{"id":254469,"date":"2013-12-31T22:38:53","date_gmt":"2013-12-31T14:38:53","guid":{"rendered":"http:\/\/blog.zhenglei.net\/?p=254469"},"modified":"2013-12-31T22:38:53","modified_gmt":"2013-12-31T14:38:53","slug":"%e8%bd%ac%ef%bc%9amiddleboxes","status":"publish","type":"post","link":"https:\/\/blog.zhenglei.net\/?p=254469","title":{"rendered":"\u8f6c\uff1amiddleboxes"},"content":{"rendered":"

http:\/\/www.cnblogs.com\/epan\/articles\/98944.html<\/p>\n

<\/a><\/p>\n

\u901a\u8fc7middlebox\u5b9e\u65bdP2P\u901a\u8baf<\/a><\/h1>\n

[\u6587\u7ae0\u4fe1\u606f]<\/span>
\n\u4f5c\u8005blog:\u00a0\u00a0 http:\/\/www.blogcn.com\/User6\/caimouse\/index.html<\/a>
\n<\/span>\u4f5c\u8005\u7684\u8bdd:\u00a0 \u6211\u662f\u4e00\u8fb9\u770b\u4e00\u8fb9\u968f\u624b\u7ffb\u7684\uff0c\u7ffb\u7684\u5f88\u5dee\uff0c\u672c\u6765\u4e0d\u597d\u610f\u601d\u8d34\u51fa\u6765\u7684\uff0c\u53ef\u80fd\u5927\u5bb6\u770b\u539f\u6587\u66f4\u660e\u767d\u4e9b\u3002\u5e0c\u671b\u5bf9\u5927\u5bb6\u6709\u4e00\u4e9b\u5e2e\u52a9\uff0c\u6211\u7684\u76ee\u7684\u662f\u5e0c\u671b\u80fd\u548c\u6709\u5174\u8da3\u548c\u6b63\u5728\u505aP2P\u7684\u7a0b\u5e8f\u5458\u4eec\u7ed3\u4ea4\u670b\u53cb\uff0c\u8c22\u8c22\u5927\u5bb6\u652f\u6301\u3002
\n\u4f5c\u8005\u7684MSN\uff1ablovearcher@hotmail.com<\/a>
\n\u4f5c\u8005\u7684\u00a0QQ: 27443675<\/p>\n

epan\u63d0\u793a:\u4e0b\u9762\u6709\u4e9b\u56fe\u770b\u4e0d\u6e05\u695a\u7684\u53ef\u4ee5copy\u5230\u8bb0\u4e8b\u672c\u770b,\u8bb0\u4e8b\u672c\u4e0d\u8981\u81ea\u52a8\u6362\u884c.<\/span><\/p>\n

1. \u4ecb\u7ecd
\n\u4eca \u5929\u7684Internet\u7684”middleboxes”\u5df2\u7ecf\u666e\u904d\u5b58\u5728, \u6bd4\u5982\u8c61\u7f51\u7edc\u5730\u5740\u8f6c\u6362(NAT)\uff0c\u4e3b\u8981\u662f\u56e0\u4e3aIPv4\u7684\u5730\u5740\u7a7a\u95f4\u6d88\u8017\u5371\u673a\u4e2d\u4ea7\u751f\u7684\u4e00\u4e2a\u89e3\u51b3\u65b9\u6848\u3002\u7136\u800c\uff0c\u7531\u8fd9\u4e9b”middleboxes”\u5efa\u7acb\u7684\u4e0d\u5bf9\u79f0\u5bfb\u5740\u548c \u8fde\u63a5\uff0c\u5df2\u7ecf\u6210\u4e3a\u70b9\u5bf9\u70b9 (P2P)\u5e94\u7528\u548c\u534f\u8bae\u4e2d\u72ec\u7279\u7684\u95ee\u9898, \u8fd9\u4e9b\u5e94\u7528\u548c\u534f\u8bae\u5305\u62ec\u4f8b\u5982\u7f51\u7edc\u7535\u8bdd\u548c\u591a\u4eba\u5728\u7ebf\u6e38\u620f\u3002\u8fd9\u4e9b\u8bdd\u9898\u751a\u81f3\u53ef\u80fd\u5728\u4f7f\u7528 IPv6 \u534f\u8bae\u540e\u7ee7\u7eed\u5b58\u5728, \u6bd4\u5982\u8bf4\u5728 NAT \u5e38\u88ab\u5f53\u4f5c\u517c\u5bb9 IPv4 \u673a\u5236[NAT-PT]\u7684\u5730\u65b9\uff0c\u8fd8\u6709\u5f53NAT \u4e0d\u518d\u9700\u8981\u4e4b\u540e\uff0c\u9632\u706b\u5899\u5c06\u4f1a\u4f9d\u7136\u5b58\u5728(\u8fd9\u4e9b\u95ee\u9898)\u3002<\/p>\n

\u5f53\u524d\u53d1\u5c55\u7684”middleboxes”\u6700\u521d\u8ba1\u5212\u7528\u5728C\/S\u7ed3\u6784\u4e2d\uff0c\u5373\u5728\u90a3\u4e9b\u76f8\u5173\u7684\u533f\u540d\u5ba2\u6237\u7aef\u4e3b\u52a8\u53bb\u8fde\u63a5\u6709\u7740\u56fa\u5b9aIP\u5730\u5740\u548cDNS\u57df\u540d\u7684\u53ef\u8fde\u63a5\u4e3b \u673a\u3002\u5927\u591a\u6570\u7684”middleboxes”\u5b9e\u73b0\u4e00\u4e2a\u4e0d\u5bf9\u79f0\u7684\u6c9f\u901a\u6a21\u578b\uff0c\u5373\u90a3\u4e9b\u79c1\u6709\u7684\u5185\u90e8\u7f51\u7edc\u4e0a\u7684\u4e3b\u673a\u53ef\u4ee5\u548c\u516c\u7f51\u4e0a\u7684\u4e3b\u673a\u8fde\u63a5\u901a\u8baf\uff0c\u4f46\u662f\u516c\u7f51\u4e0a\u7684\u5916\u90e8\u4e3b\u673a\u4e0d\u80fd \u591f\u548c\u5185\u7f51\u4e0a\u7684\u4e3b\u673a\u901a\u8baf\u9664\u4e86\u88ab middlebox”s \u7684\u7ba1\u7406\u8005\u660e\u786e\u5730\u914d\u7f6e\u4e4b\u5916\u3002 \u5728 NAPT \u7684\u901a\u5e38\u60c5\u5f62\u4e2d\uff0c\u5728\u5185\u90e8\u7f51\u7edc\u4e0a\u7684\u4e00\u4f4d\u5ba2\u6237\u673a\u5728\u516c\u7f51\u4e0a\u5e76\u6ca1\u6709\u4e00\u4e2a\u552f\u4e00\u72ec\u7279\u7684IP\u5730\u5740\uff0c\u4f46\u662f\u53ef\u4ee5\u5728\u540c\u4e00\u79c1\u7f51\u4e0a\u7684\u5176\u4ed6\u5ba2\u6237\u673a\u4e00\u6837\uff0c\u5206\u4eab\u4e00\u4e2a\u516c\u7f51IP\u5730\u5740\uff0c\u5e76\u6709 NAPT\u7ba1\u7406\u3002 \u8fd9\u4e9b\u5728\u4e00\u53f0”middlebox”\u540e\u7684\u4e0d\u77e5\u9053\u540d\u79f0\u548c\u4e0d\u6613\u8bbf\u95ee\u7684\u5185\u90e8\u4e3b\u673a\u5bf9\u5ba2\u6237\u7aef\u8f6f\u4ef6\u6bd4\u5982\u7f51\u9875\u6d4f\u89c8\u5668\u5e76\u4e0d\u662f\u4e00\u4e2a\u95ee\u9898\uff0c\u5b83\u4eec\u4e4b\u9700\u8981\u5411\u5916\u8fde\u63a5\u3002\u800c\u4e14\u8fd9\u79cd\u4e0d\u6613\u8bbf\u95ee \u7684\u7279\u6027\u6709\u65f6\u5019\u88ab\u89c6\u4e3a\u5bf9\u4fdd\u62a4\u9690\u79c1\u6709\u5229\u3002<\/p>\n

\u4f46\u662f\uff0c\u5728\u70b9\u5bf9\u70b9\u7684\u5e94\u7528\u4e2d\uff0c\u82f1\u7279\u7f51\u4e0a\u7684\u4e3b\u673a\u901a\u5e38\u4f1a\u8003\u8651\u8981\u548c”\u5ba2\u6237”\u5efa\u7acb\u76f4\u63a5\u548c\u5f7c\u6b64\u8bbf\u95ee\u7684\u901a\u8bdd\u8fde\u63a5\u3002\u547c\u53eb\u8005\u548c\u88ab\u53eb\u8005\u53ef\u80fd\u4f1a\u5728\u4e0d\u540c \u7684”middleboxes” \u540e\u9762\uff0c\u4e24\u8005\u90fd\u53ef\u80fd\u6ca1\u6709\u4efb\u4f55\u7684\u56fa\u5b9aIP\u5730\u5740\u6216\u8005\u5176\u4ed6\u7684\u516c\u7f51\u5b58\u5728\u8868\u73b0\u3002\u4e3e\u4f8b\u6765\u8bf4\uff0c\u4e00\u4e2a\u901a\u5e38\u7684\u5728\u7ebf\u6e38\u620f\u67b6\u6784\uff0c\u662f\u8ba9\u53c2\u52a0\u6e38\u620f\u7684\u4e3b\u4eba\u8fde\u63a5\u5230\u4e00\u4e2a\u5927\u5bb6\u90fd\u77e5\u9053\u7684\u670d\u52a1\u5668\u4e0a \u8bbe\u5b9a\u4e00\u4e9b\u521d\u8bc6\u503c\uff0c\u4ee5\u53ca\u8fde\u63a5\u540e\u7684\u4f7f\u7528\u76ee\u7684\u3002\u7136\u540e\uff0c\u4e3a\u4e86\u5728\u6e38\u620f\u671f\u95f4\u6709\u66f4\u52a0\u5feb\u901f\u548c\u6709\u6548\u7684\u6e38\u620f\u901f\u5ea6\uff0c\u9700\u8981\u5efa\u7acb\u5f7c\u6b64\u76f4\u63a5\u7684\u8fde\u63a5\u3002\u540c\u6837\u5730\uff0c\u4e00\u4e2a\u53ef\u5171\u4eab\u7684\u6587\u4ef6\u53ef\u80fd\u53ef\u4ee5\u8ba9 \u4e00\u4e2a\u5927\u5bb6\u90fd\u77e5\u9053\u7684\u8d44\u6e90\u641c\u7d22\u5f15\u64ce\u53d1\u73b0\u6216\u8005\u67e5\u627e\u5230\uff0c\u4f46\u5982\u679c\u9700\u8981\u6587\u4ef6\u6570\u636e\u4f20\u8f93\uff0c\u5c31\u9700\u8981\u548c\u90a3\u53f0\u5171\u4eab\u6587\u4ef6\u7684\u4e3b\u673a\u5efa\u7acb\u76f4\u63a5\u7684\u8fde\u63a5\u4e86\u3002\u5728\u70b9\u5bf9\u70b9\u8fde\u63a5 \u65f6\uff0c”middlebox”\u5c31\u751f\u6210\u4e86\u4e00\u4e2a\u95ee\u9898\u3002\u56e0\u4e3a\u5728”middlebox”\u540e\u9762\u7684\u90a3\u4e9b\u9700\u8981\u7528TCP\u6216\u8005UDP\u548c\u5176\u4ed6\u673a\u5668\u8fde\u63a5\u7684\u4e3b\u673a\u901a\u5e38\u6ca1\u6709\u56fa\u5b9a\u53ef\u7528\u7684\u516c \u7f51\u7aef\u53e3\u53ef\u4ee5\u8fdb\u884c\u8fde\u63a5\u3002 RFC 3235[ NAT-APPL]\u7b80\u77ed\u5730\u8bf4\u660e\u4e86\u8fd9\u4e2a\u95ee\u9898\uff0c\u4f46\u662f\u6ca1\u6709\u63d0\u4f9b\u4efb\u4f55\u7684\u901a\u5e38\u89e3\u51b3\u65b9\u6848\u3002<\/p>\n

\u5728\u8fd9\u4e00\u4efd\u6587\u6863\u4e2d\uff0c\u6211\u4eec\u5c31 P2P\/ middlebox \u95ee\u9898\u67092\u70b9\u8bf4\u660e\u3002 \u9996\u5148\uff0c\u6211\u4eec\u603b\u7ed3\u90a3\u4e9b\u5728middleboxes\u5b58\u5728\u65f6P2P\u5e94\u7528\u7a0b\u5e8f\u53ef\u4ee5\u5de5\u4f5c\u7684\u5df2\u77e5\u65b9\u6cd5\u3002\u5176\u6b21\uff0c\u6211\u4eec\u63d0\u4f9b\u57fa\u4e8e\u8fd9\u4e9b\u5b9e\u8df5\u7684\u4e00\u5957\u5e94\u7528\u7a0b\u5e8f\u8bbe\u8ba1\u6307\u5bfc\u65b9\u9488\u4f7fP2P\u5728 middleboxes\u4e0b\u5e94\u7528\u7684\u66f4\u5065\u5eb7\u3002\u66f4\u8fdb\u4e00\u6b65\uff0c\u6211\u4eec\u63d0\u4f9b\u7684\u8bbe\u8ba1\u6307\u5bfc\u65b9\u9488\u53ef\u4ee5\u8ba9\u5c06\u6765\u7684 middleboxes \u66f4\u6709\u6548\u7387\u7684\u652f\u6301\u652f\u63f4 P2P \u5e94\u7528\u3002 \u6211\u4eec\u7684\u91cd\u70b9\u662f\u8981\u80fd\u591f\u7a7f\u900f middleboxes\uff0c\u4ee5\u63d0\u4f9b\u66f4\u5e7f\u9614\u548c\u66f4\u76f4\u63a5\u7684P2P \u5e94\u7528\u3002<\/p>\n

2. \u672f\u8bed
\n\u5728\u672c\u7ae0\u4e2d\u6211\u4eec\u9996\u5148\u7b80\u8981\u63cf\u8ff0\u4e00\u4e0b\u4e00\u4e9b”middlebox”\u672f\u8bed\uff0c\u6211\u4eec\u8fd9\u91cc\u7684\u91cd\u70b9\u662f\u4e24\u79cd\u5e38\u5bfc\u81f4P2P\u5e94\u7528\u51fa\u73b0\u95ee\u9898\u7684middlebox.<\/p>\n

\u9632\u706b\u5899
\n\u4e00\u4e2a\u9632\u706b\u5899\u9650\u5236\u79c1\u4eba\u5185\u7f51\u548c\u516c\u4f17\u82f1\u7279\u7f51\u4e4b\u95f4\u7684\u901a\u8baf\uff0c\u5178\u578b\u5730\u9632\u706b\u5899\u5c31\u662f\u4e22\u5f03\u90a3\u4e9b\u5b83\u8ba4\u4e3a\u672a\u7ecf\u8bb8\u53ef\u7684\u6570\u636e\u5305\u3002\u5728\u6570\u636e\u5305\u7a7f\u8d8a\u4e00\u4e2a\u9632\u706b\u5899\u65f6\uff0c\u5b83\u68c0\u67e5\u4f46\u662f\u4e0d\u4fee\u6539\u5305\u91cc\u7684 IP\u5730\u5740\u548cTCP\/ UDP \u7aef\u53e3\u4fe1\u606f\u3002<\/p>\n

\u7f51\u7edc\u5730\u5740\u8f6c\u6362(NAT)
\n\u5f53\u6570\u636e\u5305\u7a7f\u8fc7NAT\u65f6\uff0cNAT\u4e0d\u4ec5\u68c0\u67e5\u540c\u65f6\u4e5f\u4fee\u6539\u6570\u636e\u7684\u5305\u5934\u4fe1\u606f\uff0c\u5e76\u4e14\u5141\u8bb8\u66f4\u591a\u7684\u5728NAT\u540e\u7684\u4e3b\u673a\u5206\u4eab\u5c11\u6570\u516c\u7f51IP\u5730\u5740(\u901a\u5e38\u53ea\u67091\u4e2a)\u3002<\/p>\n

NAT\u901a\u5e38\u67092\u79cd\u4e3b\u8981\u7c7b\u578b\uff1a
\nBasic Nat
\n\u4e00\u4e2aBasic NAT\u6620\u5c04\u4e00\u4e2a\u5185\u5728\u7684\u79c1\u6709IP\u5730\u5740\u5230\u4e00\u4e2a\u516c\u7f51IP\u5730\u5740\uff0c\u4f46\u5f53\u6570\u636e\u5305\u7a7f\u8fc7NAT\u65f6\uff0c\u4e0d\u66f4\u6362\u5b83\u7684TCP\/UDP\u7aef\u53e3\u53f7\u3002Basic Nat\u901a\u5e38\u662f\u53ea\u7528\u5728\u4e00\u4e9b\u5177\u5907\u516c\u5171IP\u5730\u5740\u6c60\u7684NAT\u4e0a\uff0c\u901a\u8fc7\u5b83\u53ef\u4ee5\u5730\u5740\u7ed1\u5b9a\uff0c\u5373\u4ee3\u8868\u4e00\u53f0\u5185\u90e8\u4e3b\u673a\u3002<\/p>\n

Network Address\/Port Translator (NAPT)
\n\u4f46\u662f\u6700\u901a\u5e38\u7684\uff0c\u5f53\u6570\u636e\u5305\u7a7f\u8fc7NAT\u65f6\uff0c\u4e00\u4e2aNAPT\u68c0\u67e5\u5e76\u4fee\u6539\u5b83\u7684TCP\/UDP\u7aef\u53e3\uff0c\u90a3\u4e48\u5c31\u53ef\u4ee5\u5141\u8bb8\u591a\u53f0\u5185\u7f51\u4e3b\u673a\u540c\u65f6\u5171\u4eab\u4e00\u4e2a\u5355\u72ec\u7684\u516c\u7f51IP\u5730\u5740\u4e86\u3002<\/p>\n

\u5173\u4e8e NAT \u7684\u5206\u7c7b\u548c\u672f\u8bed\uff0c[NAT-TRAD] \u548c [NAT-TERM]\u4e2d\u6709\u66f4\u591a\u7684\u4fe1\u606f\u3002\u90a3\u4e9b\u5c06\u6765\u5206\u7c7b\u7684NAPT\u7684\u9644\u52a0\u672f\u8bed\u5728\u8f83\u8fd1\u7684\u5de5\u4f5c[STUN]\u4e2d\u88ab\u5b9a\u4e49\u3002\u5f53\u4e00\u4e2a\u5185\u7f51\u7684\u4e3b\u673a\u7ecf\u8fc7\u4e00\u4e2aNAT\u548c\u5916\u90e8\u8fdb\u884c TCP\u6216\u8005UDP\u8fde\u63a5\u7684\u671f\u95f4\uff0cNAPT\u5206\u914d\u4e00\u4e2a\u516c\u7f51IP \u4f4f\u5740\u548c\u7aef\u53e3\uff0c\u4ee5\u4fbf\u6765\u81ea\u5916\u90e8\u7ec8\u7aef\u54cd\u5e94\u7684\u6570\u636e\u5305\u80fd\u88abNAPT\u63a5\u6536\uff0c\u89e3\u91ca\uff0c\u5e76\u8f6c\u53d1\u7ed9\u5185\u7f51\u7684\u4e3b\u673a\u3002\u8fd9\u4e2a\u7ed3\u679c\u662f\u7531 NAPT \u5efa\u7acb\u4e00\u4e2a(\u79c1\u6709IP\u5730\u5740\uff0c\u79c1\u6709\u7aef\u53e3)\u548c(\u516c\u7f51IP\u5730\u5740\uff0c\u516c\u7f51\u7aef\u53e3)\u4e4b\u95f4\u7684\u7aef\u53e3\u7ed1\u5b9a\u5b9e\u73b0\u7684\u3002\u5728\u8fd9\u4e2a\u671f\u95f4NAPT\u5c06\u4e3a\u7ed1\u5b9a\u7684\u7aef\u53e3\u6267\u884c\u5730\u5740\u7ffb\u8bd1\u3002\u4e00\u4e2a\u5173\u4e8eP2P \u5e94\u7528\u7684\u95ee\u9898\u662f\uff0c\u5f53\u4e00\u4e2a\u5185\u90e8\u4e3b\u673a\u4ece\u4e00\u4e2a\u79c1\u6709IP\uff0c\u79c1\u6709\u7aef\u53e3\u540c\u65f6\u4e0e\u5916\u7f51\u4e0a\u7684\u591a\u53f0\u4e0d\u540c\u7684\u4e3b\u673a\u5efa\u7acb\u591a\u4e2a\u8fde\u63a5\u65f6\uff0cNAT\u662f\u5982\u4f55\u8fd0\u4f5c\u7684\u3002<\/p>\n

Cone NAT
\n\u5efa\u7acb\u4e00\u4e2a\u7aef\u53e3\uff0c\u628a\u4e00\u4e2a(\u79c1\u6709IP\uff0c\u79c1\u6709\u7aef\u53e3)\u548c(\u516c\u7528IP\uff0c\u516c\u7528\u7aef\u53e3)\u7ed1\u5b9a\u540e\uff0c\u5bf9\u4e8e\u4ee5\u540e\u6765\u81ea\u540c\u4e00\u79c1\u6709IP\u548c\u7aef\u53e3\u53f7\u7684\u5e94\u7528\u8fde\u63a5\uff0ccone NAT\u5c06\u91cd\u590d\u4f7f\u7528\u8fd9\u4e2a\u7ed1\u5b9a\u7684\u7aef\u53e3\uff0c\u53ea\u8981\u6709\u4e00\u4e2a\u8fde\u63a5\u4f1a\u8bdd\uff0c\u8fd9\u4e2a\u7ed1\u5b9a\u7aef\u53e3\u5c31\u4f1a\u4fdd\u6301\u6fc0\u6d3b\u72b6\u6001\u3002
\n\u4f8b \u5982\uff0c\u4e0b\u9762\u56fe\u8868\u4e2d\uff0c\u63a8\u60f3\u4e00\u4e0b\u5ba2\u6237\u7aefA\u901a\u8fc7\u4e00\u4e2acone NAT\u540c\u65f6\u5efa\u7acb2\u4e2a\u5916\u90e8\u4f1a\u8bdd\uff0c\u4ece\u540c\u6837\u7684\u5185\u90e8\u7f51\u7edc\u7ec8\u7aef(10.0.0.1:1234)\u52302\u4e2a\u4e0d\u540c\u7684\u5916\u90e8\u670d\u52a1\u5668\uff0cS1\u548cS2\u3002cone NAT\u53ea\u4f1a\u5206\u914d\u4e00\u4e2a\u516c\u7528\u7684\u7ec8\u7aef\uff0c155.99.25.11:62000\uff0c\u90fd\u4f1a\u5230\u4e24\u4e2a\u4f1a\u8bdd\uff0c\u5e76\u5728\u5730\u5740\u8f6c\u6362\u671f\u95f4\u786e\u4fdd\u5ba2\u6237\u7aef\u7aef\u53e3\u7684\u4e00\u81f4\u3002Basic NAT\u548c\u9632\u706b\u5899\u4e0d\u4fee\u6539\u901a\u8fc7middlebox\u7684\u6570\u636e\u5305\u4e2d\u7684\u7aef\u53e3\u53f7\uff0c\u8fd9\u4e9b\u7c7b\u578b\u7684middlebox\u53ef\u4ee5\u88ab\u8ba4\u4e3a\u662f\u4e00\u79cd\u7279\u6b8a\u7684Cone Nat\u3002<\/p>\n

Server S1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Server S2
\n18.181.0.31:1235\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 138.76.29.7:1235
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n+———————-+———————-+
\n|
\n^\u00a0 Session 1 (A-S1)\u00a0 ^\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 ^\u00a0 Session 2 (A-S2)\u00a0 ^
\n|\u00a0 18.181.0.31:1235\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0 138.76.29.7:1235\u00a0 |
\nv 155.99.25.11:62000 v\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 v 155.99.25.11:62000 v
\n|
\nCone NAT
\n155.99.25.11
\n|
\n^\u00a0 Session 1 (A-S1)\u00a0 ^\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 ^\u00a0 Session 2 (A-S2)\u00a0 ^
\n|\u00a0 18.181.0.31:1235\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0 138.76.29.7:1235\u00a0 |
\nv\u00a0\u00a0 10.0.0.1:1234\u00a0\u00a0\u00a0 v\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 v\u00a0\u00a0 10.0.0.1:1234\u00a0\u00a0\u00a0 v
\n|
\nClient A
\n10.0.0.1:1234<\/p>\n

Symmetric NAT
\n\u5bf9\u79f0\u7684NAT(Symmetric NAT)\uff0c\u4e0eCone NAT\u6709\u660e\u663e\u5dee\u522b\uff0c\u5728\u6240\u6709\u4f1a\u8bdd\u671f\u95f4\u4e2d\u4e0d\u4f1a\u4fdd\u6301\u7ed1\u5b9a(\u79c1\u6709IP\uff0c\u79c1\u6709\u7aef\u53e3)\u548c(\u516c\u5171IP\uff0c\u516c\u5171\u7aef\u53e3)\u7684\u7aef\u53e3\u4e0d\u53d8\u3002\u76f8\u53cd\uff0c\u5b83\u4f1a\u4e3a\u6bcf\u4e2a\u65b0\u5bf9\u8bdd\u91cd\u65b0\u5206\u914d\u4e00\u4e2a\u65b0\u7684\u516c\u5171\u7aef\u53e3\u3002
\n\u4e3e \u4f8b\u6765\u8bf4\uff0c\u8bbe\u60f3\u5ba2\u6237A\u4ece\u540c\u6837\u7aef\u53e3\u4e0a\u8981\u53d1\u8d77\u4e24\u4e2a\u5916\u90e8\u5bf9\u8bdd\uff0c\u4e00\u4e2a\u548cS1\u8fde\u63a5\uff0c\u53e6\u4e00\u4e2a\u548cS2\u8fde\u63a5\u3002Symmetric NAT\u53ef\u80fd\u4f1a\u4e3a\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\u5206\u914d\u4e00\u4e2a\u516c\u5171\u7684\u7aef\u70b9 155.99.25.11:62000\uff0c\u800c\u4e3a\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\u5206\u914d\u4e00\u4e2a\u4e0d\u540c\u7684\u516c\u5171\u7aef\u70b9155.99.25.11:62001\u3002\u4e3a\u4e86\u5730\u5740\u8f6c\u6362\uff0cNAT\u53ef\u4ee5\u533a\u5206\u8fd9\u4e24 \u4e2a\u4f1a\u8bdd\u4f20\u8f93\u7684\u76ee\u7684\uff0c\u56e0\u4e3a\u548c\u8fd9\u4e9b\u4f1a\u8bdd\u6709\u5173\u7684\u5916\u90e8\u7aef\u70b9(\u5c31\u662fS1\u3001S2)\u662f\u4e0d\u540c\u7684\uff0c\u751a\u81f3\u5728\u901a\u8fc7\u5730\u5740\u8f6c\u6362\u65f6\u4e22\u5931\u4e86\u5ba2\u6237\u7aef\u7684\u76ee\u7684\u6807\u793a\u3002(\u5373\u4e22\u4e86S1\u3001S2\u7684IP\u5730 \u5740NAT\u4e5f\u77e5\u9053\u5982\u4f55\u533a\u5206\uff0c\u6211\u662f\u8fd9\u4e48\u7406\u89e3\u7684\uff0c\u53ef\u80fd\u6709\u8bef\u3002)<\/p>\n

Server S1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Server S2
\n18.181.0.31:1235\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 138.76.29.7:1235
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n+———————-+———————-+
\n|
\n^\u00a0 Session 1 (A-S1)\u00a0 ^\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 ^\u00a0 Session 2 (A-S2)\u00a0 ^
\n|\u00a0 18.181.0.31:1235\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0 138.76.29.7:1235\u00a0 |
\nv 155.99.25.11:62000 v\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 v 155.99.25.11:62001 v
\n|
\nSymmetric NAT
\n155.99.25.11
\n|
\n^\u00a0 Session 1 (A-S1)\u00a0 ^\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 ^\u00a0 Session 2 (A-S2)\u00a0 ^
\n|\u00a0 18.181.0.31:1235\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0 138.76.29.7:1235\u00a0 |
\nv\u00a0\u00a0 10.0.0.1:1234\u00a0\u00a0\u00a0 v\u00a0\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0 v\u00a0\u00a0 10.0.0.1:1234\u00a0\u00a0\u00a0 v
\n|
\nClient A
\n10.0.0.1:1234<\/p>\n

Cone NAT\u548cSymmetric NAT\u4e4b\u95f4\u7684\u6bd4\u8f83\u4e0eTCP\/UDP\u4e4b\u95f4\u7684\u6bd4\u8f83\u6709\u4e9b\u7c7b\u4f3c\u3002(TCP\u9700\u8981\u7ed1\u5b9a\uff0cUDP\u4e0d\u9700\u8981\uff0cCone NAT\u9700\u8981\u7ed1\u5b9a\uff0cSymmetric NAT\u4e0d\u9700\u8981)<\/p>\n

\u6309\u7167NAT\u4ece\u5df2\u77e5\u7684\u516c\u5171IP\uff0c\u516c\u5171\u7aef\u53e3\u63a5\u6536\u7684\u6570\u636e\u9650\u5236\uff0cCone NAT\u53ef\u4ee5\u66f4\u8fdb\u4e00\u6b65\u7684\u8fdb\u884c\u5206\u7c7b\u3002\u8fd9\u79cd\u5206\u7c7b\u901a\u5e38\u90fd\u662fUDP\u8fde\u63a5\u7684\uff0c\u56e0\u4e3aNAT\u548c\u9632\u706b\u5899\u4f1a\u62d2\u7edd\u4efb\u4f55\u65e0\u6761\u4ef6\u7684TCP\u8fde\u63a5\uff0c\u9664\u975e\u660e\u786e\u5730\u4ee5\u522b\u7684\u65b9\u5f0f\u914d\u7f6e\u3002<\/p>\n

Full Cone NAT
\n\u5728\u7ed9\u4e00\u4e2a\u65b0\u7684\u5916\u90e8\u4f1a\u8bdd\u5efa\u7acb\u4e86\u4e00\u4e2a\u516c\u5171\/\u79c1\u6709\u7684\u7aef\u53e3\u7ed1\u5b9a\u540e\uff0c\u4e00\u4e2afull cone NAT\u5c31\u53ef\u4ee5\u901a\u8fc7\u8fd9\u4e2a\u516c\u5171\u7aef\u53e3\u4ece\u516c\u7f51\u4e0a\u7684\u4efb\u4f55\u5916\u90e8\u7aef\u70b9\u63a5\u6536\u6570\u636e\u901a\u8baf\u4e86\u3002Full cone NAT\u4e5f\u5e38\u5e38\u53eb\u505a”\u6df7\u5408”NAT\u3002<\/p>\n

Restricted Cone NAT
\n\u5f53\u7f51\u7edc\u4e3b\u673a\u53d1\u4e00\u4e2a\u6216\u8005\u51e0\u4e2a\u6570\u636e\u5305\u7ed9\u5916\u90e8\u4e3b\u673a\u540e\uff0c\u4e00\u4e2a\u53d7\u9650\u7684cone NAT(Restricted Cone NAT)\u624d\u4f1a\u63a5\u53d7\u6765\u81ea\u8fd9\u4e2a\u5916\u90e8(\u6e90)IP\u5730\u5740\u7684\u6570\u636e\u5305\u3002\u53d7\u9650\u7684cone NAT\u6709\u6548\u7684\u8fd0\u7528\u4e86\u9632\u706b\u5899\u7684\u539f\u7406\uff0c\u62d2\u7edd\u6ca1\u6709\u8981\u6c42\u7684\u6570\u636e\uff0c\u53ea\u63a5\u6536\u5df2\u77e5\u9053\u7684\u5916\u90e8IP\u5730\u5740\u4f20\u6765\u7684\u6570\u636e\u3002(\u504f\u5f00\u539f\u6587\uff0c\u5927\u610f\u5c31\u662f\u7f51\u7edc\u4e3b\u673a\u9700\u8981\u53d1\u4e00\u4e2a\u8bf7\u6c42\u7ed9\u5916\u90e8IP\u5730 \u5740\u8981\u6c42\u8981\u6570\u636e\uff0cNAT\u624d\u4f1a\u63a5\u6536\u8fd9\u4e2a\u5916\u90e8IP\u5730\u5740\u4f20\u6765\u7684\u6570\u636e\uff0c\u4e0d\u7136\u4e0d\u63a5\u6536\u3002)<\/p>\n

Port-Restricted Cone NAT
\n\u4e00\u4e2a\u7aef\u53e3\u53d7\u9650\u7684cone NAT(Port-Restricted Cone NAT)\uff0c\u4e5f\u662f\u8fd9\u6837\uff0c\u53ea\u63a5\u6536\u90a3\u4e9b\u7f51\u7edc\u4e3b\u673a\u66fe\u7ecf\u53d1\u7ed9\u4e00\u4e2a\u5916\u90e8IP\u5730\u5740\u548c\u7aef\u53e3\u76f8\u5339\u914d\u7684\u6570\u636e\u3002\u4e00\u4e2aPort-Restricted cone NAT\u53ef\u4ee5\u548c\u5bf9\u79f0 NAT\u4e00\u6837(symmetric NAT)\uff0c\u4fdd\u62a4\u5185\u90e8\u8282\u70b9\u4e0d\u63a5\u6536\u672a\u88ab\u8bf7\u6c42\u7684\u6570\u636e\u5305\uff0c\u4f46\u662f\u4fdd\u6301\u4e00\u4e2a\u79c1\u6709\u7aef\u53e3\u5728\u8fde\u63a5\u8fc7\u7a0b\u4e2d\u4e0d\u53d8\u3002
\n(\u504f\u5f00\u539f\u6587\uff0c\u5373\u4e0d\u4ec5\u8bf7\u6c42\u7684IP\u548c\u5916\u90e8\u53d1\u6765\u6570\u636e\u7684IP\u662f\u4e00\u6837\u7684\uff0cPORT\u4e5f\u8981\u662f\u4e00\u6837\uff0c\u8fd9\u6837\u624d\u63a5\u6536\u6570\u636e\u3002\u5bf9\u79f0NAT\u4e5f\u6709\u8fd9\u4e2a\u6548\u679c\uff0c\u4f46\u8fd9\u79cdcone NAT\u4fdd\u6301\u7aef\u53e3\u4e0d\u53d8\uff0c\u800c\u5bf9\u79f0NAT\u8981\u53d8\u7aef\u53e3\u53f7\u7684)\u3002<\/p>\n

\u6700\u540e\uff0c\u5728\u8fd9\u7bc7\u6587\u6863\u4e2d\u6211\u4eec\u5b9a\u4e49\u4e00\u4e9b\u65b0\u7684\u672f\u8bed\u6765\u7ed9middleboxes\u4e2d\u6709\u5173P2P\u7684\u884c\u4e3a\u8fdb\u884c\u5206\u7c7b\uff1a<\/p>\n

P2P-Application
\n\u5728\u8fd9\u7bc7\u6587\u6863\u4e2dP2P-Application\u88ab\u5f53\u505a\u4e00\u4e2a\u5e94\u7528\u7a0b\u5e8f\uff0c\u5728\u90a3\u4e9b\u53c2\u4e0eP2P\u8fde\u63a5\u7684\u5e76\u5728\u4e00\u4e2a\u516c\u5171\u7684\u767b\u5f55\u670d\u52a1\u5668\u6ce8\u518c\u7684\u7ec8\u7aef\u8fd0\u884c\uff0c\u53ef\u4ee5\u662f\u4e00\u4e2a\u79c1\u6709\u7aef\u70b9\uff0c\u4e5f\u53ef\u4ee5\u662f\u4e00\u4e2a\u516c\u5171\u7aef\u70b9\uff0c\u6216\u8005\u4e24\u8005\u90fd\u662f\uff0c\u5e76\u5efa\u7acb\u4e00\u4e2a\u521d\u6b65\u7684\u4f1a\u8bdd\u3002<\/p>\n

P2P-Middlebox
\nP2P- Middlebox\u5c31\u662f\u5141\u8bb8P2P\u5e94\u7528\u7a0b\u5e8f\u4ea4\u6362\u6570\u636e\u7684\u7684middlebox\u3002<\/p>\n

P2P-firewall
\n\u4e00\u4e2aP2P-\u9632\u706b\u5899\u5c31\u662f\u63d0\u4f9b\u9632\u706b\u5899\u529f\u80fd\u7684P2P- Middlebox\uff0c\u4f46\u4e0d\u5177\u5907\u5730\u5740\u6620\u5c04\u529f\u80fd\u3002<\/p>\n

P2P-NAT
\nP2P-NAT\u5c31\u662f\u63d0\u4f9bNAT\u529f\u80fd\uff0c\u4e5f\u63d0\u4f9b\u9632\u706b\u5899\u529f\u80fd\u7684P2P- Middlebox\u3002\u4e00\u53f0P2P- Middlebox\u5fc5\u987b\u4e3aUDP\u4f20\u8f93\u81f3\u5c11\u63d0\u4f9bCone NAT\u529f\u80fd\uff0c\u5141\u8bb8\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528UDP\u5efa\u7acb\u5b8c\u6574\u7684P2P\u8fde\u63a5\u3002<\/p>\n

loopback translation(\u81ea\u73af\u6620\u5c04)
\n\u5f53 \u4e00\u53f0\u4f4d\u4e8e\u79c1\u6709\u57df\u7684\u4e3b\u673a\uff0c\u5b83\u7684NAT\u8bd5\u56fe\u7528\u6b64\u4e3b\u673a\u5728\u516c\u7f51\u7684\u6620\u5c04\u5730\u5740\u8fde\u63a5\u5176\u4ed6\u4f4d\u4e8e\u540c\u6837NAT\u540e\u7684\u5176\u4ed6\u4e3b\u673a\uff0c\u76f8\u5f53\u4e8eNAT\u88c5\u7f6e\u5728\u6570\u636e\u5305\u4e0a\u505a\u4e86\u4e24\u6b21NAT\u8f6c\u6362\u3002\u5728 \u6570\u636e\u62a5\u5230\u8fbe\u76ee\u6807\u4e3b\u673a\u4e4b\u524d\uff0c\u6e90\u4e3b\u673a\u7684\u79c1\u6709\u7aef\u70b9\u88ab\u8f6c\u6362\u6210NAT\u5206\u914d\u7684\u516c\u5171\u7aef\u70b9\uff0c\u7136\u540e\u628a\u76ee\u6807\u4e3b\u673a\u7684\u516c\u5171\u7aef\u70b9\u8f6c\u6362\u6210\u76ee\u6807\u4e3b\u673a\u7684\u79c1\u6709\u7aef\u70b9\u3002\u6211\u4eec\u5728\u4e0a\u9762\u63d0\u5230\u7684\u5730\u5740\u8f6c\u6362 \u7528\u4e00\u53f0NAT\u88c5\u7f6e\u5b8c\u6210\u5c31\u79f0\u4e3a”Loopback translation”\u3002<\/p>\n

3. \u7528middleboxes\u8fdb\u884cP2P\u901a\u8baf\u7684\u6280\u672f
\n\u8fd9\u6bb5\u6587\u7ae0\u8be6\u7ec6\u7684\u56de\u987e\u4e00\u4e0b\u4f7f\u7528\u73b0\u6709\u7684middlebox\u5b9e\u73b0P2P\u901a\u8baf\u7684\u6280\u672f\uff0c\u4e3b\u8981\u4ece\u5e94\u7528\u7a0b\u5e8f\u6216\u534f\u8bae\u8bbe\u8ba1\u4e0a\u6765\u8ff0\u8bf4\u3002<\/p>\n

3.1 Relaying(\u4f20\u8f93)
\n\u6700\u53ef\u9760\u7684\uff0c\u4f46\u662f\u6548\u7387\u6700\u4f4e\u7684\uff0c\u5b9e\u73b0P2P\u901a\u8baf\u7684\u65b9\u6cd5\u5c31\u662f\u5728\u4f20\u8f93\u8fc7\u7a0b\u4e2d\uff0c\u628aP2P\u901a\u8baf\u770b\u6210\u5411C\/S\u901a\u8baf\u7684 \u7f51\u7edc\u4e00\u6837\u3002\u4f8b\u5982\uff0c\u63a8\u60f32\u4e2a\u5ba2\u6237\u4e3b\u673a\uff0cA\u548cB\uff0c\u5404\u81ea\u53d1\u8d77\u4e00\u4e2aTCP\u6216UDP\u7684\u8fde\u63a5\uff0c\u8fde\u63a5\u5230\u4e00\u4e2a\u5927\u5bb6\u90fd\u77e5\u9053\u7684\u62e5\u6709\u56fa\u5b9aIP\u5730\u5740\u7684\u670d\u52a1\u5668S\u4e0a\u3002\u5ba2\u6237\u4e3b\u673a\u90fd\u5728\u5404\u81ea \u7684\u79c1\u6709\u7f51\u7edc\u4e2d\uff0c\u4f46\u662f\u5b83\u4eec\u5404\u81ea\u7684middlebox\u4e0d\u5141\u8bb8\u81ea\u5df1\u7684\u5ba2\u6237\u7aef\u53ef\u4ee5\u76f4\u63a5\u548c\u5176\u5b83\u4e3b\u673a\u8fde\u63a5\u3002
\nServer S
\n|
\n|
\n+———————-+———————-+
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nNAT A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 NAT B
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nClient A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Client B<\/p>\n

\u4e0d\u80fd\u76f4\u63a5\u8fde\u63a5\uff0c\u4e24\u4e2a\u5ba2\u6237\u7aef\u5c31\u4f7f\u7528S\u670d\u52a1\u5668\u8fdb\u884c\u6d88\u606f\u7684\u4f20\u9012\u3002\u4f8b\u5982\uff0c\u8981\u53d1\u9001\u4e00\u6761\u4fe1\u606f\u5230\u5ba2\u6237\u7aefB\uff0c\u5ba2\u6237\u7aefA\u4ee5C\/S\u8fde\u63a5\u65b9\u5f0f\u7b80\u5355\u7684\u53d1\u9001\u4e00\u6761\u4fe1\u606f\u5230S\u670d\u52a1\u5668\uff0c\u7136\u540eS\u670d\u52a1\u5668\u4f7f\u7528\u5df2\u7ecf\u548c\u5ba2\u6237\u7aefB\u5efa\u7acb\u7684C\/S\u8fde\u63a5\u53d1\u9001\u8fd9\u6761\u4fe1\u606f\u5230\u5ba2\u6237\u7aefB\u3002<\/p>\n

\u8fd9\u79cd\u65b9\u6cd5\u7684\u4f18\u52bf\u5728\u4e8e\u53ea\u8981\u4e24\u4e2a\u5ba2\u6237\u7aef\u90fd\u8fde\u5728\u670d\u52a1\u5668\u4e0a\uff0c\u5b83\u5c31\u662f\u6709\u6548\u7684\u3002\u5b83\u7684\u660e\u663e\u7f3a\u70b9\u662f\u5b83\u9700\u8981\u4e86\u670d\u52a1\u5668\u7684\u5904\u7406\u5e76\u5360\u7528\u4e86\u5e26\u5bbd\uff0c\u800c\u4e14\u5373\u4f7f\u670d\u52a1\u5668\u7684\u7f51\u7edc\u72b6\u51b5\u826f\u597d\uff0c\u4e5f\u6709\u4e00\u5b9a\u7684\u901a\u8baf\u6ede\u540e\u95ee\u9898\u3002TRUN\u534f\u8bae[TURN]\u5b9a\u4e49\u4e86\u8fd9\u79cdP2P\u5e94\u7528\u7684\u76f8\u5173\u65b9\u6cd5\u3002
\n3.2 \u9006\u5411\u8fde\u63a5 (Connection reversal)
\n\u7b2c\u4e8c\u79cd\u6280\u672f\u662f\u5728\u53ea\u6709\u4e00\u4e2a\u5ba2\u6237\u4f4d\u4e8emiddlebox\u540e\u7684\u6761\u4ef6\u4e0b\u8fd0\u7528\u7684\u3002\u4e3e\u4f8b\u6765\u8bf4, \u63a8\u60f3\u5ba2\u6237A\u5728 NAT \u540e\u9762\u4f46\u662f\u5ba2\u6237 B \u6709\u4e00\u4e2a\u5168\u7403\u6709\u6548\u7684 IP \u5730\u5740, \u53c2\u7167\u4e0b\u9762\u56fe\u8868\uff1a<\/p>\n

Server S
\n18.181.0.31:1235
\n|
\n|
\n+———————-+———————-+
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nNAT A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n155.99.25.11:62000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nClient A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Client B
\n10.0.0.1:1234\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 138.76.29.7:1234<\/p>\n

\u5ba2\u6237A\u6709\u4e00\u4e2a\u79c1\u6709IP\u5730\u574010.0.0.1\uff0c\u5e76\u4e14\u4e00\u4e2a\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528TCP\u7aef\u53e31234\u3002\u8fd9\u4e2a\u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668S\u7684\u516c\u7f51IP\u5730\u5740 18.181.0.31\u548c\u7aef\u53e31235\u5efa\u7acb\u4e86\u4e00\u4e2a\u8fde\u63a5\u3002NAT A\u4e3a\u4e86\u5ba2\u6237\u7aefA\u548c\u670d\u52a1\u5668S\u7684\u4f1a\u8bdd\uff0c\u4e34\u65f6\u5206\u914d\u4e86\u4e00\u4e2a\u7ec8\u7aef\u5730\u5740\uff0c\u5176TCP\u7aef\u53e362000\uff0c\u5b83\u81ea\u5df1\u7684IP\u5730\u5740\u662f155.99.25.11\uff1a\u56e0\u6b64\uff0c\u670d\u52a1\u5668S\u8ba4\u4e3a\u5ba2 \u6237\u7aefA\u7528\u7684\u662fIP\u5730\u5740155.99.25.11\uff0c\u7aef\u53e3\u662f62000\u3002\u7136\u800c\uff0c\u5ba2\u6237\u7aefB\u6709\u7740\u81ea\u5df1\u7684\u56fa\u5b9aIP\u5730\u5740\uff0c138.76.29.7\uff0c\u5e76\u4e14\u5728\u5b83\u4e0a\u9762\u7684 P2P\u5e94\u7528\u7a0b\u5e8f\u53ef\u4ee5\u5728\u7aef\u53e31234\u63a5\u6536TCP\u8fde\u63a5\u3002<\/p>\n

\u73b0\u5728\u63a8\u60f3\u5ba2\u6237\u7aefB\u60f3\u8981\u4e0e\u5ba2\u6237\u7aefA\u5efa\u7acb\u4e00\u4e2aP2P\u8fde\u63a5\u4f1a\u8bdd\u3002B\u53ef\u80fd\u7528\u5ba2\u6237\u7aefA\u672c\u8eab\u7684\u5730\u5740\uff0c\u537310.0.0.1:1234\uff0c\u4e5f\u53ef\u80fd\u7528\u5728\u670d\u52a1\u5668S\u4e0a\u5f97\u5230 \u5230\u7684\u5730\u5740\uff0c155,99.25.11:62000\uff0c\u53bb\u5c1d\u8bd5\u8fde\u63a5\u3002\u7136\u800c\u65e0\u8bba\u5728\u54ea\u4e00\u79cd\u60c5\u51b5\u4e0b\uff0c\u8fde\u63a5\u90fd\u4f1a\u5931\u8d25\u3002\u7b2c\u4e00\u79cd\u60c5\u51b5\u4e0b\uff0c\u6307\u5411IP\u5730\u574010.0.0.1\u7684\u901a \u8baf\u5305\u4f1a\u88ab\u4e22\u5f03\uff0c\u56e0\u4e3a10.0.0.1\u4e0d\u662f\u4e00\u4e2a\u516c\u7f51\u56fa\u5b9aIP\u5730\u5740\u3002\u7b2c\u4e8c\u79cd\u60c5\u51b5\u4e0b\uff0c\u6765\u81ea\u5ba2\u6237\u7aefB\u7684TCP SYN\u8bf7\u6c42\u5305\u5c06\u4f1a\u5230\u8fbeNAT A\u768462000\u7aef\u53e3\uff0c\u4f46NAT A\u5c06\u4f1a\u62d2\u7edd\u8fd9\u4e2a\u8bf7\u6c42\uff0c\u56e0\u4e3aNAT A\u53ea\u5141\u8bb8\u5411\u5916\u53d1\u9001\u6570\u636e\u3002<\/p>\n

\u5728\u5c1d\u8bd5\u548c\u5ba2\u6237\u7aefA\u5efa\u7acb\u76f4\u63a5\u8fde\u63a5\u5931\u8d25\u540e\uff0c\u5ba2\u6237\u7aefB\u4f1a\u5229\u7528\u670d\u52a1\u5668S\u4f20\u9012\u4e00\u4e2a\u8bf7\u6c42\uff0c\u8ba9\u5ba2\u6237\u7aefA\u53bb\u4e3b\u52a8\u8fde\u63a5\u5ba2\u6237\u3002\u5ba2\u6237\u7aefA\u5728\u901a\u8fc7\u670d\u52a1\u5668S\u63a5\u6536\u5230\u4f20\u9012\u7684\u8bf7\u6c42 \u540e\uff0c\u4f1a\u4f7f\u7528\u5ba2\u6237\u7aefB\u7684\u516c\u5171IP\u5730\u5740\u548c\u7aef\u53e3\u5efa\u7acb\u4e00\u4e2aTCP\u8fde\u63a5\u3002 \u56e0\u4e3a\u8fd9\u4e2a\u8fde\u63a5\u662f\u5728\u9632\u706b\u5899\u5185\u90e8\u53d1\u8d77\u7684\uff0c\u6240\u4ee5NAT A\u5141\u8bb8\u8fd9\u4e2a\u8fde\u63a5\u5efa\u7acb\uff0c\u800c\u5ba2\u6237\u7aefB\u4e5f\u80fd\u63a5\u6536\u8fd9\u4e2a\u8fde\u63a5\uff0c\u56e0\u4e3a\u5b83\u5e76\u4e0d\u5904\u4e8emiddlebox\u540e\u9762\u3002\u5f53\u524d\u5b9e\u73b0P2P\u7cfb\u7edf\u7684\u4e00\u79cd\u6280\u672f\uff0c\u5b83\u6709\u4e00\u4e2a\u4e3b\u8981\u7684\u5c40\u9650\u6027\uff0c\u5c31\u662f\u5b83 \u53ea\u80fd\u5141\u8bb8P2P\u4e2d\u4e00\u65b9\u5728NAT\u540e\u9762\uff1a\u800c\u4e24\u65b9\u90fd\u5728NAT\u540e\u9762\u7684\u60c5\u51b5\u662f\u5f88\u5e38\u89c1\u7684\uff0c\u8fd9\u79cd\u65b9\u6cd5\u5c31\u4f1a\u5931\u8d25\u3002\u56e0\u4e3a\u8fd9\u79cd\u9006\u5411\u8fde\u63a5\u5e76\u4e0d\u662f\u89e3\u51b3\u95ee\u9898\u7684\u666e\u904d\u65b9\u6cd5\uff0c\u901a\u5e38\u4e0d\u63a8\u8350\u8fd9 \u4e2a\u65b9\u6cd5\u3002\u5e94\u7528\u7a0b\u5e8f\u53ef\u4ee5\u9009\u62e9\u8bd5\u4e00\u8bd5\u9006\u5411\u8fde\u63a5\uff0c\u4f46\u5f53”\u5411\u524d”\u6216”\u9006\u5411”\u90fd\u4e0d\u80fd\u5efa\u7acb\u8fde\u63a5\u65f6\uff0c\u5e94\u7528\u7a0b\u5e8f\u5e94\u8be5\u80fd\u591f\u81ea\u52a8\u7684\u53ef\u4ee5\u9009\u62e9\u53e6\u5916\u7684\u8fde\u63a5\u673a\u5236\uff0c\u6bd4\u5982 relaying(\u53733.1\u8bf4\u7684)\u3002<\/p>\n

3.3 UDP hole punching
\n\u7b2c\u4e09\u79cd\u6280\u672f\uff0c\u4e5f\u662f\u8fd9\u7bc7\u6587\u7ae0\u7684\u4e00\u4e2a\u91cd\u8981\u70b9\u4e4b\u4e00\uff0c\u5c31\u662f\u88ab\u79f0\u4e3a”UDP Hole Punching”\u7684\u6280\u672f\u3002\u5f53\u4e24\u4e2a\u9700\u8981\u901a\u8baf\u7684\u4e3b\u673a\u53ef\u80fd\u90fd\u5728middlebox\u540e\u9762\u7684\u65f6\u5019\uff0cUDP hole punching\u4f9d\u8d56\u4e8econe NAT\u548c\u666e\u901a\u9632\u706b\u5899\u7684\u4e00\u4e9b\u7279\u6027\uff0c\u5141\u8bb8\u5408\u9002\u7684P2P\u5e94\u7528\u7a0b\u5e8f\u4ee5”punch holes”\u65b9\u5f0f\u901a\u8fc7middlebox\u5e76\u4e14\u5efa\u7acb\u5f7c\u6b64\u4e4b\u95f4\u76f4\u63a5\u7684\u8fde\u63a5\u3002\u8fd9\u79cd\u6280\u672f\u5728RFC 3027[NAT- PORT]\u76845.1\u8282\u4e2d\u7b80\u8981\u7684\u63d0\u53ca\uff0c\u5e76\u4e14\u5728\u82f1\u7279\u7f51[KEGEL]\u975e\u8bc1\u5b9e\u7684\u63d0\u5230\uff0c\u4e5f\u5728\u6700\u8fd1\u7684\u4e00\u4e9b\u534f\u8bae[TEREDO, ICE]\u4e2d\u7528\u5230\u3002\u6b63\u5982\u540d\u5b57\u4e2d\u7684\u6240\u63d0\u5230\u7684\uff0c\u8fd9\u79cd\u6280\u672f\u53ea\u80fd\u7528\u4e8eUDP\u8fde\u63a5\u3002<\/p>\n

\u6211\u4eec\u5c06\u4f1a\u8003\u8651\u4e24\u4e2a\u7279\u522b\u60c5\u51b5\uff0c\u5e76\u4e14\u8003\u8651\u5e94\u7528\u7a0b\u5e8f\u5982\u4f55\u5b8c\u5584\u7684\u5904\u7406\u4e24\u8005\u4e4b\u95f4\u7684\u63e1\u624b\u8fde\u63a5\u3002\u7b2c\u4e00\u79cd\u60c5\u51b5\u4e0b\uff0c\u4e5f\u662f\u8f83\u4e3a\u666e\u901a\u7684\u60c5\u51b5\uff0c\u4e24\u4e2a\u5728\u4e0d\u901a\u7684NAT\u540e\u9762\u7684\u5ba2 \u6237\u7aef\u8981\u6c42\u76f4\u63a5\u7684\u8fdb\u884cP2P\u8fde\u63a5\u3002\u7b2c\u4e8c\u79cd\u60c5\u51b5\uff0c\u4e24\u53f0\u5ba2\u6237\u7aef\u4f4d\u4e8e\u540c\u4e00\u4e2aNAT\u540e\u9762\uff0c\u4f46\u4e0d\u80fd\u80af\u5b9a(\u4e24\u53f0\u5ba2\u6237\u7aef\u4f4d\u4e8e\u540c\u4e00\u4e2aNAT\u540e\u9762)\u3002<\/p>\n

3.3.1 \u4f4d\u4e8e\u4e0d\u540cNAT\u540e\u9762(Peers behind different NATs)
\n\u5047\u8bbe\u5ba2\u6237\u7aefA\u548cB\u90fd\u6709\u81ea\u5df1\u7684\u79c1\u6709IP\u5730 \u5740\uff0c\u4e5f\u90fd\u4f4d\u4e8e\u4e0d\u540c\u7684NAT\u540e\u9762\u3002P2P\u5e94\u7528\u7a0b\u5e8f\u5728A\u3001B\u548c\u670d\u52a1\u5668S\u4e0a\u8fd0\u884c\uff0c\u7528\u7684\u90fd\u662fUDP\u7aef\u53e31234\u3002A\u548cB\u5404\u81ea\u548c\u670d\u52a1\u5668S\u5efa\u7acbUDP\u901a\u8baf\u8fde\u63a5\uff0c\u4f7f NAT A\u4e3aA\u7684\u8fde\u63a5\u5206\u914d\u4e00\u4e2a\u81ea\u5df1\u7684\u516c\u5171\u7aef\u53e362000\uff0c\u800cNAT B\u4e3aB\u7684\u8fde\u63a5\u5206\u914d\u7684\u662f31000\u7aef\u53e3\u3002<\/p>\n

Server S
\n18.181.0.31:1234
\n|
\n|
\n+———————-+———————-+
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nNAT A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 NAT B
\n155.99.25.11:62000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 138.76.29.7:31000
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nClient A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Client B
\n10.0.0.1:1234\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 10.1.1.3:1234<\/p>\n

\u73b0\u5728\u63a8\u60f3\u4e00\u4e0b\uff0c\u5ba2\u6237\u7aefA\u60f3\u8981\u76f4\u63a5\u548cB\u5efa\u7acb\u4e00\u4e2aUDP\u901a\u8baf\u4f1a\u8bdd\u3002\u5047\u8bbeA\u7b80\u5355\u7684\u53d1\u4e00\u4e2aUDP\u4fe1\u606f\u5305\u5230B\u7684\u516c\u5171\u5730\u5740 138.76.29.7:31000\uff0c\u7136\u800cNAT B\u5c06\u4f1a\u4e22\u5f03\u8fd9\u4e9b\u8fdb\u5165\u7684\u6570\u636e\u4fe1\u606f(\u9664\u975e\u5b83\u662f\u4e00\u4e2aFULL cone NAT)\uff0c\u539f\u56e0\u662fNAT B\u548cS\u5df2\u7ecf\u5efa\u7acb\u7684\u5916\u90e8\u4f1a\u8bdd\uff0c\u800cA\u53d1\u9001\u7684\u4fe1\u606f\u4e2d\u7684\u6e90\u5730\u5740\u548c\u7aef\u53e3\u53f7\u662f\u548cS\u4e0d\u5339\u914d\u7684(\u53ef\u4ee5\u53c2\u7167\u4e00\u4e0b\u4e0a\u9762\u7684\u5185\u5bb9\uff0c\u5339\u914d\u624d\u80fd\u63a5\u53d7)\u3002\u540c\u6837\uff0c\u5047\u5982B\u53d1\u9001\u4e00\u4e2a\u6761UDP\u6570 \u636e\u5305\u7ed9A\u7684\u516c\u7f51\u5730\u5740\uff0cNAT A\u4e5f\u4f1a\u4e22\u5f03\u3002<\/p>\n

\u4f46\u662f\uff0c\u5047\u8bbeA\u53d1\u51fa\u4e00\u4e2aUDP\u6570\u636e\u4fe1\u606f\u7ed9B\u7684\u516c\u7f51IP\u5730\u5740\uff0c\u540c\u65f6\u4e5f\u901a\u8fc7\u670d\u52a1\u5668S\u4f20\u9012\u4e00\u4e2a\u8bf7\u6c42\u7ed9B\uff0c\u8981\u6c42B\u4e5f\u53d1\u4e00\u4e2aUDP\u4fe1\u606f\u7ed9A\u7684\u516c\u7f51IP\u5730\u5740\u3002A \u76f4\u63a5\u5411B\u7684\u516c\u5171IP\u5730\u5740(138.76.29.7:31000)\u53d1\u9001\u7684\u6570\u636e\u5305\u4f1a\u8ba9NAT A\u5728A\u7684\u79c1\u6709\u5730\u5740\u548cB\u7684\u516c\u7f51\u5730\u5740\u4e4b\u95f4\u5efa\u7acb\u4e86\u4e00\u4e2a\u65b0\u7684\u8fde\u63a5\u4f1a\u8bdd\u3002\u540c\u65f6\uff0cB\u5230A\u7684\u516c\u7f51\u5730\u5740(155.99.25.11:62000)\u7684\u4fe1\u606f\u4f1a\u5bfc\u81f4NAT B\u5728B\u7684\u79c1\u6709\u5730\u5740\u548cA\u7684\u516c\u5171\u5730\u5740\u4e4b\u95f4\u5efa\u7acb\u4e00\u4e2a\u65b0\u7684\u8fde\u63a5\u4f1a\u8bdd\u3002\u4e00\u65e6\u8fd9\u79cd\u65b0\u7684UDP\u8fde\u63a5\u5728\u4e24\u8005\u4e4b\u95f4\u5efa\u7acb\u8d77\u6765\uff0c\u5ba2\u6237\u7aefA\u548cB\u5c31\u4e0d\u9700\u8981\u670d\u52a1\u5668S\u7684”\u4ecb\u7ecd”\u5c31\u80fd\u5f7c\u6b64 \u76f4\u63a5\u901a\u8baf\u4e86\u3002<\/p>\n

UDP hole punching\u6280\u672f\u6709\u51e0\u4e2a\u5f88\u6709\u7528\u7684\u7279\u70b9\u3002\u4e00\u65e6\u5728\u4e24\u4e2a\u4f4d\u4e8emiddlebox\u540e\u9762\u7684\u5ba2\u6237\u7aef\u5efa\u7acb\u4e86\u4e00\u4e2a\u76f4\u63a5\u7684P2P\u8fde\u63a5\uff0c\u5728\u8fde\u63a5\u4e2d\u7684\u4efb\u4f55\u4e00\u65b9\u90fd\u53ef\u4ee5\u626e\u6f14\u4e00 \u4e2a”\u4ecb\u7ecd\u4eba”\u7684\u89d2\u8272\uff0c\u4f9d\u6b21\u7ee7\u7eed\u548c\u53e6\u4e00\u4e2a\u5ba2\u6237\u7aef\u5efa\u7acb\u8fde\u63a5\uff0c\u51cf\u5c11\u4e86\u6700\u521d\u7684\u670d\u52a1\u5668S\u7684\u8d1f\u62c5\u3002\u5982\u679c\u8bf4\u6709[STUN]\u7684\u8bdd\uff0c\u5047\u5982\u4e24\u4e2a\u4e2d\u7684\u4efb\u610f\u4e00\u4e2a\u6216\u4e24\u4e2a\u90fd\u78b0\u5de7\u4e0d\u5728 middlebox\u540e\u9762\uff0c\u4e0a\u8ff0\u5e94\u7528\u7a0b\u5e8f\u5c06\u540c\u6837\u53ef\u4ee5\u5efa\u7acbP2P\u901a\u8baf\u901a\u9053\uff0c\u5e94\u7528\u7a0b\u5e8f\u4e0d\u9700\u8981\u5c1d\u8bd5\u660e\u786emiddlebox\u7684\u7c7b\u578b\u3002Hole punching\u6280\u672f\u751a\u81f3\u53ef\u4ee5\u81ea\u52a8\u7684\u8fd0\u7528\u5728\u591a\u7ea7NAT\u4e0b\u9762\uff0c\u591a\u91cdNAT\u5c31\u662f\u90a3\u4e9b\u5ba2\u6237\u7aef\u9700\u8981\u7ecf\u5386\u591a\u7ea7\u5730\u5740\u8f6c\u6362\u624d\u80fd\u8fdb\u5165\u516c\u7f51\u3002<\/p>\n

3.3.2 \u4f4d\u4e8e\u540c\u4e00NAT\u540e(Peers behind the same NAT)
\n\u73b0\u5728\u8003\u8651\u4e24\u53f0\u5ba2\u6237\u7aef(\u4f46\u5e76\u4e0d\u786e\u5b9a)\u90fd\u5728\u540c\u4e00\u4e2aNAT\u540e\u9762\u7684\u60c5\u51b5\uff0c\u56e0\u6b64\u4f1a\u6709\u79c1\u6709IP\u5730\u5740\u7a7a\u95f4\u3002\u5ba2\u6237\u7aefA\u4e0e\u670d\u52a1\u5668S\u5efa\u7acb\u4e00\u4e2aUDP\u4f1a\u8bdd\uff0cNAT\u4f1a\u5206\u914d\u4e00\u4e2a\u516c\u5171\u7aef\u53e362000\u3002\u5ba2\u6237\u7aefB\u4e0e\u670d\u52a1\u5668S\u4e5f\u5efa\u7acb\u4e00\u4e2a\u7b80\u5355\u7684\u8fde\u63a5\uff0cNAT\u4e3a\u6b64\u5206\u914d\u4e00\u4e2a\u516c\u5171\u7aef\u53e362001\u3002<\/p>\n

Server S
\n18.181.0.31:1234
\n|
\n|
\nNAT
\nA-S 155.99.25.11:62000
\nB-S 155.99.25.11:62001
\n|
\n+———————-+———————-+
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nClient A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Client B
\n10.0.0.1:1234\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 10.1.1.3:1234<\/p>\n

\u5047\u60f3A\u548cB\u4f7f\u7528UDP hole punching\u6280\u672f\u4e0e\u670d\u52a1\u5668S\u7684\u5efa\u7acb\u4e00\u4e2a\u5916\u90e8\u7684\u901a\u8baf\u8def\u7ebf\u505a\u4e3a\u4e2d\u95f4\u4ecb\u7ecd\u3002\u7136\u540eA\u548cB\u5c06\u53ef\u4ee5\u901a\u8fc7\u670d\u52a1\u5668S\u5f97\u5230\u5404\u81ea\u516c\u5171IP\u5730\u5740\u548c\u7aef\u53e3\u53f7\uff0c\u7136\u540e\u4f7f\u7528\u8fd9\u4e9b\u5730\u5740\u5404 \u81ea\u5411\u5bf9\u65b9\u53d1\u9001\u6570\u636e\u3002\u4e24\u4e2a\u5ba2\u6237\u80fd\u591f\u4ee5\u8fd9\u79cd\u65b9\u5f0f\u5f7c\u6b64\u901a\u8baf\uff0c\u53ea\u8981NAT\u4e0d\u4ec5\u4ec5\u5141\u8bb8\u5916\u7f51\u4e0a\u7684\u4e3b\u673a\u53ef\u4ee5\u548c\u5185\u7f51\u4e0a\u7684\u4e3b\u673a\u8fdb\u884cUDP\u4f20\u8f93\u4f1a\u8bdd\uff0c\u4e5f\u53ef\u4ee5\u5141\u8bb8\u5185\u7f51\u4e0a\u7684\u4e3b\u673a\u53ef \u4ee5\u548c\u5176\u4ed6\u5185\u7f51\u7684\u4e3b\u673a\u8fdb\u884cUDP\u4f1a\u8bdd\u3002\u6211\u4eec\u5728”loopback translation”\u4e2d\u8bbe\u8ba1\u5230\u8fd9\u79cd\u60c5\u51b5\uff0c\u56e0\u4e3a\u6765\u81ea\u79c1\u6709\u7f51\u7edc\u7684\u6570\u636e\u5305\u5230\u8fbeNAT\u540e\uff0c\u4f1a”looped back”\u5230\u79c1\u6709\u7f51\u7edc\u4e0a\u5c31\u8c61\u4ece\u516c\u7f51\u6765\u7684\u4e00\u6837\u3002\u4f8b\u5982\uff0c\u5f53A\u5411B\u7684\u516c\u5171IP\u5730\u5740\u53d1\u9001\u4e00\u4e2aUDP\u5305\uff0c\u8fd9\u4e2a\u5305\u7684\u5305\u5934\u6709\u4e00\u4e2a\u6e90IP\u5730\u5740\u548c\u7aef\u53e3\uff0c\u662f 10.0.0.1:1234\uff0c\u800c\u76ee\u7684\u5730\u5740\u662f155.99.25.11.62001\u3002NAT\u63a5\u53d7\u5230\u8fd9\u4e2a\u5305\uff0c\u4f1a\u628a\u6e90\u5730\u5740\u8f6c\u6362(\u6620\u5c04)\u4e3a 155.99.25.11:62000(\u5c31\u662fA\u7684\u516c\u7f51\u5730\u5740)\uff0c\u628a\u76ee\u7684\u5730\u5740\u8f6c\u6362\u4e3a10.1.1.3:1234\uff0c\u7136\u540e\u53d1\u7ed9B\u3002\u5373\u4f7fNAT\u652f\u6301\u56de\u73af\u6620\u5c04\uff0cNAT \u7684\u8f6c\u6362\u548c\u53d1\u9001\u6b65\u9aa4\u770b\u4e0a\u53bb\u662f\u591a\u4f59\u7684\uff0c\u5728A\u548cB\u901a\u8baf\u65f6\u4f3c\u4e4e\u4e3aNAT\u6dfb\u52a0\u4e86\u6f5c\u5728\u7684\u8d1f\u62c5\u3002<\/p>\n

\u8fd9\u4e2a\u95ee\u9898\u7684\u89e3\u51b3\u65b9\u6cd5\u662f\u76f4\u63a5\u7684\u3002\u5f53A\u548cB\u4e00\u5f00\u59cb\u5728\u670d\u52a1\u5668S\u4e0a\u4ea4\u6362\u5730\u5740\u4fe1\u606f\u65f6\uff0c\u5b83\u4eec\u5c31\u53ef\u4ee5\u5305\u542b\u4ed6\u4eec\u81ea\u5df1\u7684IP\u5730\u5740\u548c\u7aef\u53e3\u53f7\uff0c\u5e76\u4e14\u662f\u53ef\u89c1\u7684\uff0c\u5bf9\u670d\u52a1\u5668S \u4e5f\u662f\u53ef\u89c1\u7684\u3002\u5ba2\u6237\u7aef\u6839\u636e\u5b83\u4eec\u5f97\u5230\u7684\u5730\u5740\u540c\u65f6\u5f00\u59cb\u5411\u5bf9\u65b9\u53d1\u6570\u636e\u5305\uff0c\u5e76\u5efa\u7acb\u6210\u529f\u7684\u901a\u8baf\u3002\u5047\u5982\u8fd9\u4e24\u4e2a\u5ba2\u6237\u7aef\u90fd\u5728\u540c\u4e00NAT\u540e\u9762\uff0c\u6570\u636e\u5305\u8c61\u901a\u8baf\u4e00\u5f00\u59cb\u5c31\u80fd\u76f4\u63a5\u5230 \u8fbe\uff0c\u800c\u4e0d\u9700\u8981\u901a\u8fc7NAT\u5c31\u80fd\u5efa\u7acb\u76f4\u63a5\u8fde\u63a5\u3002\u5047\u5982\u8fd9\u4e24\u4e2a\u5ba2\u6237\u7aef\u4f4d\u4e8e\u4e0d\u540c\u7684NAT\u540e\uff0c\u5230\u8fbe\u5f7c\u6b64\u79c1\u6709\u5730\u5740\u7684\u6570\u636e\u5305\u4f1a\u88ab\u4e22\u5f03\uff0c\u4f46\u662f\u5ba2\u6237\u7aef\u53ef\u4ee5\u901a\u8fc7\u5404\u81ea\u7684\u516c\u5171\u5730\u5740\u6765 \u5efa\u7acb\u8fde\u63a5\u3002\u91cd\u8981\u7684\u662f\u8fd9\u4e9b\u6570\u636e\u5305\u9700\u8981\u901a\u8fc7\u4e00\u4e9b\u65b9\u6cd5\u53bb\u9274\u522b\uff0c\u7136\u800c\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0cA\u53d1\u5230B\u7684\u79c1\u6709\u5730\u5740\u7684\u6570\u636e\u5305\u5b8c\u5168\u6709\u53ef\u80fd\u5230\u8fbeA\u79c1\u7f51\u5185\u5176\u4ed6\u65e0\u5173\u7684\u7ec8\u7aef\uff0cB\u53d1\u5230A \u7684\u5305\u4e5f\u662f\u8fd9\u6837\u3002<\/p>\n

3.3.3 Peers separated by multiple NATs(\u591a\u7ea7NAT)
\n\u5728\u6709\u591a\u91cdNAT\u8bbe\u5907\u7684\u62d3\u6251\u7ed3\u6784\u4e2d\uff0c\u5982\u679c\u6ca1\u6709\u4e00\u4e9b\u62d3\u6251\u7684\u77e5\u8bc6\uff0c\u5728\u4e24\u4e2a\u5ba2\u6237\u7aef\u4e4b\u95f4\u5efa\u7acb\u7406\u60f3\u7684P2P\u94fe\u8def\u662f\u4e0d\u53ef\u80fd\u7684\u3002\u770b\u770b\u4e0b\u9762\u7684\u4e3e\u7684\u4f8b\u5b50\u3002<\/p>\n

Server S
\n18.181.0.31:1234
\n|
\n|
\nNAT X
\nA-S 155.99.25.11:62000
\nB-S 155.99.25.11:62001
\n|
\n|
\n+———————-+———————-+
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nNAT A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 NAT B
\n192.168.1.1:30000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 192.168.1.2:31000
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nClient A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Client B
\n10.0.0.1:1234\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 10.1.1.3:1234<\/p>\n

\u5047\u8bbeNAT X\u662f\u7531\u4e00\u4e2a\u82f1\u7279\u7f51\u670d\u52a1\u63d0\u4f9b\u8005(ISP)\u8bbe\u7f6e\u7684\u4e00\u4e2a\u5927\u578bNAT\uff0c\u5728\u4e00\u4e9b\u516c\u7f51IP\u5730\u5740\u4e0a\u62e5\u6709\u8bb8\u591a\u7528\u6237\uff0cNAT A\u548cB\u662f\u5c0f\u7528\u6237\u7fa4\u7684NAT\u7f51\u5173\uff0c\u7531ISP\u7684\u7528\u6237\u81ea\u5df1\u72ec\u81ea\u914d\u7f6e\uff0c\u6709\u5404\u81ea\u7684\u79c1\u6709\u7f51\u7edc\u548c\u7528\u6237\u7fa4\uff0c\u4f7f\u7528\u7684\u662fISP\u63d0\u4f9b\u7684IP\u5730\u5740\u3002\u53ea\u6709SERVER S\u548cNAT X\u6709\u81ea\u5df1\u5168\u7403\u56fa\u5b9a\u7684IP\u5730\u5740\uff0c\u800cNAT A\u548cB\u7528\u7684”\u516c\u5171”IP\u5730\u5740\u5b9e\u9645\u4e0a\u662fISP\u5730\u5740\u57df\u4e2d\u79c1\u6709\u5730\u5740\uff0c\u800c\u5ba2\u6237\u7aefA\u548cB\u7684\u5730\u5740\u5bf9NAT A\u548cB\u6765\u8bf4\u4e5f\u662f\u79c1\u6709\u7684\u5730\u5740\u3002\u6bcf\u5f53\u5ba2\u6237\u7aef\u9700\u8981\u548c\u670d\u52a1\u5668S\u5efa\u7acb\u4e00\u4e2a\u5916\u90e8\u7684\u8fde\u63a5\uff0c\u90fd\u4f1a\u5bfc\u81f4NAT A\u548cB\u548c\u5ba2\u6237\u7aef\u5efa\u7acb\u4e00\u4e2a\u5355\u72ec\u7684\u516c\u5171\/\u79c1\u6709\u8fde\u63a5\uff0c\u7136\u540e\u8ba9NAT X\u4e3a\u6bcf\u4e2a\u8fde\u63a5\u4f1a\u8bdd\u5efa\u7acb\u4e00\u4e2a\u516c\u5171\/\u79c1\u6709\u8fde\u63a5\u3002<\/p>\n

\u73b0\u5728\u63a8\u60f3\u5ba2\u6237A\u548cB\u5c1d\u8bd5\u5efa\u7acb\u4e00\u4e2a\u76f4\u63a5\u7684P2P UDP\u8fde\u63a5\u3002\u5bf9\u5ba2\u6237\u7aefA\u6765\u8bf4\uff0c\u6700\u4f73\u7684\u65b9\u6cd5\u662f\u53d1\u9001\u4e00\u4e2a\u6570\u636e\u4fe1\u606f\u5230\u5ba2\u6237\u7aefB\u5728NAT B\u4e0a\uff0c\u5c5e\u4e8eISP\u7684\u5730\u5740\u57df\u7684\u516c\u5171IP\u5730\u5740192.168.1.2:31000\uff0c\u5bf9\u5ba2\u6237\u7aefB\u6765\u8bf4\u5c31\u662f\u53d1\u4fe1\u606f\u5230A\u5728NAT A\u7684\u516c\u5171IP\u5730\u5740192.168.1.1:30000(\u539f\u6587\u662fNAT B\uff0c\u662f\u4e0d\u662f\u7b14\u8bef\uff0c\u8fd8\u662f\u6211\u7406\u89e3\u6709\u95ee\u9898\uff1f)\u3002\u4e0d\u5e78\u7684\u662f\uff0cA\u548cB\u5e76\u6ca1\u6709\u77e5\u9053\u8fd9\u4e9b\u5730\u5740\u7684\u65b9\u6cd5\uff0c\u56e0\u4e3a\u670d\u52a1\u5668S\u53ea\u80fd\u770b\u5230\u5ba2\u6237\u7aef”\u5168\u5c40”\u7684\u516c\u5171IP\u5730\u5740\uff0c\u5c31\u662f 155.99.25.11:62000\u548c155.99.25.11:62001\u3002\u751a\u81f3\u5f53A\u548cB\u6709\u67d0\u4e9b\u65b9\u6cd5\u53ef\u4ee5\u5f97\u5230\u8fd9\u4e9b\u5730\u5740\uff0c\u4f46\u4ed6\u4eec\u4f9d\u7136\u4e0d\u80fd\u4fdd\u8bc1\u8fd9\u4e9b\u5730\u5740\u662f \u6709\u7528\u7684\uff0c\u56e0\u4e3a\u8fd9\u4e9b\u7531ISP\u7684\u79c1\u6709\u5730\u5740\u57df\u5206\u914d\u7684\u5730\u5740\u53ef\u80fd\u4e0e\u5ba2\u6237\u81ea\u5df1\u5206\u914d\u7684\u79c1\u6709\u5730\u5740\u7531\u51b2\u7a81\u3002\u5ba2\u6237\u7aef\u56e0\u6b64\u6ca1\u6709\u9009\u62e9\u53ea\u80fd\u4f7f\u7528\u7531\u670d\u52a1\u5668S\u77e5\u9053\u7684\u516c\u5171IP\u5730\u5740\u6765\u901a\u8baf\uff0c \u5e76\u4e14\u4f9d\u8d56NAT X\u6765\u63d0\u4f9bloopback translation\u3002<\/p>\n

3.3.4 Consistent prot binddings(\u4fdd\u6301\u7aef\u53e3\u7ed1\u5b9a)
\nhole punching \u6280\u672f\u6709\u4e00\u4e2a\u9700\u8981\u6ce8\u610f\u7684\u5730\u65b9\uff1a\u5b83\u53ea\u80fd\u5de5\u4f5c\u5728\u4e24\u53f0NAT\u90fd\u662fcone NAT(\u6216\u6ca1\u6709NAT \u9632\u706b\u5899)\u7684\u60c5\u51b5\u4e0b\uff0c\u53ea\u8981UDP\u7aef\u53e3\u8fd8\u5728\u4f7f\u7528\uff0c\u5b83\u5c31\u9700\u8981\u4fdd\u6301\u4e00\u4e2a\u56fa\u5b9a\u7684\u7aef\u53e3\u628a\u4e00\u4e2a\u7ed9\u5b9a(\u79c1\u6709IP\uff0c\u79c1\u6709UDP\u7aef\u53e3)\u548c\u4e00\u4e2a(\u516c\u5171IP\uff0c\u516c\u5171UDP\u7aef\u53e3)\u7ed1 \u5b9a\u3002\u8c61\u5bf9\u79f0NAT\u4e00\u6837\uff0c\u4e3a\u6bcf\u4e2a\u65b0\u7684\u8fde\u63a5\u4f1a\u8bdd\u5206\u914d\u4e00\u4e2a\u65b0\u7684\u516c\u5171\u7aef\u53e3\uff0c\u5bf9\u4e00\u4e2aUDP\u5e94\u7528\u7a0b\u5e8f\u6765\u8bf4\uff0c\u4e3a\u4e86\u548c\u4e0d\u540c\u7684\u5916\u90e8\u901a\u8baf\u91cd\u7528\u4e00\u4e2a\u5df2\u7ecf\u5b58\u5728\u7684\u5730\u5740\u8f6c\u6362\u662f\u4e0d\u53ef\u4ee5 \u7684\u3002(\u8fd9\u8fb9\u7a0d\u5fae\u6709\u70b9\u7cca\u6d82\uff0c\u518d\u591a\u770b\u770b\u3002) \u65e2\u7136cone NAT\u8fd0\u7528\u662f\u76f8\u5f53\u666e\u904d\u7684\uff0cUDP hole punching\u6280\u672f\u5e94\u7528\u7684\u4e5f\u76f8\u5f53\u5e7f\u6cdb\uff0c\u4f46\u662f\u8fd8\u6709\u4e00\u5c0f\u90e8\u5206\u662f\u5bf9\u7b49NAT\u914d\u7f6e\uff0c\u56e0\u6b64\u4e0d\u80fd\u652f\u6301\u8fd9\u79cd\u6280\u672f\u3002
\n3.4 UDP port number prediction<\/p>\n

\u6709\u5173UDP hole punching\u6280\u672f\u5728\u4e0a\u9762\u5df2\u7ecf\u88ab\u8ba8\u8bba\u8fc7\uff0c\u5b83\u53ef\u4ee5\u5141\u8bb8\u5728\u4e00\u4e9b\u5bf9\u7b49NAT\u5b58\u5728\u7684\u5730\u65b9\u4e5f\u80fd\u5efa\u7acbP2P UDP\u8fde\u63a5\u4f1a\u8bdd\u3002\u8fd9\u79cd\u65b9\u6cd5\u6709\u65f6\u88ab\u79f0\u4e3a”N+1″\u6280\u672f [BIDIR ]\u5e76\u4e14\u7531Takeda[SYM-STUN]\u8be6\u7ec6\u4ecb\u7ecd\u3002\u8fd9\u79cd\u65b9\u6cd5\u5206\u6790NAT\u7684\u5de5\u4f5c\u65b9\u5f0f\u5e76\u4e14\u8bd5\u56fe\u9884\u6d4b\u5b83\u4e3a\u5c06\u6765\u7684\u8fde\u63a5\u4f1a\u8bdd\u5206\u914d\u7684\u516c\u5171\u7aef\u53e3\u3002\u518d\u6b21\u8003\u8651\u90a3\u4e24\u4e2a\u5ba2\u6237\u7684 \u72b6\u6001\uff0cA\u548cB\uff0c\u5728\u5404\u81ea\u5206\u5f00\u7684NAT\u540e\u9762\uff0c\u5df2\u7ecf\u4e0e\u4e00\u53f0\u62e5\u6709\u6c38\u4e45\u5730\u5740\u7684\u670d\u52a1\u5668S\u5efa\u7acb\u4e86UDP\u8fde\u63a5\u3002
\nServer S
\n18.181.0.31:1234
\n|
\n|
\n+———————-+———————-+
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nSymmetric NAT A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Symmetric NAT B
\nA-S 155.99.25.11:62000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 B-S 138.76.29.7:31000
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nClient A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Client B
\n10.0.0.1:1234\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 10.1.1.3:1234<\/p>\n

NAT A\u5206\u914d\u4e00\u4e2a\u5c5e\u4e8e\u81ea\u5df1\u7684UDP\u7aef\u53e362000\u4ee5\u5728A\u548cS\u4e4b\u95f4\u5efa\u7acb\u901a\u8baf\u8fde\u63a5\uff0c\u800cNAT B\u5206\u914d\u4e00\u4e2a31000\u7aef\u53e3\u7528\u4e8e\u5728B\u548cS\u4e4b\u95f4\u5efa\u7acb\u8fde\u63a5\u3002\u901a\u8fc7\u4e0e\u670d\u52a1\u5668\u7684\u901a\u8baf\uff0cA\u548cB\u53ef\u4ee5\u4ece\u670d\u52a1\u5668S\u4e0a\u5f97\u5230\u5bf9\u65b9\u7684\u516c\u5171IP\u5730\u5740\u548c\u7aef\u53e3\u53f7\u3002\u5ba2\u6237\u7aefA\u73b0\u5728\u53d1\u9001\u4e00\u4e2a UDP\u6570\u636e\u5305\u5230\u5730\u5740138.76.29.7\uff0c\u7aef\u53e331001(\u6ce8\u610f\u7aef\u53e3\u6570\u76ee\u7684\u589e\u52a0)\uff0c\u800c\u5ba2\u6237\u7aefB\u540c\u65f6\u53d1\u9001\u4e00\u4e2a\u6570\u636e\u5305\u5230\u5730\u5740\u7684155,99.25.11\uff0c\u7aef \u53e362001\u4e0a\u3002\u5982\u679cNAT A\u548cB\u4f9d\u6b21\u4e3a\u65b0\u7684\u8fde\u63a5\u5206\u914d\u7aef\u53e3\uff0c\u5982\u679c\u4eceA-S\u548cB-S\u8fde\u63a5\u5efa\u7acb\u540e\u6ca1\u8fc7\u591a\u5c11\u65f6\u95f4\uff0c\u90a3\u5728A\u548cB\u4e4b\u95f4\u7684\u4e00\u4e2a\u53cc\u5411\u901a\u8baf\u901a\u9053\u5c31\u53ef\u4ee5\u5de5\u4f5c\u8d77\u6765\u3002A\u5230B\u7684\u6570\u636e\u5305\u8ba9NAT A\u5efa\u7acb\u4e00\u4e2a\u65b0\u7684\u8fde\u63a5\uff0cNAT A(\u6240\u671f\u671b\u7684)\u5206\u914d\u4e00\u4e2a\u516c\u5171\u7aef\u53e362001\uff0c\u56e0\u4e3a\u4e4b\u524dA\u548cS\u7684\u8fde\u63a5\u4f1a\u8bdd\u7528\u768462000\u7aef\u53e3\uff0c\u63a5\u4e0b\u6765\u5c31\u662f62001\u3002\u540c\u6837\u7684\uff0cB\u5230A\u7684\u6570\u636e\u5305\u5c06\u8ba9NAT B\u6253\u5f00\u4e00\u4e2a\u65b0\u8fde\u63a5\uff0c\u5e76\u5c06(\u4e5f\u662f\u6240\u671f\u671b\u7684)\u5206\u914d\u4e00\u4e2a\u7aef\u53e331001\u3002\u5982\u679c\u5ba2\u6237\u7aef\u53ef\u4ee5\u6b63\u786e\u7684\u9884\u6d4b\u5230NAT\u4e3a\u65b0\u7684\u8fde\u63a5\u5206\u914d\u7684\u7aef\u53e3\uff0c\u4e00\u6761\u53cc\u5411\u7684UDP\u901a\u8baf\u901a\u9053\u5c31\u4f1a \u8c61\u5982\u4e0b\u56fe\u6240\u793a\u4e00\u6837\u5efa\u7acb\u8d77\u6765\u3002<\/p>\n

Server S
\n18.181.0.31:1234
\n|
\n|
\n+———————-+———————-+
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nNAT A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 NAT B
\nA-S 155.99.25.11:62000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 B-S 138.76.29.7:31000
\nA-B 155.99.25.11:62001\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 B-A 138.76.29.7:31001
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\n|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |
\nClient A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Client B
\n10.0.0.1:1234\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 10.1.1.3:1234
\n\u663e\u800c\u6613\u89c1\u6709\u5f88\u591a\u60c5\u51b5\u90fd\u80fd\u5bfc\u81f4\u8fd9\u79cd\u65b9\u6cd5\u5931\u8d25\u3002\u5047\u5982\u4efb\u610f\u4e00\u4e2a\u9884\u6d4b\u7684\u7aef\u53e3\u78b0\u5de7\u5df2\u7ecf\u88ab\u5176\u4ed6\u65e0\u5173\u7684\u8fde\u63a5\u5360\u7528\uff0cNAT\u5c06\u4f1a\u9519\u8fc7\u6b63\u786e\u7684\u7aef\u53e3\uff0c\u8fde\u63a5\u5c1d\u8bd5\u4e5f \u5c06\u5931\u8d25\u3002\u5047\u5982\u4efb\u610f\u4e00\u4e2aNAT\u6709\u65f6\u6216\u8005\u603b\u662f\u9009\u62e9\u975e\u8fde\u7eed\u7684\u7aef\u53e3\u53f7\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u4e5f\u5c06\u5931\u8d25\u3002\u5047\u5982\u5728A(B)\u5efa\u7acb\u4e86\u5b83\u548cS\u7684\u8fde\u63a5\u4e4b\u540e\uff0c\u4f46\u5728\u53d1\u9001\u7b2c\u4e00\u4e2a\u6570\u636e\u5305\u5230B(A) \u4e4b\u524d\uff0c\u4e00\u4e2a\u4e0d\u540c\u7684\u5ba2\u6237\u7aef\u5728NAT(\u4e5f\u6216\u8005B)\u6253\u5f00\u4e00\u4e2a\u65b0\u7684\u5916\u90e8\u8fde\u63a5\u5230\u4efb\u4f55\u5916\u90e8\u4e3b\u673a\uff0c\u65e0\u5173\u7684\u5ba2\u6237\u7aef\u4f1a\u4e0d\u6ce8\u610f\u7684”\u5077”\u4e86(A TO B\u6216\u8005B TO A)\u6240\u8981\u6c42\u7684\u7aef\u53e3\u3002\u56e0\u6b64\u5728\u4efb\u4e00NAT\u90fd\u5305\u542b\u4e0d\u6b62\u4e00\u53f0\u5ba2\u6237\u7aef\u65f6\uff0c\u8fd9\u79cd\u65b9\u6cd5\u5f88\u5c11\u4f7f\u7528\u3002<\/p>\n

\u5b9e\u9645\u4e0a\uff0c\u5982\u679c\u90a3\u4e9bNAT\u662fcone NAT\uff0c\u6216\u8005\u4e00\u4e2a\u662fcone NAT\uff0c\u53e6\u4e00\u4e2a\u662f\u5bf9\u79f0NAT\uff0c\u8fd9\u79cd\u60c5\u51b5\u4e0b\u7684P2P\u5e94\u7528\u7a0b\u5e8f\u4f9d\u7136\u9700\u8981\u5de5\u4f5c\uff0c\u5e94\u7528\u7a0b\u5e8f\u9700\u8981\u5b9e\u73b0\u67e5\u660e\u5728\u4efb\u4f55\u4e00\u4e2a\u4e0a\u4e0eend [STUN]\u6709\u5173\u7684NAT\u662f\u54ea\u4e00\u949f\uff0c\u5e76\u6309\u6b64\u6765\u4fee\u6539\u5b83\u7684\u5de5\u4f5c\u65b9\u5f0f\uff0c\u8fd9\u6837\u589e\u52a0\u4e86\u7b97\u6cd5\u7684\u590d\u6742\u7a0b\u5e8f\u5e76\u8ba9\u7f51\u7edc\u53d8\u7684\u8106\u5f31\u3002\u6700\u7ec8\uff0c\u5047\u5982\u4efb\u4f55\u4e00\u65b9\u5ba2\u6237\u7aef\u57282\u7ea7\u4ee5\u4e0a\u7684NAT \u4e0b\u5e76\u4e14\u79bb\u5ba2\u6237\u7aef\u6700\u8fd1\u7684NAT\u662f\u5bf9\u79f0\u7684\uff0c\u9884\u6d4b\u7aef\u53e3\u7684\u65b9\u5f0f\u662f\u65e0\u6cd5\u5de5\u4f5c\u7684\u3002\u5bf9\u6240\u6709\u8fd9\u4e9b\u539f\u56e0\u6765\u8bf4\uff0c\u5e94\u7528\u7a0b\u5e8f\u662f\u65e0\u6cd5\u5b9e\u73b0\u8fd9\u79cd\u65b9\u6cd5\u7684\uff0c\u5728\u8fd9\u91cc\u88ab\u63d0\u53ca\u662f\u4e3a\u4e86\u5386\u53f2\u548c\u4fe1\u606f\u76ee \u7684(\u5c31\u662f\u544a\u8bc9\u5927\u5bb6\u6709\u8fd9\u4e48\u56de\u4e8b\uff0c\u6211\u60f3)<\/p>\n

3.5. Simultaneous TCP open(TCP\u540c\u65f6\u6253\u5f00)
\n\u5728\u4e00\u5bf9\u8282\u70b9\u90fd\u5728\u5df2\u5b58\u5728middlebox\u540e\uff0c\u6709\u4e00\u79cd\u5efa\u7acb\u76f4\u63a5 P2P TCP\u8fde\u63a5\u7684\u65b9\u6cd5\u6709\u65f6\u5019\u4f1a\u88ab\u4f7f\u7528\u3002\u5927\u591a\u6570TCP\u8fde\u63a5\u90fd\u662f\u4ece\u4e00\u4e2a\u7ec8\u7aef\u53d1\u4ece\u4e00\u4e2aSYN\u5305\u5230\u53e6\u4e00\u4e2a\u7ec8\u7aef\uff0c\u53e6\u4e00\u4e2a\u4e2d\u65ad\u540c\u6b65\u54cd\u5e94\u4e00\u4e2aSYN-ACK\u5305\u3002\u65e0\u8bba\u600e\u6837\uff0c\u5bf9 \u4e8e\u4e24\u4e2a\u7ec8\u7aef\u6765\u8bf4\uff0c\u540c\u65f6\u901a\u8fc7\u53d1\u9001\u540c\u6b65\u5305\u5230\u5bf9\u65b9\u7136\u540e\u7528\u4e00\u4e2aACK\u5305\u5e94\u7b54\u6765\u5efa\u7acb\u4e00\u4e2aTCP\u8fde\u63a5\u662f\u53ef\u884c\u7684\u3002\u8fd9\u79cd\u8fc7\u7a0b\u5c31\u88ab\u79f0\u4e3a”simultaneous open”(\u540c\u65f6\u6253\u5f00)<\/p>\n

\u5982\u679c\u4e00\u4e2amiddlebox\u4ece\u5c1d\u8bd5\u5efa\u7acb\u4e00\u4e2aTCP\u8fde\u63a5\u7684\u79c1\u6709\u7f51\u7edc\u7684\u5916\u9762\u63a5\u53d7\u4e00\u4e2aTCP SYN\u5305\uff0cmiddlebox\u901a\u5e38\u4ee5\u4e22\u5f03\u8fd9\u4e2aSYN\u5305\u6216\u8005\u53d1\u9001\u4e00\u4e2aTCP RST(\u8fde\u63a5\u590d\u4f4d)\u5305\u7684\u65b9\u5f0f\u6765\u62d2\u7edd\u8fd9\u4e2a\u8fde\u63a5\u5c1d\u8bd5\u3002\u4f46\u662f\uff0c\u5982\u679c\u540c\u6b65\u5305\u4e0e\u6e90\u548c\u76ee\u7684\u5730\u5740\u7aef\u53e3\u4e00\u8d77\u5230\u8fbe\uff0c\u90a3\u4e48\u4f1a\u8ba9middlebox\u76f8\u4fe1\u4e00\u4e2aTCP\u8fde\u63a5\u5df2\u7ecf\u5efa\u7acb\u8d77 \u6765\uff0c\u7136\u540emiddlebox\u5c06\u4f1a\u5141\u8bb8\u6570\u636e\u5305\u901a\u8fc7\u3002\u7279\u522b\u662f\u5982\u679cmiddlebox\u521a\u521a\u5f97\u5230\u5e76\u8f6c\u6362\u4e86\u4e00\u4e2a\u4ece\u540c\u6837\u5730\u5740\u548c\u7aef\u53e3\u6765\u7684SYN\u5305\uff0c\u5b83\u5c06\u8ba4\u4e3a\u8fde\u63a5\u662f\u6210\u7acb\u7684 \u5e76\u5141\u8bb8\u8fdb\u6765\u7684SYN\u901a\u8fc7\u3002\u5982\u679c\u5ba2\u6237\u7aefA\u548cB\u80fd\u5f7c\u6b64\u9884\u6d4b\u516c\u5171\u7aef\u53e3\uff0c\u5b83\u4eec\u5404\u81ea\u7684middlebox\u5c06\u5206\u914d\u4e0b\u4e00\u4e2aTCP\u8fde\u63a5\u7aef\u53e3\uff0c\u5982\u679c\u5176\u4e2d\u4e00\u4e2a\u5ba2\u6237\u7aef\u548c\u53e6\u4e00\u4e2a\u5ba2 \u6237\u7aef\u5efa\u7acb\u4e00\u4e2a\u5916\u90e8\u7684TCP\u8fde\u63a5\uff0c\u53ef\u4ee5\u5728\u5bf9\u65b9SYN\u5230\u8fbe\u672c\u5730middlebox\u4e4b\u524d\u5c31\u53d1\u9001SYN\u5305\u901a\u8fc7\u5b83\u672c\u5730\u81ea\u5df1\u7684middlebox\uff0c\u90a3\u4e48P2P TCP\u8fde\u63a5\u5c31\u53ef\u4ee5\u5de5\u4f5c\u4e86\u3002<\/p>\n

\u4ee4\u4eba\u9057\u61be\u7684\u662f\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u4e5f\u53ef\u80fd\u6bd4\u4e0a\u9762\u8bf4\u7684UDP\u7aef\u53e3\u53f7\u9884\u6d4b\u65b9\u6cd5\u66f4\u8106\u5f31\u5e76\u5bf9\u65f6\u6548\u66f4\u52a0\u654f\u611f\u3002\u9996\u5148\uff0c\u9664\u975e\u5728\u8fdb\u884cTCP\u8fde\u63a5\u65f6\uff0c\u4e24\u4e2a middleboxes\u662f\u7b80\u5355\u7684\u9632\u706b\u5899\u6216\u8005cone NAT\uff0c\u5728\u5404\u81ea\u5c1d\u8bd5\u731c\u6d4b\u516c\u5171\u7aef\u53e3\u53f7\u6765\u8ba9NAT\u5206\u914d\u65b0\u7684\u8fde\u63a5\u65f6\uff0c\u548c\u4e0a\u9762(UDP\u7aef\u53e3\u9884\u6d4b)\u8bf4\u5230\u7684\u5b8c\u5168\u4e00\u6837\u7684\u4e8b\u60c5\u4f1a\u5bfc\u81f4\u8fde\u63a5\u5931\u8d25\u3002\u53e6\u5916\uff0c\u5982\u679c\u6709\u4e00\u65b9\u7684\u5ba2\u6237\u53d1\u9001 \u7684\u540c\u6b65\u5305\u592a\u8fc5\u901f\u7684\u5230\u8fbe\u5bf9\u9762\u7684middlebox\uff0c\u8fdc\u7aefmiddlebox\u53ef\u80fd\u4f1a\u7528\u4e00\u4e2aRST\u5305\u62d2\u7eddSYN\u5305\uff0c\u63a5\u4e0b\u6765\u5c31\u4f1a\u5bfc\u81f4\u672c\u5730\u7684middlebox\u5173\u95ed \u5bf9\u8bdd\u5e76\u4e14\u5728\u5c06\u6765SYN\u91cd\u53d1\u65f6\u4f7f\u7528\u4e86\u76f8\u540c\u4f46\u65e0\u7528\u7684\u7aef\u53e3\u53f7\u3002\u6700\u7ec8\uff0c\u5bf9simultaneous open\u7684\u652f\u6301\u4f5c\u4e3a\u4e00\u4e2aTCP\u7684\u7279\u6b8a\u5e94\u7528\uff0c\u6ca1\u6709\u5728\u5e7f\u6cdb\u7684\u7cfb\u7edf\u4e2d\u88ab\u4f7f\u7528\u3002\u56e0\u6b64\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u4e5f\u53ea\u4e3a\u5386\u53f2\u56e0\u7d20\u5728\u8fd9\u91cc\u88ab\u540c\u6837\u63d0\u53ca\uff1b\u5b83\u4e0d\u5efa\u8bae\u88ab\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528\u3002\u5728\u73b0\u6709 NAT\u4e0a\u60f3\u8981\u5b9e\u73b0P2P\u76f4\u63a5\u901a\u8baf\u7684\u5e94\u7528\u7a0b\u5e8f\u5e94\u8be5\u4f7f\u7528UDP\u3002<\/p>\n

4. Application design guidelines(\u5e94\u7528\u7a0b\u5e8f\u8bbe\u8ba1\u601d\u8def)<\/p>\n

4.1 What works with P2P middleboxes(\u5982\u4f55\u548cP2P middlebox\u4e00\u8d77\u5de5\u4f5c)
\n\u65e2\u7136UDP hole punching\u662f\u5728\u4e24\u4e2a\u90fd\u4f4d\u4e8eNAT\u540e\u7684\u4e3b\u673a\u4e4b\u95f4\u5efa\u7acbP2P\u76f4\u63a5\u901a\u8baf\u65b9\u6cd5\u4e2d\u6700\u6709\u6548\u7387\u7684\u4e00\u4e2a\uff0c\u5e76\u4e14\u5b83\u53ef\u4ee5\u5728\u591a\u79cd\u73b0\u6709NAT\u4e0a\u4f7f\u7528\uff0c\u5982\u679c\u8981\u6c42\u5efa\u7acb\u6709\u6548\u7684P2P\u901a\u8baf\uff0c\u901a\u5e38\u5efa\u8bae\u8fd9\u79cd\u65b9\u6cd5\uff0c\u4f46\u5f53\u76f4\u63a5\u901a\u8baf\u4e0d\u80fd\u5efa\u7acb\u65f6\uff0c\u5c31\u5f97\u4f9d\u9760\u7b80\u5355\u7684\u4f20\u64ad\u3002(\u8fd8\u4e0d\u600e\u4e48\u660e\u767d)<\/p>\n

4.2 Peers behind the same NAT(\u4e3b\u673a\u5728\u540c\u4e00\u4e2aNAT\u540e\u9762)
\n\u5b9e\u9645\u4e0a\u6709\u76f8\u5f53\u6570\u91cf\u7684\u7528\u6237\u4e0d\u6b622\u4e2aIP\u5730\u5740\uff0c\u4f1a\u67093\u4e2a\u6216\u8005\u66f4\u591a\u7684IP\u5730\u5740\u3002\u8fd9\u6837\u7684\u8bdd\uff0c\u544a\u8bc9\u767b\u5f55\u670d\u52a1\u5668\u7a76\u7adf\u662f\u54ea\u4e00\u4e2a\u5730\u5740\u53d8\u7684\u5c31\u6709\u4e9b\u56f0\u96be\u4e86\u3002\u56e0\u6b64\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u5e94\u7528\u7a0b\u5e8f\u5e94\u8be5\u53d1\u9001\u5b83\u6240\u6709\u7684IP\u5730\u5740\u3002<\/p>\n

4.3 Peer discovery(\u4e3b\u673a\u53d1\u73b0)<\/p>\n

\u5e94\u7528\u7a0b\u5e8f\u4f1a\u53d1\u9001\u4e00\u4e9b\u6570\u636e\u5305\u5230\u51e0\u4e2a\u5730\u5740\uff0c\u4ee5\u53d1\u73b0\u54ea\u4e00\u4e2a\u5730\u5740\u662f\u6700\u5408\u9002\u7684\uff0c\u5e94\u7528\u7a0b\u5e8f\u53ef\u80fd\u53d8\u6210(\u540e\u9762\u7684\u4e0d\u592a\u660e\u767d\uff0c\u81ea\u5df1\u7406\u89e3\u5427\uff0csorry)\uff0c \u7531\u4e8e\u4e3b\u673a\u53ef\u80fd\u4f1a\u4e0d\u6070\u5f53\u7684\u9009\u62e9\u4e00\u4e2a\u8def\u7531\u5730\u5740\u5f53\u505a\u4e00\u4e2a\u5185\u90e8\u5c40\u57df\u7f51(\u4f8b\u598211.0.1.1\uff0c\u5df2\u7ecf\u88abDOD\u7f51\u7edc\u5206\u914d\uff0cDOD\u662f\u4e00\u79cd\u7f51\u7edc\u6a21\u578b)\u3002\u56e0\u6b64\u5e94\u7528\u7a0b\u5e8f\u5e94\u8be5\u5c0f \u5fc3\u7684\u53d1\u9001\u63a8\u6d4b\u7684\u547c\u53eb\u5305\u3002
\n\u7533\u8bf7\u628a\u5305\u9001\u5230\u51e0\u5730\u5740\u53d1\u73b0\uff0c \u54ea\u4e00\u4e2a\u9002\u5b9c\u9002\u5408\u4e00\u89c4\u5b9a\u8d35\u65cf\u4f7f\u7528\u53ef\u80fd\u6210\u4e3a\u4e00\u4e2a\u4e71\u6254\u51c0\u4ef7\u7684” \u7a7a\u95f4\u5e9f\u54c1”\u7684\u663e\u8457\u7684\u6e90\u5934\uff0c<\/p>\n

4.4 TCP P2P applications (TCP P2P\u5e94\u7528\u7a0b\u5e8f)<\/p>\n

\u88ab\u7a0b\u5e8f\u5458\u4eec\u5e7f\u6cdb\u4f7f\u7528\u7684SOCKET API\uff0c\u5e38\u7528\u4e8eC\/S\u7ed3\u6784\u5e94\u7528\u8bbe\u8ba1\u4e2d\u3002\u5728\u5b83\u7684\u901a\u5e38\u4f7f\u7528\u65b9\u5f0f\u4e2d\uff0c\u4e00\u4e2aSOCKET\u80fd\u7ed1\u5b9a\u4e00\u4e2aTCP\u6216UDP\u7aef\u53e3\u3002\u4e00\u4e2a\u5e94\u7528\u7a0b\u5e8f\u4e0d\u4f1a\u88ab\u5141\u8bb8\u7528\u540c\u6837\u7684\u7aef\u53e3 (TCP or UDP)\u548c\u591a\u4e2aSOCKET\u7ed1\u5b9a\u6765\u548c\u591a\u4e2a\u5916\u90e8\u4e3b\u673a\u540c\u65f6\u5efa\u7acb\u8fde\u63a5(\u6216)\u7528\u4e00\u4e2aSOCKET\u5728\u7aef\u53e3\u4e0a\u76d1\u542c\u800c\u5176\u4ed6SOCKET\u6765\u5efa\u7acb\u5916\u90e8\u8fde\u63a5\u3002\u4f46\u662f\u4e0a\u8ff0\u5355\u4e2a SOCKET\u7684\u7aef\u53e3\u7ed1\u5b9a\u9650\u5236\u5728UDP\u4e0a\u4e0d\u662f\u95ee\u9898\uff0c\u56e0\u4e3aUDP\u662f\u57fa\u4e8e\u6570\u636e\u62a5\u6587\u7684\u534f\u8bae\u3002UDP P2P\u5e94\u7528\u7a0b\u5e8f\u8bbe\u8ba1\u8005\u53ef\u4ee5\u7528recvfrom()\u548csendto()\u51fd\u6570\u6765\u8ba9\u4e00\u4e2aSOCKET\u4e0d\u4ec5\u53d1\u9001\u800c\u4e14\u53ef\u4ee5\u4ece\u591a\u4e2a\u4e3b\u673a\u4e0a\u63a5\u53d7\u6570\u636e\u62a5\u6587\u3002<\/p>\n

\u8fd9\u4e0d\u662fTCP\u5177\u6709\u7684\u60c5\u51b5\u3002\u7531\u4e8eTCP\uff0c\u6bcf\u4e2a\u8f93\u5165\u548c\u8f93\u51fa\u8fde\u63a5\u90fd\u8981\u548c\u4e00\u4e2a\u5355\u72ec\u7684SOCKET\u6709\u8054\u7cfb\u3002Linux Sockets API\u7528SO_REUSEADDR\u9009\u9879\u7684\u5e2e\u52a9\u6765\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898(\u662f\u4e0d\u662f\u5e94\u8be5\u8fd9\u4e48\u8bf4\uff1f)\uff0c\u8fd9\u4e2a\u9009\u9879\u597d\u8c61\u4e0d\u8d77\u4f5c\u7528\uff0c\u4f46\u53ef\u4ee5
\n(\u5728 \u6807\u51c6Single Unix\u91cc\u6ca1\u6709\u8fd9\u4e2a\u51fd\u6570)\u3002Win32 API\u63d0\u4f9b\u4e86\u4e00\u4e2a\u76f8\u540c\u7684\u8c03\u7528SetReuseAddress\u3002\u4f7f\u7528\u4efb\u4f55\u4e0a\u8ff0\u7684\u9009\u62e9\uff0c\u5e94\u7528\u7a0b\u5e8f\u53ef\u4ee5\u590d\u7528\u4e00\u4e2aTCP\u7aef\u53e3\u7684\u591a\u4e2aSOCKET\u3002\u5c31\u662f\u8bf4\uff0c\u53ef\u4ee5\u6253\u5f00 \u4e24\u4e2a\u7ed1\u5b9a\u5728\u540c\u6837\u7aef\u53e3\u4e0a\u7684TCP stream Socket\uff0c\u4e00\u4e2a\u7528\u4e0elisten()\uff0c\u53e6\u4e00\u4e2a\u7528\u4e0e\u5176\u5b83\u4e3b\u673aconnect()<\/p>\n

4.5 Use of midcom protocol()<\/p>\n

\u5982\u679c\u5e94\u7528\u7a0b\u5e8f\u77e5\u9053\u5b83\u4eec\u9700\u8981\u7a7f\u8d8a\u7684middlebox\u5e76\u4e14\u8fd9\u4e9bmiddlebox\u5b9e\u73b0midcom \u534f\u8bae\uff0c\u5e94\u7528\u7a0b\u5e8f\u80fd\u4f7f\u7528midcom\u534f\u8bae\u66f4\u5bb9\u6613\u7684\u7a7f\u8d8amiddlebox\u3002
\n\u4f8b \u5982\uff0cP2P\u5e94\u7528\u7a0b\u5e8f\u9700\u8981NAT middlebox\u4fdd\u6301\u7ec8\u7aef\u7aef\u53e3\u7684\u7ed1\u5b9a\u72b6\u6001\u3002\u5047\u5982middlebox\u53ef\u4ee5\u652f\u6301midcom\uff0cP2P\u5e94\u7528\u7a0b\u5e8f\u53ef\u4ee5\u63a7\u5236\u4fee\u6539\u7ed1\u5b9a\u7aef\u53e3(\u6216\u8005\u7ed1\u5b9a\u5730\u5740)\u7684\u53c2\u6570\uff0c \u4f8b\u5982\u751f\u5b58\u65f6\u95f4\uff0cmaxidletime(?)\uff0c\u56e0\u6b64\u5e94\u7528\u7a0b\u5e8f\u4e0d\u4ec5\u53ef\u4ee5\u76f4\u63a5\u7684\u8fde\u63a5\u5916\u90e8\u4e3b\u673a\u800c\u4e14\u4e5f\u53ef\u4ee5\u4ece\u5916\u90e8\u4e3b\u673a\u63a5\u53d7\u8fde\u63a5\uff1b\u8fd9\u6837\u5c31\u4e0d\u9700\u8981\u5b9a\u671f\u4fdd\u6301\u7aef\u53e3\u7ed1\u5b9a\u7684\u72b6 \u6001\u3002\u5f53\u5e94\u7528\u7a0b\u5e8f\u4e0d\u518d\u9700\u8981\u7ed1\u5b9a\uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528midcom\u534f\u8bae\u7b80\u5355\u7684\u53d6\u6d88\u7ed1\u5b9a\u3002<\/p>\n

5. NAT Design Guidelines (NAT\u8bbe\u8ba1\u6307\u5bfc)
\n\u8fd9\u90e8\u5206\u8ba8\u8bba\u7f51\u7edc\u5730\u5740\u8f6c\u6362\u7684\u8bbe\u8ba1\uff0c\u4ed6\u4eec\u4f1a\u5f71\u54cdP2P\u5e94\u7528\u7a0b\u5e8f\u3002<\/p>\n

5.1 Deprecat the use of symmetric NATs (\u4e0d\u8d5e\u6210\u4f7f\u7528\u5bf9\u7b49NAT)
\n\u5bf9\u7b49NAT\u5728\u90a3\u4e9bC\/S\u7ed3 \u6784\u7684\u5e94\u7528\u4e2d\u6bd4\u5982\u7f51\u7edc\u6d4f\u89c8\u4e2d\u5f97\u5230\u5e7f\u6cdb\u5e94\u7528\uff0c\u5b83\u4eec\u53ea\u9700\u8981\u5efa\u7acb\u4e00\u4e2a\u5411\u5916\u7684\u8fde\u63a5\u5373\u53ef\u3002\u4f46\u662f\u73b0\u5728\uff0c\u6bd4\u5982\u5b9e\u65f6\u6d88\u606f\u548c\u8bed\u97f3\u4f1a\u8bae\u7b49P2P\u5e94\u7528\u7a0b\u5e8f\u88ab\u5e7f\u6cdb\u7684\u5e94\u7528\u3002\u5bf9\u7b49NAT \u4e0d\u80fd\u652f\u6301\u4fdd\u7559\u7ec8\u7aef\u7684\u5b9a\u4e49\u5e76\u4e14\u4e0d\u9002\u7528\u4e8eP2P\u5e94\u7528\u7a0b\u5e8f\u3002\u4e0d\u5efa\u8bae\u4f7f\u7528\u5bf9\u7b49NAT\u6765\u652f\u6301P2P\u5e94\u7528\u7a0b\u5e8f\u3002
\n\u4e00\u4e2aP2P-middlebox\u5fc5\u987b\u5728UDP \u901a\u8baf\u65f6\u5177\u5907Cone NAT\u7684\u7279\u70b9\uff0c\u5141\u8bb8\u5e94\u7528\u7a0b\u5e8f\u53ef\u4ee5\u5efa\u7acb\u4f7f\u7528UDP hole punching\u6280\u672f\u5efa\u7acb\u7a33\u5b9a\u7684P2P\u8fde\u63a5\u3002\u7406\u8bba\u4e0a\uff0c\u4e00\u4e2aP2P-middlebox\u5e94\u8be5\u4e5f\u5141\u8bb8\u5e94\u7528\u7a0b\u5e8f\u65e2\u53ef\u4ee5\u7ecf\u8fc7TCP\uff0c\u4e5f\u53ef\u4ee5\u901a\u8fc7UDP\u5efa\u7acbP2P\u8fde \u63a5\u3002<\/p>\n

5.2 Add incremental cone-NAT support to symmetric NAT devices (\u589e\u52a0\u9012\u589e\u7684cone-NAT\u4ee5\u652f\u6301\u5bf9\u7b49NAT\u8bbe\u5907)<\/p>\n

\u4e00\u79cd\u53ef\u4ee5\u8ba9\u5bf9\u7b49NAT\u8bbe\u5907\u6269\u5c55\u652f\u6301P2P\u5e94\u7528\u7a0b\u5e8f\u7684\u662f\u5206\u914d\u5b83\u7684\u53ef\u8f6c\u8ba9\u7684\u7aef\u53e3\u7a7a\u95f4\uff0c\u4e3a\u4e00\u5230\u4e00\u7684\u8fde\u63a5\u9884\u8ba2\u4e00\u4e2a\u5408\u9002\u7684\u7aef\u53e3\uff0c\u4e3a\u4e00\u4e2a\u4e00\u5230\u591a\u7684\u8fde\u63a5\u9884\u8ba2\u5408\u9002\u7684\u4e00\u5957\u4e0d\u540c\u7684\u7aef\u53e3\u3002
\n\u66f4\u8fdb\u4e00\u6b65(\u672a\u6765?)\uff0c\u4e00\u4e2aNAT\u88c5\u7f6e\u53ef\u4ee5\u660e\u786e\u7684\u88ab\u90a3\u4e9bP2P\u5e94\u7528\u7a0b\u5e8f\u548c\u4e3b\u673a\u914d\u7f6e\uff0c\u56e0\u6b64NAT\u88c5\u7f6e\u53ef\u4ee5\u81ea\u52a8\u7531\u6b63\u786e\u7684\u7aef\u53e3\u6570\u636e\u5757\u6765\u5206\u914d\u4e00\u4e2aP2P\u7aef\u53e3\u3002<\/p>\n

5.3 Maintain consisten port bindings for UDP ports (\u4fdd\u6301UDP\u7aef\u53e3\u7684\u7ed1\u5b9a)
\n\u8fd9\u4efd\u8d44\u6599\u5bf9NAT\u8bbe\u8ba1\u8005\u6700\u4e3b\u8981\u548c\u6700\u91cd\u8981\u7684\u5efa\u8bae\u662fNAT\u4fdd\u6301\u4e00\u4e2a\u56fa\u5b9a\u7684\u7aef\u53e3\uff0c\u7ed1\u5b9a\u4e00\u4e2a\u7ed9\u5b9a\u7684(\u5185\u90e8IP\u5730\u5740\uff0c\u5185\u90e8UDP\u7aef\u53e3)\u548c\u4e00\u4e2a\u76f8\u5e94\u7684(\u516c\u5171IP\u5730\u5740\uff0c\u516c\u5171UDP\u7aef\u53e3)
\n\u53ea \u8981\u6709\u4efb\u4f55\u8fde\u63a5\u5b58\u5728\u5e76\u4f7f\u7528\u8fd9\u4e2a\u7aef\u53e3\u7ed1\u5b9a\uff0c\u8fd9\u4e2a\u7aef\u53e3\u7ed1\u5b9a\u5c31\u8981\u5b58\u5728\u3002\u901a\u8fc7\u68c0\u67e5\u6bcf\u4e00\u4e2a\u5305\u7684\u6e90\u548c\u76ee\u7684IP\u5730\u5740\u548c\u7aef\u53e3\u53f7\uff0cNAT\u53ef\u80fd\u4f1a\u8fc7\u6ee4\u5173\u4e8e\u6bcf\u4e00\u4e2a\u8fde\u63a5\u57fa\u7840\u7684\u6570\u636e\u5305 (? \u4ffa8\u61c2)\u3002\u5f53\u5728\u4e00\u4e2a\u79c1\u6709\u7f51\u7edc\u4e0a\u7684\u8282\u70b9\u5efa\u7acb\u4e86\u4e00\u4e2a\u65b0\u7684\u5916\u90e8\u8fde\u63a5\u65f6\uff0c\u4f7f\u7528\u4e86\u4e00\u4e2a\u73b0\u6709\u7684\u5df2\u7ecf\u8f6c\u6362\u8fc7\u7684UDP\u8fde\u63a5\u4f1a\u8bdd\u7684IP\u5730\u5740\u548cUDP\u7aef\u53e3\u53f7\uff0cNAT\u5e94\u8be5\u4fdd\u8bc1\u65b0 \u7684UDP\u8fde\u63a5\u4f5c\u4e3a\u73b0\u6709\u8fde\u63a5\u7ed9\u5b9a\u4e00\u4e2a\u540c\u6837\u7684\u516c\u5171IP\u5730\u5740\u548cUDP\u7aef\u53e3\u3002<\/p>\n

5.3.1 Preserving port numbers(\u4fdd\u6301\u7aef\u53e3\u53f7)\u00a0 (\u5c31\u662f\u5ba2\u6237\u7aef\u7528\u5565\u7aef\u53e3\uff0cNAT\u5206\u914d\u5565\u7aef\u53e3\u8fd9\u4e2a\u610f\u601d\u5427)
\n\u4e00 \u4e9bNAT\uff0c\u5f53\u5efa\u7acb\u4e00\u4e2a\u65b0\u7684UDP\u8fde\u63a5\u65f6\uff0c\u4f1a\u5c1d\u8bd5\u7ed9\u4e00\u4e2a\u76f8\u5e94\u7684\u79c1\u6709\u7aef\u53e3\u53f7\u5206\u914d\u4e00\u4e2a\u540c\u6837\u7684\u516c\u5171\u7aef\u53e3\u53f7\uff0c\u5982\u679c\u8fd9\u4e2a\u7aef\u53e3\u53f7\u78b0\u5de7\u662f\u53ef\u7528\u7684\u3002\u4f8b\u5982\uff0c\u5047\u5982\u5730\u5740\u662f 10.0.0.1\u7684\u5ba2\u6237\u7aefA\u7528\u4e00\u4e2a\u4ece\u7aef\u53e31234\u53d1\u9001\u7684\u6570\u636e\u5305\u5efa\u7acb\u4e00\u4e2a\u5916\u90e8\u7684UDP\u8fde\u63a5\uff0cNAT\u7684\u516c\u5171\u7aef\u53e31234\u78b0\u5de7\u662f\u53ef\u7528\u7684\uff0c\u90a3\u4e48NAT\u4f1a\u4e3a\u8fde\u63a5\u4f7f\u7528 NAT\u516c\u5171IP\u5730\u5740\u4e0a\u7684\u7aef\u53e3\u53f71234\u4f5c\u4e3a\u8f6c\u6362\u5ba2\u6237\u7aefA\u7684\u5730\u5740\u3002\u7531\u4e8e\u5982\u679c\u5185\u90e8\u7f51\u7edc\u7684\u6700\u591a\u4e00\u4e2a\u8282\u70b9\u6b63\u5728\u4f7f\u7528\u8fd9\u4e2a\u7aef\u53e3\u53f7\uff0c\u5b83\u662f\u5bf9\u4e00\u4e2aNAT\u4fdd\u6301\u7aef\u53e3\u552f\u4e00\u53ef\u884c\u7684 \u65b9\u6cd5\uff0c\u8fd9\u79cd\u65b9\u5f0f\u53ef\u80fd\u5bf9\u4e00\u4e9b\u5e0c\u671b\u53ea\u7528\u7279\u522b\u7684UDP\u7aef\u53e3\u53f7\u7684\u8fc7\u53bb\u7684UDP\u7a0b\u5e8f\u6709\u5e2e\u52a9\uff0c\u4f46\u4e0d\u5efa\u8bae\u5e94\u7528\u7a0b\u5e8f\u4f9d\u9760\u8fd9\u79cd\u65b9\u5f0f\u3002
\n\u53e6\u5916\uff0c \u4e00\u4e2aNAT\u4e0d\u5e94\u8be5\u5728\u4e00\u4e2a\u65b0\u8fde\u63a5\u4e2d\u4fdd\u6301\u7aef\u53e3\u53f7\uff0c\u5982\u679c\u786e\u5b9e\u5982\u6b64\u5c06\u4e0e\u4fdd\u6301\u516c\u5171\u548c\u79c1\u6709\u7ec8\u7aef\u5730\u5740\u7ed1\u5b9a\u7684\u76ee\u7684\u76f8\u62b5\u89e6\u3002\u4f8b\u5982\uff0c\u5047\u5b9a\u5ba2\u6237\u7aefA\u5728\u5185\u90e8\u76841234\u7aef\u53e3\u4e0a\u4e0e\u5916\u90e8 \u670d\u52a1\u5668S\u5efa\u7acb\u4e86\u4e00\u4e2a\u8fde\u63a5\uff0cNAT A\u5df2\u7ecf\u4e3a\u8fd9\u4e2a\u8fde\u63a5\u5206\u914d\u4e86\u516c\u5171\u7aef\u53e362000\uff0c\u56e0\u4e3a\u7aef\u53e3\u53f71234\u5728NAT\u4e0a\u6b64\u65f6\u662f\u4e0d\u53ef\u7528\u7684\u3002\u73b0\u5728\u5047\u60f3\u5728NAT\u4e0a\u7684\u7aef\u53e3\u53f71234\u540e\u6765\u53ef\u4ee5\u4f7f\u7528\u4e86\uff0c\u800c\u6b64\u65f6A \u548cS\u7684\u8fde\u63a5\u4ecd\u7136\u5b58\u5728\uff0c\u5ba2\u6237\u7aefA\u7528\u540c\u6837\u7684\u5185\u90e8\u7aef\u53e31234\u5efa\u7acb\u4e00\u4e2a\u65b0\u7684\u8fde\u63a5\u5230\u5916\u90e8\u8282\u70b9B\u4e0a\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u56e0\u4e3a\u7aef\u53e3\u7ed1\u5b9a\u5df2\u7ecf\u5728\u5ba2\u6237\u7aefA\u7684\u7aef\u53e31234\u548c NAT\u7684\u516c\u5171\u7aef\u53e362000\u4e0a\u5efa\u7acb\uff0c\u6240\u4ee5\u8fd9\u4e2a\u7ed1\u5b9a\u5e94\u8be5\u7ee7\u7eed\u4fdd\u6301\uff0c\u65b0\u8fde\u63a5\u4e5f\u5e94\u8be5\u752862000\u7aef\u53e3\u4f5c\u4e3a\u516c\u5171\u7aef\u53e3\uff0c\u6765\u5bf9\u5e94\u5ba2\u6237\u7aefA\u7684\u7aef\u53e31234\u3002NAT\u4e0d\u5e94\u8be5 \u4ec5\u4ec5\u56e0\u4e3a\u7aef\u53e31234\u53d8\u7684\u53ef\u7528\u4e86\u5c31\u4e3a\u65b0\u7684\u8fde\u63a5\u5206\u914d\u516c\u5171\u7aef\u53e31234\uff1a\u8fd9\u79cd\u7279\u70b9\u4e0d\u53ef\u80fd\u5728\u4efb\u4f55\u60c5\u51b5\u4e0b\u90fd\u5bf9\u5e94\u7528\u7a0b\u5e8f\u6709\u5e2e\u52a9\uff0c\u7531\u4e8e\u5e94\u7528\u7a0b\u5e8f\u5df2\u7ecf\u5bf9\u4e00\u4e2a\u8f6c\u6362\u7684\u7aef\u53e3\u53f7 \u8fdb\u884c\u64cd\u4f5c\uff0c\u5e76\u4e14\u5b83\u4f1a\u4e2d\u65ad\u5e94\u7528\u7a0b\u5e8f\u7528UDP hole punching\u6280\u672f\u5efa\u7acbP2P\u8fde\u63a5\u7684\u5c1d\u8bd5\u3002<\/p>\n

5.4 Maintaining consistent port bindings for TCP ports (\u4e3aTCP\u7aef\u53e3\u4fdd\u6301\u7aef\u53e3\u7ed1\u5b9a)
\n\u548cUDP\u5730\u5740\u8f6c\u6362\u7684\u7279\u70b9\u4e00\u81f4\uff0ccone NAT\u4e5f\u5e94\u8be5\u5bf9TCP\u8fde\u63a5\u4fdd\u6301\u79c1\u6709\u548c\u516c\u5171IP\u5730\u5740\uff0cTCP\u7aef\u53e3\u53f7\u7684\u7ed1\u5b9a\u4e0d\u53d8\uff0c\u5c31\u5982\u4e0a\u9762\u7684\u5173\u4e8eUDP\u63cf\u8ff0\u7684\u65b9\u5f0f\u4e00\u6837\u3002\u4fdd\u6301TCP\u7ec8\u7aef\u7ed1\u5b9a\u4e0d\u53d8\u5c06\u589e\u52a0NAT\u5bf9P2P TCP\u5e94\u7528\u7a0b\u5e8f\u5728\u4ece\u540c\u6837\u6e90\u7aef\u53e3\u5efa\u7acb\u591a\u4e2aTCP\u8fde\u63a5\u65f6\u7684\u517c\u5bb9\u6027\u3002<\/p>\n

5.5 Large timeout for P2P applications (P2P\u7a0b\u5e8f\u7684\u5927\u8d85\u65f6?)
\n\u6211\u4eec\u63a8\u8350 middlebox\u5728P2P\u5e94\u7528\u65f6\u4f7f\u7528\u7684\u6700\u5c0f\u8d85\u65f6\u5927\u7ea65\u5206\u949f(300\u79d2)\uff0c\u5373\uff0c\u5728P2P\u5e94\u7528\u65f6\u4e3a\u7aef\u53e3\u7ed1\u5b9a\u6216\u4e3a\u5206\u914d\u7aef\u53e3\u65f6\uff0c\u6765\u7ed9middlebox\u914d\u7f6e\u8fd9\u4e2a \u7a7a\u95f2\u8d85\u65f6\u65f6\u95f4\u3002\u5f53middlebox\u60ef\u7528\u76ee\u524d\u914d\u7f6e\u65f6\uff0c\u5c31\u5e38\u5e38\u5c1d\u8bd5\u4f7f\u7528\u66f4\u77ed\u7684\u65f6\u95f4\u3002\u4f46\u662f\u66f4\u77ed\u7684\u8d85\u65f6\u65f6\u95f4\u662f\u6709\u4e9b\u95ee\u9898\u7684\u3002\u8003\u8651\u4e00\u4e2a\u670916\u4e2a\u7ec8\u7aef\u8282\u70b9\u7684P2P\u5e94\u7528 \u7a0b\u5e8f\uff0c\u4ed6\u4eec\u5c06\u6bcf10\u79d2\u53d1\u7ed9\u7f51\u7edc\u4e00\u4e2a\u4fdd\u6301\u6d3b\u52a8\u72b6\u6001\u7684\u6570\u636e\u5305\u4ee5\u907f\u514dNAT\u8d85\u65f6\u3002\u8fd9\u6837\u505a\u662f\u56e0\u4e3a\u4e00\u4e2a\u53ef\u80fd\u4f1a\u4ee5middlebox\u8d85\u65f6\u65f6\u95f4\u76845\u500d\u53d1\u9001\u4fdd\u6301\u6d3b\u52a8\u7684\u6570\u636e \u5305\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4fdd\u6301\u6d3b\u52a8\u7684\u5305\u5c06\u5728\u7f51\u7edc\u4e0a\u88ab\u4e22\u5f03\u3002<\/p>\n

5.6 Support loopback translation(\u652f\u6301\u81ea\u73af\u8f6c\u6362)
\n\u6211\u4eec\u5f3a\u70c8\u5efa\u8baemiddlebox \u652f\u6301\u81ea\u73af\u8f6c\u6362\uff0c\u5141\u8bb8\u5728\u4e00\u53f0middlebox\u540e\u9762\u7684\u4e3b\u673a\u53ef\u4ee5\u548c\u5176\u5b83\u4f4d\u4e8e\u540c\u4e00middlebox\u540e\u7684\u4e3b\u673a\u901a\u8fc7\u5b83\u4eec\u7684\u53ef\u80fd\u88ab\u8f6c\u6362\u7684\u516c\u5171\u7aef\u70b9\u901a\u8baf\u3002\u652f\u6301\u81ea\u73af\u8f6c\u6362 \u662f\u76f8\u5f53\u91cd\u8981\u7684\uff0c\u7279\u522b\u662f\u5728\u90a3\u4e9b\u5927\u5bb9\u91cf\u591a\u5c42NAT\u4e2d\uff0c\u4f5c\u4e3a\u7b2c\u4e00\u7ea7\u7684NAT\u3002\u5982\u7b2c3.3.3 \u90e8\u5206\u7684\u63cf\u8ff0\uff0c\u4f4d\u4e8e\u540c\u4e00\u53f0\u4e00\u7ea7NAT\u4e0b\uff0c\u4f46\u662f\u7b2c\u4e8c\u7ea7NAT\u4e0d\u540c\u7684\u4e3b\u673a\u65e0\u6cd5\u901a\u8fc7UDP hole punching\u5f7c\u6b64\u901a\u8baf\uff0c\u5373\u4f7f\u5168\u90e8middlebox\u4fdd\u6301\u7aef\u70b9\u5728NAT\u4e0a\u7684\u6620\u5c04\u4e0d\u53d8\uff0c\u9664\u975e\u7b2c\u4e00\u7ea7NAT\u652f\u6301\u81ea\u73af\u8f6c\u6362\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

http:\/\/www.cnblogs.com\/epan\/articles\/989 … \u7ee7\u7eed\u9605\u8bfb →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[109,38],"class_list":["post-254469","post","type-post","status-publish","format-standard","hentry","category-internet","tag-nat","tag-nat-hotspot"],"_links":{"self":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts\/254469","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=254469"}],"version-history":[{"count":2,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts\/254469\/revisions"}],"predecessor-version":[{"id":254471,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=\/wp\/v2\/posts\/254469\/revisions\/254471"}],"wp:attachment":[{"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=254469"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=254469"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.zhenglei.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=254469"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}