{"id":1409,"date":"2017-10-20T14:03:06","date_gmt":"2017-10-20T06:03:06","guid":{"rendered":"http:\/\/ykyi.net\/?p=1409"},"modified":"2017-10-20T14:03:06","modified_gmt":"2017-10-20T06:03:06","slug":"%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%ab%af%e7%9a%84tcp%e6%9c%89%e5%a4%a7%e9%87%8ftime_wait%e6%80%8e%e4%b9%88%e5%8a%9e","status":"publish","type":"post","link":"https:\/\/ykyi.net\/?p=1409","title":{"rendered":"\u670d\u52a1\u5668\u7aef\u7684tcp\u6709\u5927\u91cfTIME_WAIT\u600e\u4e48\u529e"},"content":{"rendered":"

\u516c\u53f8\u7684\u7fa4\u91cc\u8ba8\u8bbatcp\u7684TIME_WAIT\u7684\u95ee\u9898\u3002TIME_WAIT\u8fd9\u4e2a\u72b6\u6001\u53ef\u662f\u9762\u8bd5\u65f6\u7ecf\u5e38\u95ee\u7684\u77e5\u8bc6\u70b9\u554a\u3002
\n\u8ba8\u8bba\u7684\u95ee\u9898\u662f\uff1a\u6709\u4e00\u4e2a\u670d\u52a1\u5668\uff0c\u5b83\u5bf9\u5916\u7f51\u63d0\u4f9b\u670d\u52a1\uff0c\u540c\u65f6\u5b83\u4f5c\u4e3a\u5ba2\u6237\u7aef\u8fde\u63a5\u5f88\u591a\u540e\u7aef\u7684\u5176\u5b83\u670d\u52a1\u5668\u3002\u8fd9\u4f4d\u540c\u4e8b\u8fde\u540e\u7aef\u5176\u5b83\u670d\u52a1\u5668\u65f6\u7528\u4e86\u77edtcp\u8fde\u63a5\u3002\u7ed3\u679c\u51fa\u73b0\u4e86\u5927\u91cf\u7684tcp TIME_WAIT\u72b6\u6001\uff0c\u541e\u5410\u91cf\u4e0a\u4e0d\u53bb\uff0c\u600e\u4e48\u529e\uff1f<\/p>\n

\u5148\u8bf4\u7ed3\u8bba\uff1a
\n1. \u5982\u679c\u8be5\u670d\u52a1\u5668\u8981\u5904\u7406\u5916\u7f51IP\u7684\u5165\u6d41\u91cf\uff0c\u90a3\u6700\u597d\u7684\u529e\u6cd5\u5e94\u8be5\u662f\u7528tcp\u957f\u94fe\u63a5\u6539\u9020\u5b83\u4e0e\u540e\u7aef\u670d\u52a1\u5668\u7684\u8fde\u63a5\u3002\u5982\u679c\u7528\u4e2d\u95f4\u4ef6\uff0c\u6bd4\u5982\u4e0azeromq\u90a3\u66f4\u7701\u5fc3\u4e86\u3002
\n2. \u5982\u679c\u4e0d\u60f3\u505a\u6539\u52a8\uff0c\u5e76\u4e14\u5728\u5e94\u7528\u5c42\u786e\u8ba4\u5df2\u7ecf\u4ea4\u4e92\u5df2\u7ecf\u5b8c\u6210\uff0c\u5219\u53ef\u4ee5\u7528shutdown()\u76f4\u63a5\u53d1RST\u7ed3\u675ftcp\u4f1a\u8bdd\uff0c\u800c\u4e0d\u8d70\u6b63\u5e38\u76844\u6b21\u6325\u624b\u3002\u67e5\u9605shutdown\u7cfb\u7edf\u8c03\u7528\u7684\u6587\u6863\u83b7\u77e5\u5982\u4f55\u53d1RST\u3002
\n3. \u5982\u679c\u8be5\u670d\u52a1\u5668\u4e0d\u9700\u8981\u5904\u7406\u5904\u7f51IP\u8bf7\u6c42\u7684\u8bdd\uff0c\u90a3\u4e48\uff0c\u542f\u7528port reuse \u5373\u6253\u5f00net.ipv4.tcp_tw_reuse\u4e0d\u4f1a\u6709\u592a\u5927\u95ee\u9898(\u5982\u679c\u5904\u7406\u5916\u7f51\u8bf7\u6c42\u5c31\u6709\u95ee\u9898\uff0c\u548cNAT\u76f8\u5173\uff0c\u89c1https:\/\/vincent.bernat.im\/en\/blog\/2014-tcp-time-wait-state-linux<\/a>)\uff0c\u6216\u8005\u66f4\u597d\u7684\uff0c\u628a\/proc\/sys\/net\/ipv4\/tcp_fin_timeout\u6539\u5c0f\uff0c\u6539\u62101\u6216\u80052\u3002\u8ba9TIME_WAIT\u53ea\u4fdd\u6301\u5f88\u77ed\u7684\u65f6\u95f4\u3002<\/p>\n

\u9996\u5148\uff0c\u9700\u8981\u77e5\u9053\u4e00\u4e2atcp\u4f1a\u8bdd\u7531 src_ip, src_port, dest_ip, dest_port \u56db\u5143\u7ec4\u786e\u5b9a\u3002
\n\u6211\u4eec\u516c\u53f8\u7684IDC\u73af\u5883\u4e2d\uff0c \u4e0a\u8ff0\u7684\u670d\u52a1\u5668\u4f5c\u4e3a\u5ba2\u6237\u7aef\u518d\u53d1\u8d77tcp\u8fde\u63a5\u8054\u540e\u7aef\u670d\u52a1\u5668\uff0c\u5219 src_ip \u56fa\u5b9a\u4e86\uff0c dest_ip\u662f\u540e\u7aef\u670d\u52a1\u5668\u7684ip, port\u662f\u540e\u7aef\u670d\u52a1\u5668\u76d1\u542c\u7aef\u53e3\u3002\u8fd9\u6837\u53ea\u6709 src_port \u662f\u53ef\u53d8\u5316\u7684\uff0c\u4f46port\u53ea\u670916\u4e2abits\u8fd8\u4e0d\u80fd\u7528well-known ports\uff0c\u8fd9\u6837\u5c31\u66f4\u5c11\u4e86\u3002<\/p>\n

\u518d\u8bf4\uff0c\u4e3b\u52a8\u5173\u95ed\u65f6\uff0ctcp\u8fde\u63a5\u9700\u8981\u8fdb\u5165TIME_WAIT\u72b6\u6001\uff0c\u4fdd\u6301\u4e24\u500dMSL\u65f6\u957f\uff0c\u662f\u4e3a\u4e86\u5904\u7406\u4e24\u79cd\u60c5\u51b5\uff1a
\n1) \u8ba9\u5f53\u524d\u8fd9\u4e2a\u4f1a\u8bdd\u7684\u8ff7\u8def\u5305\u5728\u7f51\u8def\u4e2d\u6d88\u5931\u3002\u8fd9\u6837\u4e0d\u4f1a\u5e72\u6270\u5230\u65b0\u5efa\u7684\u4f1a\u8bdd\u3002
\n2) \u786e\u4fdd\u4e3b\u52a8\u5173\u95ed\u65b9\u7684FIN-ACK\u5305\uff0c\u5982\u679c\u4e22\u5931\u7684\u8bdd\uff0c\u8fd8\u80fd\u91cd\u53d1\u3002
\n1981\u5e74\u7684TCP RFC\u4e0a\u628aMSL\u8bbe\u6210\u4e24\u5206\u949f\uff0chttps:\/\/tools.ietf.org\/html\/rfc793<\/p>\n

\n Maximum Segment Lifetime, the time a TCP segment can exist in
\n the internetwork system. Arbitrarily defined to be 2 minutes.\n<\/p><\/blockquote>\n

MSL\u8bbe\u7f6e\u8fd9\u4e48\u957f\uff0c\u56e0\u4e3a\u4ee5\u524d\u7684\u7f51\u7edc\u73af\u5883\u5dee\u554a\u3002\u4e0d\u8fc7\u73b0\u5728\u56e0\u4e3a\u79fb\u52a8\u4e92\u8054\u7f51\uff0c\u6bd4\u8f83\u5dee\u7684\u7f51\u7edc\u72b6\u6001\u4e5f\u662f\u975e\u5e38\u5e38\u89c1\u7684\u3002\u4f46RFC\u5141\u8bb8\u5b9e\u73b0\u65b9\u51cf\u5c11MSL\u503c\u3002\u4e8b\u5b9e\u4e0alinux\u7684MSL\u5199\u6b7b\u5728\u4ee3\u7801\u4e2d\u4e3a1\u5206\u949f\u5e76\u4e14\u4e0d\u53ef\u5728\u8fd0\u884c\u671f\u914d\u7f6e\u3002
\n\u5982\u679ctcp\u8fde\u63a5\u7684\u53cc\u65b9\u90fd\u5728\u6027\u80fd\u9ad8\u901f\u7a33\u5b9a\u7684\u5185\u7f51\u4e2d\uff0c\u8fd9\u4e2aMSL\u5c31\u592a\u957f\u4e86\u3002<\/p>\n

\u8c03\u8bd5\u65f6\uff0c\u8fd8\u53d1\u73b0\u5982\u679cport\u7528\u5b8c\u4e86\uff0cconnect\u7684\u65f6\u5019\u5185\u6838\u4ee3\u7801\u4f1a\u7528\u81ea\u65cb\u9501\u5fd9\u7b49\u68c0\u67e5port\u8d44\u6e90\u3002\u6709linux\u5185\u6838\u5f00\u53d1\u57fa\u7840\u7684\u5f00\u53d1\u8005\u90fd\u77e5\u9053spin_lock\u7684\u65f6\u5019\u662f\u4e0d\u4f1a\u8ba9\u51facpu\u7684\uff0c\u4e8e\u662fcpu\u5168\u88abspin_lock\u5403\u6389\u4e86\u3002\u4e00\u76f4\u8981\u7b49\u5230\u6709port\u88ab\u91ca\u653e\u3002\u518d\u540e\u6765\u53c8\u53d1\u73b0\uff0c\u5982\u679cscoket\u6ca1\u6709\u8bbe\u5b9aSO_REUSEADDR\u9009\u9879\uff0c\u5219connect()\u7cfb\u7edf\u8c03\u7528\u4f1a\u8fd4\u56deEADDRINUSE\u3002<\/p>\n

tcp\u7684\u8fde\u63a5\u53cc\u65b9\u90fd\u662f\u786e\u5b9a\u4e14\u957f\u671f\u7684\uff0c\u7528\u4ec0\u4e48tcp\u77ed\u8fde\u63a5\u5462\uff1f\uff1f\u6539\u9020\u5427~~~<\/p>\n","protected":false},"excerpt":{"rendered":"

\u516c\u53f8\u7684\u7fa4\u91cc\u8ba8\u8bbatcp\u7684TIME_WAIT\u7684\u95ee\u9898\u3002TIME_WAIT\u8fd9\u4e2a\u72b6\u6001\u53ef\u662f\u9762\u8bd5\u65f6\u7ecf\u5e38\u95ee\u7684\u77e5\u8bc6\u70b9\u554a\u3002 \u8ba8\u8bba\u7684\u95ee\u9898\u662f\uff1a\u6709\u4e00\u4e2a\u670d\u52a1\u5668\uff0c\u5b83\u5bf9\u5916\u7f51\u63d0\u4f9b\u670d\u52a1\uff0c\u540c\u65f6\u5b83\u4f5c\u4e3a\u5ba2\u6237\u7aef\u8fde\u63a5\u5f88\u591a\u540e\u7aef\u7684\u5176\u5b83\u670d\u52a1\u5668\u3002\u8fd9\u4f4d\u540c\u4e8b\u8fde\u540e\u7aef\u5176\u5b83\u670d\u52a1\u5668\u65f6\u7528\u4e86\u77edtcp\u8fde\u63a5\u3002\u7ed3\u679c\u51fa\u73b0\u4e86\u5927\u91cf\u7684tcp TIME_WAIT\u72b6\u6001\uff0c\u541e\u5410\u91cf\u4e0a\u4e0d\u53bb\uff0c\u600e\u4e48\u529e\uff1f \u5148\u8bf4\u7ed3\u8bba\uff1a 1. \u5982\u679c\u8be5\u670d\u52a1\u5668\u8981\u5904\u7406\u5916\u7f51IP\u7684\u5165\u6d41\u91cf\uff0c\u90a3\u6700\u597d\u7684\u529e\u6cd5\u5e94\u8be5\u662f\u7528tcp\u957f\u94fe\u63a5\u6539\u9020\u5b83\u4e0e\u540e\u7aef\u670d\u52a1\u5668\u7684\u8fde\u63a5\u3002\u5982\u679c\u7528\u4e2d\u95f4\u4ef6\uff0c\u6bd4\u5982\u4e0azeromq\u90a3\u66f4\u7701\u5fc3\u4e86\u3002 2. \u5982\u679c\u4e0d\u60f3\u505a\u6539\u52a8\uff0c\u5e76\u4e14\u5728\u5e94\u7528\u5c42\u786e\u8ba4\u5df2\u7ecf\u4ea4\u4e92\u5df2\u7ecf\u5b8c\u6210\uff0c\u5219\u53ef\u4ee5\u7528shutdown()\u76f4\u63a5\u53d1RST\u7ed3\u675ftcp\u4f1a\u8bdd\uff0c\u800c\u4e0d\u8d70\u6b63\u5e38\u76844\u6b21\u6325\u624b\u3002\u67e5\u9605shutdown\u7cfb\u7edf\u8c03\u7528\u7684\u6587\u6863\u83b7\u77e5\u5982\u4f55\u53d1RST\u3002 3. \u5982\u679c\u8be5\u670d\u52a1\u5668\u4e0d\u9700\u8981\u5904\u7406\u5904\u7f51IP\u8bf7\u6c42\u7684\u8bdd\uff0c\u90a3\u4e48\uff0c\u542f\u7528port reuse \u5373\u6253\u5f00net.ipv4.tcp_tw_reuse\u4e0d\u4f1a\u6709\u592a\u5927\u95ee\u9898(\u5982\u679c\u5904\u7406\u5916\u7f51\u8bf7\u6c42\u5c31\u6709\u95ee\u9898\uff0c\u548cNAT\u76f8\u5173\uff0c\u89c1https:\/\/vincent.bernat.im\/en\/blog\/2014-tcp-time-wait-state-linux)\uff0c\u6216\u8005\u66f4\u597d\u7684\uff0c\u628a\/proc\/sys\/net\/ipv4\/tcp_fin_timeout\u6539\u5c0f\uff0c\u6539\u62101\u6216\u80052\u3002\u8ba9TIME_WAIT\u53ea\u4fdd\u6301\u5f88\u77ed\u7684\u65f6\u95f4\u3002 \u9996\u5148\uff0c\u9700\u8981\u77e5\u9053\u4e00\u4e2atcp\u4f1a\u8bdd\u7531 src_ip, src_port, dest_ip, dest_port \u56db\u5143\u7ec4\u786e\u5b9a\u3002 \u6211\u4eec\u516c\u53f8\u7684IDC\u73af\u5883\u4e2d\uff0c \u4e0a\u8ff0\u7684\u670d\u52a1\u5668\u4f5c\u4e3a\u5ba2\u6237\u7aef\u518d\u53d1\u8d77tcp\u8fde\u63a5\u8054\u540e\u7aef\u670d\u52a1\u5668\uff0c\u5219 src_ip \u56fa\u5b9a\u4e86\uff0c dest_ip\u662f\u540e\u7aef\u670d\u52a1\u5668\u7684ip, port\u662f\u540e\u7aef\u670d\u52a1\u5668\u76d1\u542c\u7aef\u53e3\u3002\u8fd9\u6837\u53ea\u6709 src_port \u662f\u53ef\u53d8\u5316\u7684\uff0c\u4f46port\u53ea\u670916\u4e2abits\u8fd8\u4e0d\u80fd\u7528well-known ports\uff0c\u8fd9\u6837\u5c31\u66f4\u5c11\u4e86\u3002 \u518d\u8bf4\uff0c\u4e3b\u52a8\u5173\u95ed\u65f6\uff0ctcp\u8fde\u63a5\u9700\u8981\u8fdb\u5165TIME_WAIT\u72b6\u6001\uff0c\u4fdd\u6301\u4e24\u500dMSL\u65f6\u957f\uff0c\u662f\u4e3a\u4e86\u5904\u7406\u4e24\u79cd\u60c5\u51b5\uff1a 1) \u8ba9\u5f53\u524d\u8fd9\u4e2a\u4f1a\u8bdd\u7684\u8ff7\u8def\u5305\u5728\u7f51\u8def\u4e2d\u6d88\u5931\u3002\u8fd9\u6837\u4e0d\u4f1a\u5e72\u6270\u5230\u65b0\u5efa\u7684\u4f1a\u8bdd\u3002 2) \u786e\u4fdd\u4e3b\u52a8\u5173\u95ed\u65b9\u7684FIN-ACK\u5305\uff0c\u5982\u679c\u4e22\u5931\u7684\u8bdd\uff0c\u8fd8\u80fd\u91cd\u53d1\u3002 1981\u5e74\u7684TCP RFC\u4e0a\u628aMSL\u8bbe\u6210\u4e24\u5206\u949f\uff0chttps:\/\/tools.ietf.org\/html\/rfc793 Maximum Segment Lifetime, the time a TCP segment can exist in the internetwork system. Arbitrarily defined to be 2 minutes. MSL\u8bbe\u7f6e\u8fd9\u4e48\u957f\uff0c\u56e0\u4e3a\u4ee5\u524d\u7684\u7f51\u7edc\u73af\u5883\u5dee\u554a\u3002\u4e0d\u8fc7\u73b0\u5728\u56e0\u4e3a\u79fb\u52a8\u4e92\u8054\u7f51\uff0c\u6bd4\u8f83\u5dee\u7684\u7f51\u7edc\u72b6\u6001\u4e5f\u662f\u975e\u5e38\u5e38\u89c1\u7684\u3002\u4f46RFC\u5141\u8bb8\u5b9e\u73b0\u65b9\u51cf\u5c11MSL\u503c\u3002\u4e8b\u5b9e\u4e0alinux\u7684MSL\u5199\u6b7b\u5728\u4ee3\u7801\u4e2d\u4e3a1\u5206\u949f\u5e76\u4e14\u4e0d\u53ef\u5728\u8fd0\u884c\u671f\u914d\u7f6e\u3002 … Continue reading “\u670d\u52a1\u5668\u7aef\u7684tcp\u6709\u5927\u91cfTIME_WAIT\u600e\u4e48\u529e”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,7],"tags":[],"class_list":["post-1409","post","type-post","status-publish","format-standard","hentry","category-network","category-unix_linux"],"_links":{"self":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts\/1409","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1409"}],"version-history":[{"count":0,"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts\/1409\/revisions"}],"wp:attachment":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1409"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1409"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1409"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}