ef\u4ee5\u5b9e\u73b0\u7b56\u7565\u8def\u7531\u7b49\u7b49\u4e00\u4e9b\u9ad8\u7ea7\u7279\u6027\uff0c\u6b64\u5904\u6211\u4eec\u4e0d\u505a\u8be6\u7ec6\u89e3\u91ca\u3002\u5355\u8bf4\u8fd9\u4e2aPREROUTING\u94fe\uff0c\u56e0\u4e3a\u5728\u8fd9\u4e2a\u94fe\u91cc\u9762\u6211\u4eec\u5bf9\u5305\u7684\u64cd\u4f5c\u662fDNAT,\u4e5f\u5c31\u662f\u6539\u53d8\u76ee\u7684\u5730\u5740\u548c\uff08\u6216\u7aef\u53e3\uff09\uff0c\u901a\u5e38\u7528\u5728\u7aef\u53e3\u8f6c\u53d1\uff0c\u6216\u8005nat\u5230\u5185\u7f51\u7684DMZ\u533a\uff0c\u4e5f\u5c31\u662f\u8bf4\u5f53\u4e00\u4e2a\u5305\u8fc7\u6765\u7684\u65f6\u5019\u6211\u4eec\u8981\u6539\u53d8\u5b83\u7684\u76ee\u7684\u5730\u5740\uff0c\u5927\u5bb6\u53ef\u4ee5\u60f3\u60f3,\u5982\u679c\u4e00\u4e2a\u5305\u5728\u6539\u53d8\u76ee\u7684\u5730\u5740\u4e4b\u524d\u5c31\u88ab\u6254\u8fdb\u4e86route box,\u8ba9\u7cfb\u7edf\u9009\u597d\u8def\u4e4b\u540e\u518d\u6539\u53d8\u76ee\u7684\u5730\u5740\uff0c\u90a3\u4e48\u9009\u8def\u5c31\u53ef\u80fd\u662f\u9519\u7684\uff0c\u6216\u8005\u8bf4\u6beb\u65e0\u610f\u4e49\u4e86\uff0c\u6240\u4ee5\uff0cPREROUTING\u8fd9\u4e2aChain\u4e00\u5b9a\u8981\u5728\u8fdbRouting \u4e4b\u524d\u505a\u3002<\/p>\n<p>\u6bd4\u5982\u8bf4\uff0c\u6211\u4eec\u7684\u516c\u7f51ip\u662f60.1.1.1\/24\uff0c\u4f4d\u4e8elinux\u4e2d\u7684eth0\u5185\u7f51ip\u662f10.1.1.1\/24\uff0c\u4f4d\u4e8elinux\u4e2d\u7684eth1, \u6211\u4eec\u7684\u5185\u7f51\u6709\u4e00\u53f0web\u670d\u52a1\u5668\uff0c\u5730\u5740\u662f10.1.1.2\/24,\u6211\u4eec\u600e\u4e48\u6837\u80fd\u8ba9internet\u7528\u6237\u901a\u8fc7\u8fd9\u4e2a\u516c\u7f51ip\u8bbf\u95ee\u6211\u4eec\u5185\u90e8\u7684\u8fd9\u4e2aweb\u670d\u52a1\u5668\u5462\uff1f \u6211\u4eec\u5c31\u53ef\u4ee5\u5728\u8fd9\u4e2aPREROUTING\u94fe\u4e0a\u9762\u5b9a\u4e49\u4e00\u4e2a\u89c4\u5219\uff0c\u628a\u8bbf\u95ee60.1.1.1:80\u7684\u7528\u6237\u7684\u76ee\u7684\u5730\u5740\u6539\u53d8\u4e00\u4e0b\uff0c\u6539\u53d8\u4e3a10.1.1.2:80,\u8fd9\u6837 \u5c31\u5b9e\u73b0\u4e86internet\u7528\u6237\u5bf9\u5185\u7f51\u670d\u52a1\u5668\u7684\u8bbf\u95ee\u4e86\uff0c\u5f53\u7136\u4e86\uff0c\u8fd9\u4e2a\u7aef\u53e3\u662f\u6bd4\u8f83\u7075\u6d3b\u7684\uff0c\u6211\u4eec\u53ef\u4ee5\u5b9a\u4e49\u4efb\u4f55\u4e00\u4e2a\u7aef\u53e3\u7684\u8f6c\u53d1\uff0c\u4e0d\u4e00\u5b9a\u662f80&#8211;&gt;80\uff0c\u5177\u4f53\u7684\u547d\u4ee4\u6211\u4eec\u5728\u4e0b\u9762\u7684\u4f8b\u5b50\u4e2d\u4ecb\u7ecd\uff0c\u8fd9\u91cc\u6211\u4eec\u53ea\u8c08\u6d41\u7a0b\u4e0e\u6982\u5ff5\u4e0a\u7684\u5b9e\u73b0\u65b9\u6cd5\u3002<\/p>\n<ul>\n<li>FORWARD<\/li>\n<\/ul>\n<p>\u597d\u4e86\uff0c\u6211\u4eec\u63a5\u7740\u5f80\u4e0b\u8d70\uff0c\u8fd9\u4e2a\u5305\u5df2\u7ecf\u8fc7\u4e86\u4e24\u4e2aPREROUTING\u94fe\u4e86\uff0c\u8fd9\u4e2a\u65f6\u5019\uff0c\u51fa\u73b0\u4e86\u4e00\u4e2a\u5206\u652f\u8f6c\u6298\u7684\u5730\u65b9\uff0c\u4e5f\u5c31\u662f\u56fe\u4e2d\u4e0b\u65b9\u7684\u90a3\u4e2a\u83f1\u5f62\uff08FORWARD\uff09,\u8f6c\u53d1\uff01\u8fd9\u91cc\u6709\u4e00\u4e2a\u5bf9\u76ee\u7684\u5730\u5740\u7684\u5224\u65ad\uff08\u8fd9\u91cc\u540c\u6837\u8bf4\u660e\u4e86PREROUTING\u4e00\u5b9a\u8981\u5728\u6700\u5148\uff0c\u4e0d\u4ec5\u8981\u5728route box\u4e4b\u524d\uff0c\u751a\u81f3\u662f\u8fd9\u4e2a\u5bf9\u76ee\u7684\u5730\u5740\u7684\u5224\u65ad\u4e4b\u524d\uff0c\u56e0\u4e3a\u6211\u4eec\u53ef\u80fd\u505a\u4e00\u4e2a\u53bb\u67d0\u67d0\u67d0ip\u7684\u5730\u65b9\u8f6c\u5230\u81ea\u5df1\u7684ip\u7684\u89c4\u5219\uff0c\u6240\u4ee5PREROUTING\u662f\u6700\u5148\u5904\u7406\u8fd9\u4e2a\u5305\u7684Chain\uff09\uff01<\/p>\n<p>\u5982\u679c\u5305\u7684\u76ee\u7684\u5730\u662f\u672c\u673aip,\u90a3\u4e48\u5305\u5411\u4e0a\u8d70\uff0c\u8d70\u5165INPUT\u94fe\u5904\u7406\uff0c\u7136\u540e\u8fdb\u5165LOCAL PROCESS,\u5982\u679c\u975e\u672c\u5730\uff0c\u90a3\u4e48\u5c31\u8fdb\u5165FORWARD\u94fe\u8fdb\u884c\u8fc7\u6ee4\uff0c\u6211\u4eec\u5728\u8fd9\u91cc\u5c31\u4e0d\u4ecb\u7ecdINPUT,OUTPUT\u7684\u5904\u7406\u4e86\uff0c\u56e0\u4e3a\u90a3\u4e3b\u8981\u662f\u5bf9\u4e8e\u672c\u673a\u5b89\u5168\u7684\u4e00\u79cd\u5904\u7406\uff0c\u6211\u4eec\u8fd9\u91cc\u4e3b\u8981\u8bf4\u5bf9\u8f6c\u53d1\u7684\u8fc7\u6ee4\u548cnat\u7684\u5b9e\u73b0\u3002<\/p>\n<p>\u8fd9\u91cc\u7684FORWARD\u6211\u7b80\u5355\u8bf4\u4e00\u4e0b\uff0c\u5f53linux\u6536\u5230\u4e86\u4e00\u4e2a\u00a0<strong>\u76ee\u7684ip\u5730\u5740\u4e0d\u662f\u672c\u5730\u7684\u5305<\/strong>\u00a0\uff0cLinux\u4f1a\u628a\u8fd9\u4e2a\u5305\u4e22\u5f03\uff0c\u56e0\u4e3a\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cLinux\u7684\u4e09\u5c42\u5305\u8f6c\u53d1\u529f\u80fd\u662f\u5173\u95ed\u7684\uff0c\u5982\u679c\u8981\u8ba9\u6211\u4eec\u7684linux\u5b9e\u73b0\u8f6c\u53d1\uff0c\u5219\u9700\u8981\u6253\u5f00\u8fd9\u4e2a\u8f6c\u53d1\u529f\u80fd\uff0c\u53ef\u4ee5 \u6539\u53d8\u5b83\u7684\u4e00\u4e2a\u7cfb\u7edf\u53c2\u6570\uff0c\u4f7f\u7528<code>sysctl net.ipv4.ip_forward=1<\/code>\u6216\u8005<code>echo \"1\" &gt; \/proc\/sys\/net\/ipv4\/ip_forward<\/code>\u547d\u4ee4\u6253\u5f00\u8f6c\u53d1\u529f\u80fd\u3002<\/p>\n<p>\u597d\u4e86\uff0c\u5728\u8fd9\u91cc\u6211\u4eec\u8ba9linux\u5141\u8bb8\u8f6c\u53d1\uff0c\u8fd9\u4e2a\u5305\u7684\u76ee\u7684\u5730\u5740\u4e5f\u4e0d\u662f\u672c\u673a\uff0c\u90a3\u4e48\u5b83\u5c06\u63a5\u7740\u8d70\u5165FORWARD\u94fe\uff0c\u5728FORWARD\u94fe\u91cc\u9762\uff0c\u6211\u4eec\u5c31\u53ef\u4ee5\u5b9a\u4e49\u8be6\u7ec6\u7684\u89c4\u5219\uff0c\u4e5f\u5c31\u662f\u662f\u5426\u5141\u8bb8\u4ed6\u901a\u8fc7\uff0c\u6216\u8005\u5bf9\u8fd9\u4e2a\u5305\u7684\u65b9\u5411\u6d41\u7a0b\u8fdb\u884c\u4e00\u4e9b\u6539\u53d8\uff0c\u8fd9\u4e5f\u662f\u6211\u4eec\u5b9e\u73b0\u8bbf\u95ee\u63a7\u5236\u7684\u5730\u65b9\uff0c\u8fd9\u91cc\u540c\u6837\u4e5f\u662fMangle_FORWARD\u7136\u540efilter_FORWARD,\u6211\u4eec\u64cd\u4f5c\u4efb\u4f55\u4e00\u4e2a\u94fe\u90fd\u4f1a\u5f71\u54cd\u5230\u8fd9\u4e2a\u5305\u7684\u547d\u8fd0\uff0c\u5728\u4e0b\u9762\u7684\u4ecb\u7ecd\u4e2d\uff0c\u6211\u4eec\u5c31\u5ffd\u7565\u6389mangle\u8868\uff0c\u6211\u4eec\u57fa\u672c\u7528\u4e0d\u5230\u64cd\u4f5c\u5b83\uff0c\u6240\u4ee5\u6211\u4eec\u5047\u8bbe\u5b83\u662f\u900f\u660e\u7684\u3002<\/p>\n<ul>\n<li>POSTROUTING(SNAT)<\/li>\n<\/ul>\n<p>\u5047\u8bbe\u8fd9\u4e2a\u5305\u88ab\u6211\u4eec\u7684\u89c4\u5219\u653e\u8fc7\u53bb\u4e86\uff0c\u4e5f\u5c31\u662fACCEPT\u4e86\uff0c\u5b83\u5c06\u8fdb\u5165POSTROUTING\u90e8\u5206\uff0c\u00a0<strong>\u6ce8\u610f\uff01\u8fd9\u91cc\u6211\u6ce8\u610f\u5230\u4e00\u4e2a\u7ec6\u8282\u95ee\u9898\uff0c\u4e5f\u5c31\u662f\u4e0a\u9762\u7684\u56fe\u4e2d\u6570\u636e\u5305\u8fc7\u4e86FORWARD\u94fe\u4e4b\u540e\u76f4\u63a5\u8fdb\u5165\u4e86POSTROUITNG\u94fe\uff0c\u6211\u89c9\u5f97\u8fd9\u4e2d\u95f4\u7f3a\u5c11\u4e00\u4e2a\u73af\u8282\uff0c\u4e5f\u5c31\u662froute box,\u5bf9\u4e8e\u8f6c\u53d1\u7684\u5305\u6765\u8bf4\uff0clinux\u540c\u6837\u9700\u8981\u5728\u9009\u8def\uff08\u8def\u7531\uff09\u4e4b\u540e\u624d\u80fd\u5c06\u5b83\u9001\u51fa\uff0c\u8fd9\u4e2a\u56fe\u5374\u6ca1\u6709\u6807\u660e\u8fd9\u4e00\u70b9\uff0c\u6211\u8ba4\u4e3a\u5b83\u662f\u5728\u8fc7\u4e86route box\u4e4b\u540e\u624d\u8fdb\u5165\u7684POSTROUITNG\uff0c\u5f53\u7136\u4e86\uff0c\u8fd9\u5bf9\u4e8e\u6211\u4eec\u8ba8\u8bbaiptables\u7684\u8fc7\u6ee4\u8f6c\u53d1\u6765\u8bf4\u4e0d\u662f\u5f88\u91cd\u8981\uff0c\u53ea\u662f\u6211\u89c9\u5f97\u6d41\u7a0b\u4e0a\u6709\u8fd9\u4e2a\u95ee\u9898\uff0c\u8fd8\u662f\u8981\u8bf4\u660e \u4e00\u4e0b\u3002<\/strong><\/p>\n<p>\u540c\u6837\u7684\uff0c\u6211\u4eec\u5728\u8fd9\u91cc\u4ece\u540d\u5b57\u5c31\u53ef\u4ee5\u770b\u51fa\uff0c\u8fd9\u4e2aPOSTROUTING\u94fe\u5e94\u8be5\u662f\u8def\u7531\u4e4b\u540e\u7684\u4e00\u4e2a\u94fe\uff0c\u4e5f\u5c31\u662f\u8fd9\u4e2a\u5305\u8981\u9001\u51fa\u8fd9\u53f0Linux\u7684 \u6700\u540e\u4e00\u4e2a\u73af\u8282\u4e86\uff0c\u8fd9\u4e5f\u662f\u6781\u5176\u91cd\u8981\u7684\u4e00\u4e2a\u73af\u8282\uff01\uff01\u8fd9\u4e2a\u65f6\u5019linux\u5df2\u7ecf\u5b8c\u6210(has done..<sup><small>_<\/small><\/sup>)\u4e86\u5bf9\u8fd9\u4e2a\u5305\u7684\u8def\u7531\uff08\u9009\u8def\u5de5\u4f5c\uff09\uff0c\u5df2\u7ecf\u627e\u5230\u4e86\u5408\u9002\u7684\u63a5\u53e3\u9001\u51fa\u8fd9\u4e2a\u5305\u4e86\uff0c\u5728\u8fd9\u4e2a\u94fe\u91cc\u9762\u6211\u4eec\u8981\u8fdb\u884c\u91cd\u8981\u7684\u64cd\u4f5c\uff0c\u5c31\u662f\u88abLinux\u79f0\u4e3a\u00a0<strong>SNAT<\/strong>\u00a0\u7684\u4e00\u4e2a\u52a8\u4f5c\uff0c\u4fee\u6539\u6e90ip\u5730\u5740\uff01\u4e3a\u4ec0\u4e48\u4fee\u6539\u6e90ip\u5730\u5740\uff1f\u5f88\u591a\u60c5\u51b5\u9700\u8981\u4fee\u6539\u6e90\u5730\u5740\u963f\uff0c\u6700\u5e38\u89c1\u7684\u5c31\u662f\u6211\u4eec\u5185\u7f51\u591a\u53f0\u673a\u5668\u9700\u8981\u5171\u4eab\u4e00\u4e2a\u6216\u51e0\u4e2a\u516c\u7f51ip\u8bbf\u95eeinternet,\u56e0\u4e3a\u6211\u4eec\u7684\u5185\u7f51\u5730\u5740\u662f\u79c1\u6709\u7684\uff0c\u5047\u5982\u5c31\u8ba9linux\u7ed9\u8def\u7531\u51fa\u53bb\uff0c\u6e90\u5730\u5740\u4e5f\u4e0d\u53d8\uff0c\u8fd9\u4e2a\u5305\u5e94\u8be5\u80fd\u8bbf\u95ee\u5230\u76ee\u7684\u5730\uff0c\u4f46\u662f\u5374\u56de\u4e0d\u6765\uff0c\u56e0\u4e3a internet\u4e0a\u7684N\u591a\u4e2a\u8def\u7531\u8282\u70b9\u4e0d\u4f1a\u8f6c\u53d1\u79c1\u6709\u5730\u5740\u7684\u6570\u636e\u5305\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u4e0d\u7528\u5408\u6cd5ip,\u6211\u4eec\u7684\u6570\u636e\u5305\u6709\u53bb\u65e0\u56de\u3002\u6709\u4eba\u4f1a\u8bf4\uff1a\u201c\u65e2\u7136\u662f\u8fd9\u6837\uff0c\u6211\u5c31\u4e0d\u7528\u79c1\u6709 ip\u4e86\uff0c\u6211\u81ea\u5df1\u5206\u914d\u81ea\u5df1\u5408\u6cd5\u7684\u5730\u5740\u4e0d\u884c\u5417\uff1f\u90a3\u6837\u5305\u5c31\u4f1a\u56de\u6765\u4e86\u5427\uff1f\u201d\u7b54\u6848\u662f\u5426\u5b9a\u7684\uff0cip\u5730\u5740\u662fICANN\u6765\u5206\u914d\u7684\uff0c\u4f60\u7684\u6570\u636e\u5305\u6216\u8bb8\u80fd\u53d1\u5230\u76ee\u7684\u5730\uff0c\u4f46\u662f\u56de\u6765\u7684 \u65f6\u5019\u4eba\u5bb6\u53ef\u4e0d\u4f1a\u8f6c\u5230\u4f60\u90a3\u91cc\uff0cinternet\u4e0a\u7684\u8def\u7531\u5668\u4e2d\u7684\u8def\u7531\u4fe1\u606f\u4f1a\u628a\u8fd9\u4e2a\u8fd4\u56de\u5305\u9001\u5230\u90a3\u4e2a\u5408\u6cd5\u7684\u83b7\u5f97ip\u7684\u5730\u65b9\u53bb\uff0c\u4f60\u540c\u6837\u6536\u4e0d\u5230,\u800c\u4f60\u8fd9\u79cd\u884c\u4e3a\u6709\u53ef\u80fd\u88ab\u5b9a\u4e49\u4e3a\u4e00\u79cdip\u6b3a\u9a97\uff0c\u5f88\u591a\u8bbe\u5907\u4f1a\u628a\u8fd9\u6837\u7684\u5305\u5728\u63a5\u5165\u7aef\u5c31\u7ed9\u6ee4\u6389\u4e86\uff0c\u53ef\u80fd\u90fd\u5230\u4e0d\u4e86\u4f60\u8981\u8bbf\u95ee\u7684\u90a3\u4e2a\u670d\u52a1\u5668\uff0c\u5475\u5475\u3002<\/p>\n<p>\u90a3\u4e48Linux\u5982\u4f55\u505aSNAT\u5462\uff1f\u6bd4\u5982\u4e00\u4e2a\u5185\u7f51\u768410.1.1.11\u7684pc\u8bbf\u95ee202.2.2.2\u7684\u4e00\u4e2aweb\u670d\u52a1\u5668\uff0clinux\u7684\u5185\u7f51\u63a5\u53e310.1.1.1\u5728\u6536\u5230\u8fd9\u4e2a\u5305\u4e4b\u540e\u628a\u539f\u6765\u7684 PC\u7684 ip10.1.1.11\u6539\u53d8\u4e3a60.1.1.1\u7684\u5408\u6cd5\u5730\u5740\u7136\u540e\u9001\u51fa\uff0c\u540c\u65f6\u5728\u81ea\u5df1\u7684ip_conntrack\u8868\u91cc\u9762\u505a\u4e00\u4e2a\u8bb0\u5f55,\u8bb0\u4f4f\u662f\u5185\u7f51\u7684\u54ea\u4e00\u4e2aip\u7684\u54ea \u4e2a\u7aef\u53e3\u8bbf\u95ee\u7684\u8fd9\u4e2aweb\u670d\u52a1\u5668\uff0c\u81ea\u5df1\u628a\u5b83\u7684\u6e90\u5730\u5740\u6539\u6210\u591a\u5c11\u4e86\uff0c\u7aef\u53e3\u6539\u6210\u591a\u5c11\u4e86\uff0c\u4ee5\u4fbf\u8fd9\u4e2aweb\u670d\u52a1\u5668\u8fd4\u56de\u6570\u636e\u5305\u7684\u65f6\u5019linux\u5c06\u5b83\u51c6\u786e\u7684\u9001\u56de\u7ed9\u53d1\u9001\u8bf7\u6c42 \u7684\u8fd9\u4e2apc.<\/p>\n<p>\u5927\u4f53\u7684\u6570\u636e\u8f6c\u53d1\u6d41\u7a0b\u6211\u4eec\u8bf4\u5b8c\u4e86,\u6211\u4eec\u770b\u770biptables\u4f7f\u7528\u4ec0\u4e48\u6837\u7684\u53c2\u6570\u6765\u5b8c\u6210\u8fd9\u4e9b\u64cd\u4f5c\u3002<\/p>\n<h2 id=\"toc_0.2\">\u6982\u5ff5\u7406\u89e3<\/h2>\n<p>\u5728\u63cf\u8ff0\u8fd9\u4e9b\u5177\u4f53\u7684\u64cd\u4f5c\u4e4b\u524d\uff0c\u6211\u8fd8\u8981\u8bf4\u51e0\u4e2a\u6211\u5bf9iptables\u7684\u6982\u5ff5\u7684\u7406\u89e3\uff08\u672a\u5fc5\u5b8c\u5168\u6b63\u786e\uff09\uff0c\u8fd9\u5c06\u6709\u52a9\u4e8e\u5927\u5bb6\u7406\u89e3\u8fd9\u4e9b\u89c4\u5219\uff0c\u4ee5\u5b9e\u73b0\u66f4\u7cbe\u786e\u7684\u63a7\u5236\u3002<\/p>\n<p>\u4e0a\u6587\u4e2d\u6211\u4eec\u63d0\u5230\u8fc7\uff0c\u5bf9\u5305\u7684\u63a7\u5236\u662f\u7531\u6211\u4eec\u5728\u4e0d\u540c\u7684Chain(\u94fe)\u4e0a\u9762\u6dfb\u52a0\u4e0d\u540c\u7684\u89c4\u5219\u6765\u5b9e\u73b0\u7684\uff0c\u6bd4\u5982\u6211\u4eec\u5bf9\u8fc7\u6ee4\u8868\uff08filter table\uff09\u6dfb\u52a0\u89c4\u5219\u6765\u6267\u884c\u5bf9\u5305\u7684\u64cd\u63a7\u3002\u90a3\u4e48\u65e2\u7136\u53eb\u94fe\uff0c\u4e00\u5b9a\u5c31\u662f\u4e00\u6761\u6216\u8005\u591a\u6761\u89c4\u5219\u7ec4\u6210\u7684\u4e86\uff0c\u8fd9\u65f6\u5c31\u6709\u4e00\u4e2a\u95ee\u9898\u4e86\uff0c\u5982\u679c\u591a\u4e2a\u89c4\u5219\u5bf9\u540c\u4e00\u79cd\u5305\u8fdb\u884c\u4e86\u5b9a\u4e49\uff0c\u4f1a\u53d1\u751f\u4ec0\u4e48\u4e8b\u60c5\u5462\uff1f\u00a0<strong>\u5728Chain\u4e2d\uff0c\u6240\u6709\u7684\u89c4\u5219\u90fd\u662f\u4ece\u4e0a\u5411\u4e0b\u6765\u6267\u884c\u7684<\/strong>\u00a0\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u5982\u679c\u5339\u914d\u4e86\u7b2c\u4e00\u884c\uff0c\u90a3\u4e48\u5c31\u6309\u7167\u7b2c\u4e00\u884c\u7684\u89c4\u5219\u6267\u884c\uff0c\u4e00\u884c\u4e00\u884c\u7684\u5f80\u4e0b\u627e\uff0c\u76f4\u5230\u627e\u5230 \u7b26\u5408\u8fd9\u4e2a\u7c7b\u578b\u7684\u5305\u7684\u89c4\u5219\u4e3a\u6b62\u3002\u5982\u679c\u627e\u4e86\u4e00\u904d\u6ca1\u6709\u627e\u5230\u7b26\u5408\u8fd9\u4e2a\u5305\u7684\u89c4\u5219\u600e\u4e48\u529e\u5462\uff1fitpables\u91cc\u9762\u6709\u4e00\u4e2a\u6982\u5ff5\uff0c\u5c31\u662f\u00a0<strong>Policy<\/strong>\u00a0\uff0c\u4e5f\u5c31\u662f\u7b56\u7565\u3002\u4e00\u8bf4\u8fd9\u4e2a\u4e1c\u897f\u5927\u5bb6\u53ef\u80fd\u5c31\u4f1a\u89c9\u5f97\u6bd4\u8f83\u9ebb\u70e6\uff0c\u4ec0\u4e48\u7b56\u7565\u963f\uff0c\u6211\u5bf9\u4e8e\u5b83\u7684\u7406\u89e3\u5c31\u662f\u6240\u8c13\u8fd9\u4e2a\u7b56\u7565\u5c31\u662fchain\u4e2d\u7684\u6700\u540e\u4e00\u6761\u89c4\u5219\uff0c\u4e5f\u5c31\u662f\u8bf4\u5982\u679c\u627e\u4e86\u4e00\u904d\u627e\u4e0d\u5230\u7b26\u5408\u5904\u7406\u8fd9\u4e2a\u5305\u7684\u89c4\u5219\uff0c\u5c31\u6309\u7167policy\u6765\u529e\u3002\u8fd9\u6837\u7406\u89e3\u8d77\u6765\u5c31\u5bb9\u6613\u591a\u4e86\u3002iptables \u4f7f\u7528-P\u6765\u8bbe\u7f6eChain\u7684\u7b56\u7565\u3002<\/p>\n<p>\u597d\u4e86\uff0c\u6211\u4eec\u8a00\u5f52\u6b63\u4f20\uff0c\u6765\u8bf4\u8bf4iptables\u5230\u5e95\u600e\u6837\u5b9e\u73b0\u5bf9\u5305\u7684\u63a7\u5236\u3002<\/p>\n<h3 id=\"toc_0.2.1\">\u94fe\u64cd\u4f5c<\/h3>\n<p>\u5148\u4ecb\u7ecd\u4e00\u4e0biptables\u5982\u4f55\u64cd\u4f5c\u94fe<\/p>\n<p>\u5bf9\u94fe\u7684\u64cd\u4f5c\u5c31\u90a3\u4e48\u51e0\u79cd\uff1a<\/p>\n<ul>\n<li>-I(\u63d2\u5165)<\/li>\n<li>-A(\u8ffd\u52a0)<\/li>\n<li>-R(\u66ff\u6362)<\/li>\n<li>-D\uff08\u5220\u9664\uff09<\/li>\n<li>-L\uff08\u5217\u8868\u663e\u793a\uff09<\/li>\n<\/ul>\n<p>\u8fd9\u91cc\u8981\u8bf4\u660e\u7684\u5c31\u662f-I\u5c06\u4f1a\u628a\u89c4\u5219\u653e\u5728\u7b2c\u4e00\u884c\uff0c-A\u5c06\u4f1a\u653e\u5728\u6700\u540e\u4e00\u884c\u3002<\/p>\n<p>\u6bd4\u5982\u6211\u4eec\u8981\u6dfb\u52a0\u4e00\u4e2a\u89c4\u5219\u5230filter\u8868\u7684FORWARD\u94fe\uff1a<\/p>\n<p><code>iptables -t filter -A FORWARD -s 10.1.1.11 -d 202.1.1.1 -j ACCEPT<\/code><\/p>\n<p>\u4e0a\u9762\u7684\u547d\u4ee4\u610f\u601d\u4e3a\uff1a\u8ffd\u52a0\u4e00\u4e2a\u89c4\u5219\u81f3filter\u8868\u4e2d\u7684FORWARD\u94fe\u5c3e\uff0c\u5141\u8bb8\uff08-j ACCEPT\uff09\u6e90\u5730\u5740\u4e3a10.1.1.11\u76ee\u7684\u5730\u5740\u4e3a202.1.1.1\u7684\u6570\u636e\u5305\u901a\u8fc7\u3002\u5176\u4e2d-t\u540e\u9762\u8ddf\u7684\u662f\u8868\u540d\uff0c\u5728-A\u540e\u9762\u8ddfChain\u540d\uff0c\u540e\u9762\u7684\u5c0f\u5199\u7684 -s\u4e3a\u6e90\u5730\u5740\uff0c-d\u4e3a\u76ee\u7684\u5730\u5740\uff0c-j\u4e3a\u5904\u7406\u65b9\u5411\u3002<\/p>\n<p>\u5728iptables\u4e2d\uff0c\u9ed8\u8ba4\u7684\u8868\u540d\u5c31\u662ffilter\uff0c\u6240\u4ee5\u8fd9\u91cc\u53ef\u4ee5\u7701\u7565-t filter\u76f4\u63a5\u5199\u6210:\u00a0<code>iptables -A FORWARD -s 10.1.1.11 -d 202.1.1.1 -j ACCEPT<\/code><\/p>\n<h3 id=\"toc_0.2.2\">\u5339\u914d\u53c2\u6570<\/h3>\n<p>iptables\u4e2d\u7684\u5339\u914d\u53c2\u6570\uff1a \u6211\u4eec\u5728\u8fd9\u91cc\u5c31\u4ecb\u7ecd\u51e0\u79cd\u5e38\u7528\u7684\u53c2\u6570\uff0c\u8be6\u7ec6\u5730\u7528\u6cd5\u53ef\u4ee5man iptables\u770b\u5b83\u7684\u8054\u673a\u6587\u6863\uff0c\u4f60\u4f1a\u6709\u610f\u5916\u7684\u6536\u83b7\u3002<\/p>\n<table>\n<tbody>\n<tr>\n<td>-s<\/td>\n<td>\u5339\u914d\u6e90\u5730\u5740<\/td>\n<\/tr>\n<tr>\n<td>-d<\/td>\n<td>\u5339\u914d\u76ee\u7684\u5730\u5740<\/td>\n<\/tr>\n<tr>\n<td>-p<\/td>\n<td>\u534f\u8bae\u5339\u914d<\/td>\n<\/tr>\n<tr>\n<td>-i<\/td>\n<td>\u5165\u63a5\u53e3\u5339\u914d<\/td>\n<\/tr>\n<tr>\n<td>-o<\/td>\n<td>\u51fa\u63a5\u53e3\u5339\u914d<\/td>\n<\/tr>\n<tr>\n<td>&#8211;sport\uff0c&#8211;dport<\/td>\n<td>\u6e90\u548c\u76ee\u7684\u7aef\u53e3\u5339\u914d<\/td>\n<\/tr>\n<tr>\n<td>-j<\/td>\n<td>\u8df3\u8f6c,\u4e5f\u5c31\u662f\u5305\u7684\u65b9\u5411<\/td>\n<\/tr>\n<tr>\n<td>!<\/td>\n<td>\u53d6\u53cd<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u5176\u4e2d\u8fd8\u6709\u4e00\u4e2a!\u53c2\u6570\uff0c\u4f7f\u7528!\u5c31\u662f\u53d6\u53cd\u7684\u610f\u601d\u3002\u4e0b\u9762\u6211\u4eec\u7b80\u5355\u4e3e\u51e0\u4e2a\u4f8b\u5b50\u4ecb\u7ecd\u4e00\u4e0b\u3002<\/p>\n<p>-s \u8fd9\u4e2a\u53c2\u6570\u5462\u5c31\u662f\u6307\u5b9a\u6e90\u5730\u5740\u7684\uff0c\u5982\u679c\u4f7f\u7528\u8fd9\u4e2a\u53c2\u6570\u4e5f\u5c31\u662f\u544a\u8bc9netfilter\uff0c\u5bf9\u4e8e\u7b26\u5408\u8fd9\u6837\u4e00\u4e2a\u6e90\u5730\u5740\u7684\u5305\u600e\u4e48\u53bb\u5904\u7406\uff0c\u53ef\u4ee5\u6307\u5b9a\u67d0\u4e00\u4e2a\u5355\u64adip\u5730\u5740\uff0c\u4e5f\u53ef\u4ee5\u6307\u5b9a\u4e00\u4e2a\u7f51\u7edc\uff0c\u5982\u679c\u5355\u4e2a\u7684ip\u5730\u5740\u5176\u5b9e\u9690\u542b\u4e86\u4e00\u4e2a32\u4f4d\u7684\u5b50\u7f51\u63a9\u7801\uff0c\u6bd4\u5982-s 10.1.1.11 \u5176\u5b9e\u5c31\u662f-s 10.1.1.11\/32\uff0c\u540c\u6837\u6211\u4eec\u53ef\u4ee5\u6307\u5b9a\u4e0d\u540c\u7684\u63a9\u7801\u7528\u4ee5\u5b9e\u73b0\u6e90\u7f51\u7edc\u5730\u5740\u7684\u89c4\u5219\uff0c\u6bd4\u5982\u4e00\u4e2aC\u7c7b\u5730\u5740\u6211\u4eec\u53ef\u4ee5\u7528-s 10.1.1.0\/24\u6765\u6307\u5b9a\u3002<\/p>\n<p>-d\u53c2\u6570\u4e0e-s\u683c\u5f0f\u4e00\u6837\u3002<\/p>\n<p>-i\u53c2\u6570\u662f\u6307\u5b9a\u5165\u63a5\u53e3\u7684\u7f51\u7edc\u63a5\u53e3\uff0c\u6bd4\u5982\u6211\u4ec5\u4ec5\u5141\u8bb8\u4eceeth3\u63a5\u53e3\u8fc7\u6765\u7684\u5305\u901a\u8fc7FORWARD\u94fe\uff0c\u5c31\u53ef\u4ee5\u8fd9\u6837\u6307\u5b9a<code>iptables -A FORWARD -i eth3 -j ACCEPT<\/code><\/p>\n<p>-o\u662f\u51fa\u63a5\u53e3,\u4e0e\u4e0a\u540c\u3002<\/p>\n<p>\u6211\u4eec\u4e0b\u9762\u7528\u4e00\u4e9b\u7b80\u5355\u7684\u5b9e\u4f8b\u6765step by step\u770b\u770biptables\u7684\u5177\u4f53\u914d\u7f6e\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"toc_0.3\">\u5b9e\u4f8b\u4e00\uff1a\u7b80\u5355\u7684nat\u8def\u7531\u5668<\/h2>\n<ul>\n<li>\u73af\u5883\u4ecb\u7ecd\n<ul>\n<li>linux 2.4 +<\/li>\n<li>2\u4e2a\u7f51\u7edc\u63a5\u53e3<\/li>\n<li>Lan\u53e3:10.1.1.254\/24 eth0<\/li>\n<li>Wan\u53e3:60.1.1.1\/24 eth1<\/li>\n<li>\u76ee\u7684\uff1a\u5b9e\u73b0\u5185\u7f51\u4e2d\u7684\u8282\u70b9\uff0810.1.1.0\/24\uff09\u53ef\u63a7\u7684\u8bbf\u95eeinternet\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>\u9996\u5148\u5c06Lan\u7684\u8282\u70b9pc\u7684\u7f51\u5173\u6307\u541110.1.1.254\u3002<\/p>\n<p>\u786e\u5b9a\u4f60\u7684linux\u7684ip\u914d\u7f6e\u65e0\u8bef\uff0c\u53ef\u4ee5\u6b63\u786e\u7684ping\u901a\u5185\u5916\u7684\u5730\u5740\u3002\u540c\u65f6\u7528route\u547d\u4ee4\u67e5\u770blinux\u7684\u672c\u5730\u8def\u7531\u8868\uff0c\u786e\u8ba4\u6307\u5b9a\u4e86\u53ef\u7528\u7684ISP\u63d0\u4f9b\u7684\u9ed8\u8ba4\u7f51\u5173\u3002<\/p>\n<p>\u6253\u5f00linux\u7684\u8f6c\u53d1\u529f\u80fd\uff1a<code>sysctl net.ipv4.ip_forward=1<\/code><\/p>\n<p>\u5c06FORWARD\u94fe\u7684\u7b56\u7565\u8bbe\u7f6e\u4e3aDROP\uff0c\u8fd9\u6837\u505a\u7684\u76ee\u7684\u662f\u505a\u5230\u5bf9\u5185\u7f51ip\u7684\u63a7\u5236\uff0c\u4f60\u5141\u8bb8\u54ea\u4e00\u4e2a\u8bbf\u95eeinternet\u5c31\u53ef\u4ee5\u589e\u52a0\u4e00\u4e2a\u89c4\u5219\uff0c\u4e0d\u5728\u89c4\u5219\u4e2d\u7684ip\u5c06\u65e0\u6cd5\u8bbf\u95eeinternet.<\/p>\n<p><code>iptables -P FORWARD DROP<\/code><\/p>\n<p>\u8fd9\u6761\u89c4\u5219\u89c4\u5b9a\u5141\u8bb8\u4efb\u4f55\u5730\u5740\u5230\u4efb\u4f55\u5730\u5740\u7684\u786e\u8ba4\u5305\u548c\u5173\u8054\u5305\u901a\u8fc7\u3002\u4e00\u5b9a\u8981\u52a0\u8fd9\u4e00\u6761\uff0c\u5426\u5219\u4f60\u53ea\u5141\u8bb8lan IP\u8bbf\u95ee\u6ca1\u6709\u7528\uff0c\u81f3\u4e8e\u4e3a\u4ec0\u4e48\uff0c\u4e0b\u9762\u6211\u4eec\u518d\u8be6\u7ec6\u8bf4\u3002<\/p>\n<p><code>iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT<\/code><\/p>\n<p>\u8fd9\u6761\u89c4\u5219\u505a\u4e86\u4e00\u4e2aSNAT\uff0c\u4e5f\u5c31\u662f\u6e90\u5730\u5740\u8f6c\u6362\uff0c\u5c06\u6765\u81ea10.1.1.0\/24\u7684\u5730\u5740\u8f6c\u6362\u4e3a60.1.1.1<\/p>\n<p>(Deven\uff1a\u56e0\u4e3a\u662f\u8ba9\u5185\u7f51\u4e0a\u7f51\uff0c\u56e0\u6b64\u5bf9\u4e8e\u4ee3\u7406\u670d\u52a1\u5668\u800c\u8a00POSTROUTING\uff08\u7ecf\u8fc7\u8def\u7531\u4e4b\u540e\u7684\u5305\u5e94\u8be5\u8981\u628a\u6e90\u5730\u5740\u6539\u53d8\u4e3a60.1.1.1\uff0c\u5426\u5219\u5305\u65e0\u6cd5\u8fd4\u56de\uff09)<\/p>\n<p><code>iptables -t nat -A POSTROUTING -s 10.1.1.0\/24 -j SNAT --to 60.1.1.1<\/code><\/p>\n<p>\u6709\u8fd9\u51e0\u6761\u89c4\u5219\uff0c\u4e00\u4e2a\u7b80\u5355\u7684nat\u8def\u7531\u5668\u5c31\u5b9e\u73b0\u4e86\u3002\u8fd9\u65f6\u4f60\u53ef\u4ee5\u5c06\u5141\u8bb8\u8bbf\u95ee\u7684ip\u6dfb\u52a0\u81f3FORWARD\u94fe\uff0c\u4ed6\u4eec\u5c31\u80fd\u8bbf\u95eeinternet\u4e86\u3002<\/p>\n<p>\u6bd4\u5982\u6211\u60f3\u8ba910.1.1.9\u8fd9\u4e2a\u5730\u5740\u8bbf\u95eeinternet,\u90a3\u4e48\u4f60\u5c31\u52a0\u5982\u4e0b\u7684\u547d\u4ee4\u5c31\u53ef\u4ee5\u4e86\u3002<\/p>\n<p><code>iptables -A FORWARD -s 10.1.1.9 -j ACCEPT<\/code><\/p>\n<p>\u4e5f\u53ef\u4ee5\u7cbe\u786e\u63a7\u5236\u4ed6\u7684\u8bbf\u95ee\u5730\u5740,\u6bd4\u5982\u6211\u5c31\u5141\u8bb810.1.1.99\u8bbf\u95ee3.3.3.3\u8fd9\u4e2aip<\/p>\n<p><code>iptables -A FORWARD -s 10.1.1.99 -d 3.3.3.3 -j ACCEPT<\/code><\/p>\n<p>\u6216\u8005\u53ea\u5141\u8bb8\u4ed6\u4eec\u8bbf\u95ee80\u7aef\u53e3\u3002<\/p>\n<p><code>iptables -A FORWARD -s 10.1.1.0\/24 -p tcp --dport http -j ACCEPT<\/code><\/p>\n<p>\u66f4\u591a\u7684\u63a7\u5236\u53ef\u4ee5\u81ea\u5df1\u7075\u6d3b\u53bb\u505a,\u6216\u8005\u67e5\u9605iptables\u7684\u8054\u673a\u6587\u6863\u3002<\/p>\n<h2 id=\"toc_0.4\">\u5b9e\u4f8b\u4e8c\uff1a\u7aef\u53e3\u8f6c\u53d1<\/h2>\n<ul>\n<li>\u73af\u5883\u4ecb\u7ecd\n<ul>\n<li>linux 2.4 +<\/li>\n<li>2\u4e2a\u7f51\u7edc\u63a5\u53e3<\/li>\n<li>Lan\u53e3:10.1.1.254\/24 eth0<\/li>\n<li>Lan\u5185web server: 10.1.1.1:80<\/li>\n<li>Lan\u5185ftp server: 10.1.1.2:21<\/li>\n<li>Wan\u53e3:60.1.1.1\/24 eth1<\/li>\n<li>\u76ee\u7684\uff1a\u5bf9\u5185\u90e8server\u8fdb\u884c\u7aef\u53e3\u8f6c\u53d1\u5b9e\u73b0internet\u7528\u6237\u8bbf\u95ee\u5185\u7f51\u670d\u52a1\u5668<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>\u540c\u6837\u786e\u8ba4\u4f60\u7684linux\u7684\u5404\u9879\u914d\u7f6e\u6b63\u5e38\uff0c\u80fd\u591f\u8bbf\u95ee\u5185\u5916\u7f51\u3002<\/p>\n<pre>iptables -P FORWARD DROP\r\niptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT\r\n<\/pre>\n<p>\u4e5f\u9700\u8981\u52a0\u5165\u786e\u8ba4\u5305\u548c\u5173\u8054\u5305\u7684\u5141\u8bb8\u901a\u8fc7<\/p>\n<p>\u5982\u679c\u4f60\u8981\u628a\u8bbf\u95ee60.1.1.1:80\u7684\u6570\u636e\u5305\u8f6c\u53d1\u5230Lan\u5185web server,\u7528\u4e0b\u9762\u7684\u547d\u4ee4<\/p>\n<pre>iptables -t nat -A PREROUTING -d 60.1.1.1 -p tcp --dport 80 -j DNAT --to 10.1.1.1:80\r\n<\/pre>\n<p>ftp\u670d\u52a1\u4e5f\u540c\u6837\uff0c\u547d\u4ee4\u5982\u4e0b\uff1a<\/p>\n<pre>iptables -t nat -A PREROUTING -d 60.1.1.1 -p tcp --dport 21 -j DNAT --to 10.1.1.2:21\r\n<\/pre>\n<p>\u597d\u4e86\uff0c\u547d\u4ee4\u5b8c\u6210\u4e86\uff0c\u7aef\u53e3\u8f6c\u53d1\u4e5f\u505a\u5b8c\u4e86\uff0c\u672c\u4f8b\u80fd\u4e0d\u80fd\u8f6c\u53d1\u5462\uff1f\u4e0d\u80fd\uff0c\u4e3a\u4ec0\u4e48\u5462\uff1f\u6211\u4e0b\u9762\u8be6\u7ec6\u5206\u6790\u4e00\u4e0b\u3002<\/p>\n<p>\u5bf9\u4e8eiptables\u597d\u50cf\u5f80\u5916\u8bbf\u95ee\u7684\u914d\u7f6e\u6bd4\u8f83\u5bb9\u6613\uff0c\u800c\u5bf9\u5185\u7684\u8f6c\u53d1\u4f3c\u4e4e\u5c31\u6709\u4e00\u4e9b\u95ee\u9898\u4e86\uff0c\u5728\u4e00\u5f00\u59cb\u7684\u65f6\u5019\u6211\u5c31\u5148\u8bf4\u4e86\u4e00\u4e9b\u5173\u4e8enetfilter\u7684\u6d41\u7a0b\u95ee\u9898\uff0c\u90a3\u4e48\u6211\u5c31\u7b80\u5355\u8bf4\u8bf4\u505a\u4e86\u8fd9\u4e9b\u914d\u7f6e\u4e4b\u540e\u4e3a\u4ec0\u4e48\u6709\u53ef\u80fd\u8fd8\u4e0d\u884c\u5462\uff1f<\/p>\n<p>\u80fd\u5f15\u8d77\u8fd9\u4e2a\u914d\u7f6e\u5931\u8d25\u7684\u539f\u56e0\u6709\u5f88\u591a\uff0c\u6211\u4eec\u4e00\u4e2a\u4e2a\u7684\u6765\u8bf4\uff1a<\/p>\n<p>\u7b2c\u4e00\uff0c\u672c\u4f8b\u4e2d\uff0c\u6211\u4eec\u7684FORWARD\u7b56\u7565\u662fDROP,\u90a3\u4e48\u4e5f\u5c31\u662f\u8bf4\uff0c\u6ca1\u6709\u7b26\u5408\u89c4\u5219\u7684\u5305\u5c06\u88ab\u4e22\u5f03\uff0c\u4e0d\u7ba1\u5185\u5230\u5916\u8fd8\u662f\u5916\u5230\u5185\uff0c\u6211\u4eec\u5728\u8fd9\u91cc\u4f9d\u7136\u4e0d\u8ba8\u8bba\u90a3\u4e2a\u786e\u8ba4\u5305\u548c\u5173\u8054\u5305\u7684\u95ee\u9898\uff0c\u6211\u4eec\u4e0d\u7528\u8003\u8651\u4ed6\u7684\u95ee\u9898\uff0c\u4e0b\u9762\u6211\u4f1a\u8be6\u7ec6\u8bf4\u4e00\u4e0b\u8fd9\u4e2a\u4e1c\u897f\uff0c\u90a3\u4e48\u5982\u4f55\u8ba9\u672c\u4f8b\u53ef\u4ee5\u6210\u529f\u5462\uff1f\u52a0\u5165\u4e0b\u9762\u7684\u89c4\u5219\u3002<\/p>\n<pre>iptables -A FORWARD -d 10.1.1.1 -p tcp --dport 80 -j ACCEPT\r\niptables -A FORWARD -d 10.1.1.2 -p tcp --dport 21 -j ACCEPT\r\n<\/pre>\n<p>\u6709\u6ca1\u6709\u89c9\u5f97\u6709\u4e00\u4e9b\u6655\uff1f\u4e3a\u4ec0\u4e48\u76ee\u7684\u5730\u5740\u662f10.xxx\u800c\u4e0d\u662f60.xxx\u4eba\u5bb6internet\u7528\u6237\u4e0d\u662f\u8bbf\u95ee\u768460.xxx\u5417\uff1f\u5475\u5475\uff0c\u56de\u5230\u4e0a\u9762\u770b\u770b\u90a3\u4e2a\u56fe\u5427\uff0cFORWARD\u94fe\u5728\u4ec0\u4e48\u4f4d\u7f6e\u4e0a\uff0c\u5b83\u662f\u5728PREROUTING\u4e4b\u540e\uff0c\u4e5f\u5c31\u662f\u8bf4\u5f53\u8fd9\u4e2a\u5305\u5230\u8fbeFORWARD\u94fe\u7684\u65f6\u5019\uff0c\u76ee\u7684\u5730\u5740\u5df2\u7ecf\u53d8\u621010.xxx\u4e86\uff0c\u5047\u5982internet\u7528\u6237\u7684\u8bf7\u6c42\u662f\u8fd9\u6837202.1.1.1:1333&#8211;&gt;60.1.1.1:80\uff0c\u5728\u7ecf\u8fc7\u4e86\u6211\u4eec\u7684PREROUTING\u94fe\u4e4b\u540e\u5c06\u53d8\u6210 202.1.1.1:1333&#8211;&gt;10.1.1.1:80,\u8fd9\u4e2a\u65f6\u5019\u5982\u679c\u4f60\u8bbe\u7f6e\u4e00\u4e2a\u76ee\u7684\u5730\u5740\u4e3a60.xxx\u7684\u89c4\u5219\u6709\u7528\u5417\uff1f\u5475\u5475\uff0c\u8fd9\u662f\u95ee\u9898\u4e00\u3002\u8fd9\u4e2a\u65f6\u5019\u5e94\u8be5\u53ef\u4ee5\u5b8c\u6210\u7aef\u53e3\u8f6c\u53d1\u7684\u8bbf\u95ee\u4e86\uff0c\u4f46\u662f\u6709\u4e00\u4e9b\u65f6\u5019\u8fd8\u662f\u4e0d\u884c\uff1f\u4e3a\u4ec0\u4e48\uff1f\u770b\u95ee\u9898\u4e8c\u3002<\/p>\n<p>\u7b2c\u4e8c\uff0c\u5185\u7f51server\u7684ip\u914d\u7f6e\u95ee\u9898\uff0c\u8fd9\u91cc\u6211\u4eec\u4ee5web server\u4e3a\u4f8b\u8bf4\u660e\u4e00\u4e0b\uff08ftp\u60c5\u51b5\u6709\u4e00\u4e9b\u7279\u6b8a\uff0c\u4e0b\u9762\u6211\u4eec\u518d\u8be6\u7ec6\u8ba8\u8bba\uff0c\u8bf4\u786e\u8ba4\u5305\u548c\u5173\u8054\u5305\u7684\u65f6\u5019\u8ba8\u8bba\u8fd9\u4e2a\u95ee\u9898\uff09\uff0c\u4e0a\u9762\u8bf4\u5230\uff0c\u6709\u7684\u65f6\u5019\u53ef\u4ee5\u8bbf\u95ee\u4e86\uff0c\u6709\u7684\u65f6\u5019\u5374\u4e0d\u884c\uff0c\u5c31\u662f\u8fd9\u4e2aweb server\u7684ip\u8bbe\u7f6e\u95ee\u9898\u4e86\uff0c\u5982\u679cweb server\u6ca1\u6709\u6307\u5b9a\u9ed8\u8ba4\u7684\u7f51\u5173\uff0c\u90a3\u4e48\u5728\u4f5c\u4e86\u4e0a\u9762\u7684\u914d\u7f6e\u4e4b\u540e\uff0cweb server\u4f1a\u6536\u5230internet\u7684\u8bf7\u6c42\uff0c\u4f46\u662f\uff0c\u4ed6\u4e0d\u77e5\u9053\u5f80\u54ea\u91cc\u56de\u554a\uff0c\u4eba\u5bb6\u7684\u672c\u5730\u8def\u7531\u8868\u4e0d\u77e5\u9053\u4f60\u90a3\u4e2ainternet\u7684ip,202.1.1.1\u8be5\u600e\u4e48\u8d70\u3002\u5982\u679c\u4f60\u4f7f\u7528\u622a\u5305\u5de5\u5177\u5728web server\u4e0a\u9762\u5bdf\u770b\uff0c\u4f60\u4f1a\u53d1\u73b0server\u6536\u5230\u4e86\u6765\u81ea202.1.1.1:1333&#8211;&gt;10.1.1.1:80\u7684\u8bf7\u6c42\uff0c\u7531\u4e8e\u4f60\u6ca1\u6709\u7ed9web server\u914d\u7f6e\u9ed8\u8ba4\u7f51\u5173\uff0c\u5b83\u4e0d\u77e5\u9053\u600e\u4e48\u56de\u53bb\uff0c\u6240\u4ee5\u5c31\u51fa\u73b0\u4e86\u4e0d\u901a\u7684\u60c5\u51b5\u3002\u600e\u4e48\u529e\u5462\uff1f\u4e24\u4e2a\u89e3\u51b3\u65b9\u6cd5\uff1a<\/p>\n<p>\u4e00\u5c31\u662f\u7ed9\u8fd9\u4e2aserver\u914d\u7f6e\u4e00\u4e2a\u9ed8\u8ba4\u7f51\u5173\uff0c\u5f53\u7136\u8981\u6307\u5411\u8fd9\u4e2a\u914d\u7f6e\u7aef\u53e3\u8f6c\u53d1\u7684linux,\u672c\u4f8b\u662f10.1.1.254,\u914d\u7f6e\u597d\u4e86\uff0c\u5c31\u4e00\u5b9a\u80fd\u8bbf\u95ee\u4e86\u3002\u6709\u4e00\u4e2a\u7591\u95ee\uff1f\u96be\u9053\u4e0d\u9700\u8981\u5728FORWARD\u94fe\u4e0a\u9762\u8bbe\u7f6e\u4e00\u4e2a\u5141\u8bb8web server\u7684ip\u5730\u5740\u8bbf\u95ee\u5916\u7f51\u7684\u89c4\u5219\u5417\uff1f\u5b83\u7684\u5305\u80fd\u51fa\u53bb\uff1f\u7b54\u6848\u662f\u80af\u5b9a\u7684\uff0c\u80fd\u51fa\u53bb\u3002\u56e0\u4e3a\u6211\u4eec\u90a3\u4e00\u6761\u5141\u8bb8\u786e\u8ba4\u5305\u4e0e\u5173\u8054\u5305\u7684\u89c4\u5219\uff0c\u5426\u5219\u5b83\u662f\u51fa\u4e0d\u53bb\u7684\u3002<\/p>\n<p>\u7b2c\u4e8c\u79cd\u65b9\u6cd5\uff0c\u6bd4\u8f83\u9ebb\u70e6\u4e00\u4e9b\uff0c\u4f46\u662f\u5bf9\u670d\u52a1\u5668\u6765\u8bf4\u8fd9\u6837\u4f3c\u4e4e\u66f4\u5b89\u5168\u4e00\u4e9b\u3002\u65b9\u6cd5\u5c31\u662f\u5bf9\u8fd9\u4e2a\u5305\u518d\u4f5c\u4e00\u6b21SNAT\uff0c\u4e5f\u5c31\u662f\u5728POSTROUTING\u94fe\u4e0a\u6dfb\u52a0\u89c4\u5219\u3002\u547d\u4ee4\u5982\u4e0b\uff1a<\/p>\n<p><code>iptables -t nat -A POSTROUTING -d 10.1.1.1 -p tcp --dport 80 -j SNAT --to 10.1.1.254<\/code><\/p>\n<p>ftp \u7684\u65b9\u6cd5\u76f8\u540c\u3002\u8fd9\u6761\u547d\u4ee4\u4e0d\u592a\u597d\u61c2\uff1f\uff1f\u5176\u5b9e\u5f88\u7b80\u5355\uff0c\u5982\u679c\u4f7f\u7528\u8fd9\u6761\u547d\u4ee4\uff0c\u90a3\u4e48\u4f60\u7684web server\u4e0d\u9700\u8981\u518d\u8bbe\u7f6e\u9ed8\u8ba4\u7f51\u5173\uff0c\u5c31\u80fd\u6536\u5230\u8fd9\u4e2a\u8bf7\u6c42\uff0c\u53ea\u8981\u4ed6\u548clinux\u7684lan ip\u5730\u5740\u662f\u80fd\u4e92\u8bbf\u7684\uff08\u4e5f\u5c31\u662f\u8bf4web server\u548cLinux\u7684Lan ip\u5728\u4e00\u4e2a\u5e7f\u64ad\u57df\uff09\uff0c\u6211\u4eec\u5728\u6839\u636e\u4e0a\u9762\u7684netfilter\u6d41\u7a0b\u56fe\u6765\u5206\u6790\u8fd9\u4e2a\u5305\u5230\u5e95\u88ab\u6211\u4eec\u600e\u4e48\u6837\u4e86\uff1a<\/p>\n<ul>\n<li>\u9996\u5148\u4e00\u4e2a\u8bf7\u6c42202.1.1.1:1333&#8211;&gt; 60.1.1.1:80\u88ablinux\u6536\u5230\u4e86\uff0c\u8fdb\u5165PREROUTING\uff1b<\/li>\n<li>\u53d1\u73b0\u4e00\u4e2a\u89c4\u5219<code>iptables -t nat -A PREROUTING -d 60.1.1.1 -p tcp --dport 80 -j DNAT --to 10.1.1.1:80<\/code>\u7b26\u5408\uff0c\u597d\u4e86\uff0c\u6539\u4f60\u7684\u76ee\u7684\u5730\u5740\uff0c\u4e8e\u662f\u8fd9\u4e2a\u5305\u53d8\u6210\u4e86202.1.1.1:1333&#8211;&gt;10.1.1.1:80\uff0c\u7ee7\u7eed\u5f80\u524d\u8d70\uff1b<\/li>\n<li>\u8fdb\u5165FORWARD\u94fe\uff0cokay,\u4e5f\u6709\u4e00\u6761\u89c4\u5219\u5141\u8bb8\u901a\u8fc7<code>iptables -A FORWARD -d 10.1.1.1 -p tcp --dport 80 -j ACCEPT<\/code>\uff1b<\/li>\n<li>\u8fdb\u5165route box\u9009\u8def\uff0c\u627e\u5230\u5408\u9002\u7684\u8def\u5f84\u4e86\uff0c\u7ee7\u7eed\u8fdb\u5165POSTROUTING\u94fe\uff1b<\/li>\n<li>\u8036\uff1f\u53c8\u53d1\u73b0\u4e00\u4e2a\u7b26\u5408\u7684\u89c4\u5219<code>iptables -t nat -A POSTROUTING -d 10.1.1.1 -p tcp --dport 80 -j SNAT --to 10.1.1.254<\/code>,\u539f\u6765\u662f\u4e00\u4e2aSNAT,\u6539\u4f60\u7684\u6e90\u5730\u5740\uff0c\u4e8e\u662f\u8fd9\u4e2a\u5305\u53d8\u6210\u4e8610.1.1.254:xxxx&#8211;&gt;10.1.1.1:80\u3002\u4e3a\u4ec0\u4e48\u7528xxxx\u4e86\uff0c\u8fd9\u91cc\u7684\u7aef\u53e3\u662f\u968f\u673a\u7684\uff0c\u6211\u4e5f\u4e0d\u77e5\u9053\u4f1a\u662f\u4ec0\u4e48\u3002<\/li>\n<li>\u800c\u6574\u4e2a\u7684\u4e24\u6b21\u53d8\u5316\u7684\u8fc7\u7a0b\u90fd\u4f1a\u8bb0\u5f55\u5728linux\u7684ip_conntrack\u4e2d\uff1b<\/li>\n<li>\u5f53web server\u6536\u5230\u8fd9\u4e2a\u5305\u7684\u65f6\u5019\uff0c\u53d1\u73b0\uff0c\u539f\u6765\u662f\u4e00\u4e2a\u5185\u7f51\u81ea\u5df1\u5144\u5f1f\u6765\u7684\u8bf7\u6c42\u963f\uff0c\u53c8\u5728\u4e00\u4e2a\u5e7f\u64ad\u57df\uff0c\u4e0d\u7528\u627e\u7f51\u5173\uff0c\u628a\u8fd4\u56de\u5305\u76f4\u63a5\u6254\u7ed9\u4ea4\u6362\u673a\u4e86\uff1b<\/li>\n<li>linux\u5728\u6536\u5230\u8fd4\u56de\u5305\u4e4b\u540e\uff0c\u4f1a\u6839\u636e\u4ed6\u7684ip_conntrack\u4e2d\u7684\u6761\u76ee\u8fdb\u884c\u4e24\u6b21\u53d8\u6362\uff0c\u8fd4\u56de\u771f\u6b63\u7684internet\u7528\u6237\uff0c\u4e8e\u662f\u5b8c\u6210\u8fd9\u4e00\u6b21\u7684\u8bbf\u95ee\u3002<\/li>\n<\/ul>\n<p>\u770b\u4e86\u4e0a\u9762\u7684\u4e24\u4e2a\u4f8b\u5b50\uff0c\u4e0d\u77e5\u9053\u5927\u5bb6\u662f\u5426\u6e05\u695a\u4e86iptables\u7684\u8f6c\u53d1\u6d41\u7a0b\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u6709\u6240\u5e2e\u52a9\u3002<\/p>\n<h2 id=\"toc_0.5\">\u72b6\u6001\u673a\u5236<\/h2>\n<p>\u4e0b\u9762\u6211\u4eec\u5c31\u8bf4\u8bf4\u6211\u4e00\u76f4\u5728\u4e0a\u9762\u63d0\u5230\u7684\u5173\u4e8e\u90a3\u4e2aESTABLISHED,RELATED\u7684\u89c4\u5219\u662f\u600e\u4e48\u56de\u4e8b\uff0c\u5230\u5e95\u6709\u4ec0\u4e48\u7528\u5904\u3002<\/p>\n<p>\u8bf4\u8fd9\u4e2a\u4e1c\u897f\u5c31\u8981\u7b80\u5355\u8bf4\u4e00\u4e0b\u7f51\u7edc\u7684\u6570\u636e\u901a\u8baf\u7684\u65b9\u5f0f\uff0c\u6211\u4eec\u77e5\u9053\uff0c\u7f51\u7edc\u7684\u8bbf\u95ee\u662f\u53cc\u5411\u7684\uff0c\u4e5f\u5c31\u662f\u8bf4\u4e00\u4e2aClient\u4e0eServer\u4e4b\u95f4\u5b8c\u6210\u6570\u636e\u4ea4\u6362\u9700\u8981\u53cc\u65b9\u7684\u53d1\u5305\u4e0e\u6536\u5305\u3002\u5728netfilter\u4e2d\uff0c\u6709\u51e0\u79cd\u72b6\u6001\uff0c\u4e5f\u5c31\u662f<code>new, established,related,invalid<\/code>\u3002<\/p>\n<p>\u5f53\u4e00\u4e2a\u5ba2\u6237\u7aef\uff0c\u5728\u672c\u6587\u4f8b\u4e00\u4e2d\uff0c\u5185\u7f51\u7684\u4e00\u53f0\u673a\u5668\u8bbf\u95ee\u5916\u7f51\uff0c\u6211\u4eec\u8bbe\u7f6e\u4e86\u89c4\u5219\u5141\u8bb8\u4ed6\u51fa\u53bb\uff0c\u4f46\u662f\u6ca1\u6709\u8bbe\u7f6e\u5141\u8bb8\u56de\u6765\u7684\u89c4\u5219\u963f\uff0c\u600e\u4e48\u5b8c\u6210\u8bbf\u95ee\u5462\uff1f\u8fd9\u5c31\u662fnetfilter\u7684\u00a0<strong>\u72b6\u6001\u673a\u5236<\/strong>\u00a0\uff0c\u5f53\u4e00\u4e2alan\u7528\u6237\u901a\u8fc7\u8fd9\u4e2alinux\u8bbf\u95ee\u5916\u7f51\u7684\u65f6\u5019\uff0c\u5b83\u53d1\u9001\u4e86\u4e00\u4e2a\u8bf7\u6c42\u5305\uff0c\u8fd9\u4e2a\u5305\u7684\u72b6\u6001\u662fnew,\u5f53\u5916\u7f51\u56de\u5305\u7684\u65f6\u5019\u4ed6\u7684\u72b6\u6001\u5c31\u662festablished,\u6240\u4ee5\uff0clinux\u77e5\u9053\uff0c\u54e6\uff0c\u8fd9\u4e2a\u5305\u662f\u6211\u7684\u5185\u7f51\u7684\u4e00\u53f0\u673a\u5668\u53d1\u51fa\u53bb\u7684\u5e94\u7b54\u5305\uff0c\u4ed6\u5c31\u653e\u884c\u4e86\u3002<\/p>\n<p>\u800c\u5916\u7f51\u8bd5\u56fe\u5bf9\u5185\u53d1\u8d77\u4e00\u4e2a\u65b0\u7684\u8fde\u63a5\u7684\u65f6\u5019\uff0c\u4ed6\u7684\u72b6\u6001\u662fnew,\u6240\u4ee5linux\u538b\u6839\u4e0d\u53bb\u7406\u4f1a\u5b83\u3002\u8fd9\u5c31\u662f\u6211\u4eec\u4e3a\u4ec0\u4e48\u8981\u52a0\u8fd9\u4e00\u53e5\u7684\u539f\u56e0\u3002<\/p>\n<p>\u8fd8\u6709\u90a3\u4e2arelated,\u4ed6\u662f\u4e00\u4e2a\u5173\u8054\u72b6\u6001\uff0c\u4ec0\u4e48\u4f1a\u7528\u5230\u5462\uff1ftftp,ftp\u90fd\u4f1a\u7528\u5230\uff0c\u56e0\u4e3a\u4ed6\u4eec\u7684\u4f20\u8f93\u673a\u5236\u51b3\u5b9a\u4e86\uff0c\u5b83\u4e0d\u50cfhttp\u8bbf\u95ee\u90a3\u6837\uff0c<code>Client_IP: port--&gt;server:80<\/code>\u7136\u540e<code>server:80--&gt;Client_IP:port<\/code>\uff0cftp\u4f7f\u7528tcp21\u5efa\u7acb\u8fde\u63a5\uff0c\u4f7f\u752820\u7aef\u53e3\u53d1\u9001\u6570\u636e\uff0c\u5176\u4e2d\u53c8\u6709\u4e24\u79cd\u65b9\u5f0f\uff0c\u4e00\u79cd\u4e3b\u52a8active mode\uff0c\u4e00\u79cd\u88ab\u52a8passive mode\u3002\u4e3b\u52a8\u6a21\u5f0f\u4e0b\uff0cclient\u4f7f\u7528port\u547d\u4ee4\u544a\u8bc9server\u6211\u7528\u54ea\u4e00\u4e2a\u7aef\u53e3\u63a5\u53d7\u6570\u636e\uff0c\u7136\u540eserver\u4e3b\u52a8\u53d1\u8d77\u5bf9\u8fd9\u4e2a\u7aef\u53e3\u7684\u8bf7\u6c42\u3002\u88ab\u52a8\u6a21\u5f0f\u4e0b\uff0cserver\u4f7f\u7528port\u547d\u4ee4\u544a\u8bc9\u5ba2\u6237\u7aef\uff0c\u5b83\u7528\u90a3\u4e2a\u7aef\u53e3\u76d1\u542c\uff0c\u7136\u540e\u5ba2\u6237\u7aef\u53d1\u8d77\u5bf9\u4ed6\u7684\u6570\u636e\u4f20\u8f93\uff0c\u6240\u4ee5\u8fd9\u5bf9\u4e8e\u4e00\u4e2a\u9632\u706b\u5899\u6765\u8bf4\u5c31\u662f\u6bd4\u8f83\u9ebb\u70e6\u7684\u4e8b\u60c5\uff0c\u56e0\u4e3a\u6709\u53ef\u80fd\u4f1a\u6709new\u72b6\u6001\u7684\u6570\u636e\u5305\uff0c\u4f46\u662f\u5b83\u53c8\u662f\u5408\u7406\u7684\u8bf7\u6c42\uff0c\u8fd9\u4e2a\u65f6\u5019\u5c31\u7528\u5230\u8fd9\u4e2arelated\u72b6\u6001\u4e86\uff0c\u4ed6\u5c31\u662f\u4e00\u79cd\u5173\u8054\uff0c\u5728linux\u4e2d\uff0c\u6709\u4e2a\u53eb ftp_conntrack\u7684\u6a21\u5757\uff0c\u5b83\u80fd\u8bc6\u522bport\u547d\u4ee4\uff0c\u7136\u540e\u5bf9\u76f8\u5e94\u7684\u7aef\u53e3\u8fdb\u884c\u653e\u884c\u3002<\/p>\n<p>\u4e00\u53e3\u6c14\u5199\u4e86\u8fd9\u4e48\u591a\u4e1c\u897f\uff0c\u4e0d\u77e5\u9053\u8d28\u91cf\u5982\u4f55\uff0c\u5927\u5bb6\u51d1\u548c\u7740\u770b\u5427\uff0c\u5e0c\u671b\u591a\u591a\u4ea4\u6d41\u5171\u540c\u8fdb\u6b65\uff0c\u6211\u8fd8\u662f\u4e00\u4e2alinux\u7684\u521d\u5b66\u8005\uff0c\u96be\u514d\u5f88\u591a\u8c2c\u8bef\uff0c\u5e0c\u671b\u9ad8\u624b\u8d50\u6559\u6307\u6b63\uff0c\u4ee5\u671f\u4e0d\u65ad\u8fdb\u6b65\u3002<\/p>\n<h2 id=\"toc_0.6\">\u5b9e\u7528\u547d\u4ee4<\/h2>\n<p>\u5bf9\u4e86\uff0c\u8fd8\u6709\u51e0\u4e2a\u5728\u5b9e\u9645\u4e2d\u6bd4\u8f83\u5b9e\u7528\uff08\u4e5f\u6bd4\u8f83\u53d7\u7528:-)\uff09\u7684\u547d\u4ee4\u53c2\u6570\uff0c\u5199\u51fa\u6765\u4f9b\u5927\u5bb6\u53c2\u8003<\/p>\n<ul>\n<li><code>iptables -L -n<\/code><\/li>\n<\/ul>\n<p>\u8fd9\u6837\u7684\u5217\u8868\u4f1a\u8df3\u8fc7linux\u7684domain lookup,\u6709\u7684\u65f6\u5019\u4f7f\u7528iptables -L\u4f1a\u6bd4\u8f83\u6162\uff0c\u56e0\u4e3alinux\u4f1a\u5c1d\u8bd5\u89e3\u6790ip\u7684\u57df\u540d\uff0c\u771f\u662f\u7f57\u55e6\uff0c\u5982\u679c\u4f60\u7684dns server\u6bd4\u8f83\u4e0d\u723d\u7684\u8bdd\uff0ciptables -L\u5c31\u4f1a\u8ba9\u4f60\u5f88\u4e0d\u723d\uff0c\u52a0\u4e00\u4e2a-n\u53c2\u6570\u5c31\u597d\u4e86\u3002\u5217\u8868\u5237\u7684\u5c31\u51fa\u6765\u3002\u5f53\u7136\u4e86\uff0c\u5982\u679c\u4f60\u7684linux\u5c31\u662f\u505a\u9632\u706b\u5899\uff0c\u5efa\u8bae\u628anameserver\u53bb\u6389\uff0c\u5728 \/etc\/resolve.conf\u91cc\u9762\uff0c\u56e0\u4e3a\u6709\u65f6\u5019\u4f7f\u7528route\u547d\u4ee4\u4e5f\u4f1a\u6bd4\u8f83\u6162\u5217\u51fa\u6765\uff0c\u5f88\u662f\u4e0d\u723d\u3002<\/p>\n<ul>\n<li><code>iptables -L -v<\/code><\/li>\n<\/ul>\n<p>\u8fd9\u4e2a\u547d\u4ee4\u4f1a\u663e\u793a\u94fe\u4e2d\u89c4\u5219\u7684\u5305\u548c\u6d41\u91cf\u8ba1\u6570\uff0c\u563f\u563f\uff0c\u770b\u770b\u54ea\u4e9b\u5c0f\u5b50\u7528\u7684\u6d41\u91cf\u90a3\u4e48\u591a\uff0c\u7528tc\u9650\u4e86\u4ed6\u3002<\/p>\n<ul>\n<li><code>iptables -t nat -L -vn<\/code><\/li>\n<\/ul>\n<p>\u67e5\u770bnat\u8868\u4e2d\u7684\u89c4\u5219\u3002<\/p>\n<ul>\n<li><code>cat \/proc\/net\/ip_conntrack<\/code><\/li>\n<\/ul>\n<p>\u67e5\u770b\u76ee\u524d\u7684conntrack\uff0c\u53ef\u80fd\u4f1a\u6bd4\u8f83\u591a\u54e6\uff0c\u6700\u597d\u52a0\u4e00\u4e2a|grep &#8220;\u5173\u952e\u5b57&#8221;\uff0c\u770b\u770b\u4f60\u611f\u5174\u8da3\u7684\u94fe\u63a5\u8ddf\u8e2a<\/p>\n<ul>\n<li><code>wc -l \/proc\/net\/ip_conntrack<\/code><\/li>\n<\/ul>\n<p>\u770b\u770b\u603b\u94fe\u63a5\u6709\u591a\u5c11\u6761\u3002<\/p>\n<ul>\n<li><code>iptables-save &gt;\/etc\/iptables<\/code><\/li>\n<\/ul>\n<p>\u628a\u5f53\u524d\u7684\u6240\u6709\u94fe\u5907\u4efd\u4e00\u4e0b\uff0c\u4e4b\u6240\u4ee5\u653e\u5230\/etc\u4e0b\u9762\u53ebiptables\uff0c\u56e0\u4e3a\u8fd9\u6837\u91cd\u8d77\u673a\u5668\u7684\u65f6\u5019\u4f1a\u81ea\u52a8\u52a0\u8f7d\u6240\u6709\u7684\u94fe\uff0c\u7ecf\u5e38\u5730\u5907\u4efd\u4e00\u4e0b\u5427\uff0c\u5426\u5219\u5982\u679c\u94fe\u591a\uff0c\u4e07\u4e00\u6389\u7535\u91cd\u542f\uff0c\u4f60\u8fd8\u662f\u4f1a\u6bd4\u8f83\u75db\u82e6\u3002<\/p>\n<ul>\n<li>\u8f6c\u53d1<\/li>\n<\/ul>\n<p>\u4e4b\u524d\u56e0\u4e3a\u4e00\u4e2a\u7f51\u6bb5\u88ab\u5c01\u4e86\uff0c\u56e0\u6b64\u901a\u8fc7iptables\u505a\u8f6c\u53d1\uff1a<\/p>\n<p>\u4ee3\u7406\u670d\u52a1\u5668WAN IP\uff1a<code>111.**.**.219<\/code>\uff0cLAN IP\uff1a192.168.0.219<\/p>\n<p>\u5185\u7f51\u670d\u52a1\u5668IP\uff1a192.168.0.41<\/p>\n<p>1.\u5728\u4ee3\u7406\u670d\u52a1\u5668\u6253\u5f00\u8f6c\u53d1\u529f\u80fd\uff08sysctl.conf\uff09<\/p>\n<p>2.\u6dfb\u52a0\u4ee5\u4e0b\u89c4\u5219<\/p>\n<pre>iptables -t nat -A PREROUTING -d 111.**.**.219 -p tcp --dport 9999 -j DNAT --to-destination 192.168.0.41:9999\r\niptables -t nat -A POSTROUTING -d 192.168.0.41 -p tcp --dport 9999 -j SNAT --to-source 192.168.0.219\r\n\r\n\r\n<\/pre>\n<p>\u8a2d\u5b9a\u4fdd\u5b58<\/p>\n<p>&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;-oooooooooooK&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;-<\/p>\n<h4>\/etc\/network\/if-pre-up.d\/iptables<\/h4>\n<pre>#!\/bin\/sh\r\niptables-restore &lt; \/etc\/iptables\/rules.v4\r\nexit 0\r\n\r\nhttps:\/\/qiita.com\/amedama\/items\/d191ae7d158f5bd016c9<\/pre>\n<p>&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;-<\/p>\n<p><iframe class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" title=\"Raspberry Pi \u3068 iptables - Origami Devices\" src=\"https:\/\/hatenablog-parts.com\/embed?url=http%3A%2F%2Fktgohan.hatenablog.com%2Fentry%2F2014%2F12%2F21%2F213931#?secret=cMskC7MYuO\" data-secret=\"cMskC7MYuO\" scrolling=\"no\" frameborder=\"0\"><\/iframe><\/p>\n<pre class=\"code\" data-lang=\"\" data-unlink=\"\">sudo aptitude install iptables-persistent<\/pre>\n<pre class=\"code\" data-lang=\"\" data-unlink=\"\">sudo \/etc\/init.d\/iptables-persistent restart<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>http:\/\/xstarcd.github.io\/wiki\/Linux\/iptables_forward_in [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[27],"tags":[],"_links":{"self":[{"href":"https:\/\/vongg.com\/index.php?rest_route=\/wp\/v2\/posts\/811"}],"collection":[{"href":"https:\/\/vongg.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vongg.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vongg.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/vongg.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=811"}],"version-history":[{"count":6,"href":"https:\/\/vongg.com\/index.php?rest_route=\/wp\/v2\/posts\/811\/revisions"}],"predecessor-version":[{"id":820,"href":"https:\/\/vongg.com\/index.php?rest_route=\/wp\/v2\/posts\/811\/revisions\/820"}],"wp:attachment":[{"href":"https:\/\/vongg.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=811"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vongg.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=811"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vongg.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=811"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}