{"id":3707,"date":"2018-11-16T15:33:49","date_gmt":"2018-11-16T07:33:49","guid":{"rendered":"http:\/\/switch.linesno.com\/?p=3707"},"modified":"2018-11-16T15:33:50","modified_gmt":"2018-11-16T07:33:50","slug":"%e5%9c%a8nat%e4%b8%8btcp_tw_recycle%e5%8f%82%e6%95%b0%e8%b0%83%e6%95%b4","status":"publish","type":"post","link":"http:\/\/switch.linesno.com\/?p=3707","title":{"rendered":"\u5728NAT\u4e0btcp_tw_recycle\u53c2\u6570\u8c03\u6574"},"content":{"rendered":"<h3>\u4e00\uff0c\u6545\u969c\u63cf\u8ff0\uff1a<\/h3>\n<p>\u4ece\u6628\u5929\u5f00\u59cb\uff0c\u5728\u503c\u73ed\u7fa4\u4e2d\u9646\u7eed\u503c\u73ed\u4eba\u5458\u53cd\u6620\u7cfb\u7edf\u540e\u53f0\u5b58\u5728\u5361\u987f\u95ee\u9898\uff0c\u5982\u4e0b\u56fe\uff1a<br \/>\n<img decoding=\"async\" src=\"\" alt=\"\u8bb0\u4e00\u6b21\u7531tcp_tw_recycle\u53c2\u6570\u5f15\u53d1\u7684\u8840\u6848\" \/><br \/>\n\u800c\u4e14\u5728\u5361\u987f\u7684\u540c\u65f6\u767b\u9646\u670d\u52a1\u5668\u4e5f\u4f1a\u5361\u597d\u4e45\u3002\u6b64\u73b0\u8c61\u53ea\u5728\u4e00\u53f0\u670d\u52a1\u5668\u6709\u51fa\u73b0\u3002<\/p>\n<h3>\u4e8c\uff0c\u6545\u969c\u5206\u6790\uff1a<\/h3>\n<p>1\uff0c\u767b\u9646\u670d\u52a1\u5668\u67e5\u770b\u8d44\u6e90\u4f7f\u7528top\uff0cvmstat\u7b49\u547d\u4ee4\u67e5\u770b\u4e86\u4e00\u756a\u53d1\u73b0\u670d\u52a1\u5668\u5404\u9879\u6307\u6807\u90fd\u6ca1\u6709\u5f02\u5e38\u3002\u4e8e\u662f\u5c06\u95ee\u9898\u8f6c\u5411\u4e86\u7f51\u7edc\u5c42\u3002<br \/>\n2\uff0c\u5ba2\u6237\u7aef\u7aef\u503c\u73ed\u4eba\u5458\u53cd\u6620\u53ea\u6709\u5728\u8bbf\u95ee\u7cfb\u7edf\u540e\u53f0\u7684\u65f6\u5019\u624d\u4f1a\u51fa\u73b0\u5361\u987f\uff0c\u8bbf\u95ee\u5176\u4ed6\u7f51\u7ad9\u6b63\u5e38\u3002<br \/>\n3\uff0c\u672c\u5730\u4f7f\u7528ping\u670d\u52a1\u5668\u5916\u7f51ip\u6b63\u5e38\u8fd4\u56de\uff0c\u65e0\u4e22\u5305\uff0c\u5ef6\u8fdf\u4e5f\u6b63\u5e38\u3002<br \/>\n4\uff0c\u4f7f\u7528http-ping\u5de5\u5177\u65f6\uff0c\u95ee\u9898\u51fa\u73b0\u4e86\uff0c\u4f1a\u7ecf\u5e38\u6027\u7684\u51fa\u73b0\u8fde\u63a5\u5931\u8d25\uff1a<br \/>\n(http-ping\u5de5\u5177\u4e0b\u8f7d\u5730\u5740https:\/\/www.softpedia.com\/get\/Network-Tools\/IP-Tools\/http-ping.shtml)<br \/>\n<img decoding=\"async\" src=\"\" alt=\"\u8bb0\u4e00\u6b21\u7531tcp_tw_recycle\u53c2\u6570\u5f15\u53d1\u7684\u8840\u6848\" \/><br \/>\n\u4e3a\u4ec0\u4e48\u4f1a\u8fde\u63a5\u5931\u8d25\u5462\uff1f<br \/>\n5\uff0c\u4f7f\u7528tcpdump\u6293\u5305\u5728\u5361\u987f\u7684\u65f6\u5019\u4f1a\u6293\u5230\u5927\u91cf\u7684syn\u8bf7\u6c42\uff0c\u4f46\u670d\u52a1\u5668\u6ca1\u6709\u54cd\u5e94\uff1a<br \/>\n<img decoding=\"async\" src=\"\" alt=\"\u8bb0\u4e00\u6b21\u7531tcp_tw_recycle\u53c2\u6570\u5f15\u53d1\u7684\u8840\u6848\" \/><br \/>\n6\uff0c\u767b\u5f55\u670d\u52a1\u5668\u67e5\u770btcp\u76f8\u5173\u6570\u636e<\/p>\n<pre><code class=\"hljs perl\">$ netstat -<span class=\"hljs-keyword\">s<\/span> | <span class=\"hljs-keyword\">grep<\/span> -i <span class=\"hljs-keyword\">listen<\/span>\r\n    <span class=\"hljs-number\">326<\/span> <span class=\"hljs-keyword\">times<\/span> the <span class=\"hljs-keyword\">listen<\/span> queue of a <span class=\"hljs-keyword\">socket<\/span> overflowed\r\n    <span class=\"hljs-number\">751346<\/span> SYNs to LISTEN sockets dropped<\/code><\/pre>\n<p>\u53d1\u73b0\u5728\u5361\u987f\u65f6\u6709\u5927\u91cftcp syn\u5305\u88ab\u4e22\u5f03\uff0c\u6570\u503c\u4e00\u76f4\u5728\u589e\u957f\u3002<\/p>\n<h3>\u4e09\uff0c\u6545\u969c\u5904\u7406\uff1a<\/h3>\n<p>\u5728\u67e5\u9605\u8d44\u6599\u5e76\u7ed3\u5408\u5b9e\u9645\u60c5\u51b5\u540e\uff0c\u53d1\u73b0\u8be5\u670d\u52a1\u5668\u540c\u65f6\u542f\u7528\u4e86 tcp_timestamps\u548ctcp_tw_recycle\u53c2\u6570\u3002<br \/>\n\u540e\u60f3\u8d77\uff0c\u4e4b\u524d\u540c\u4e8b\u4e3a\u6539\u5584time_wait\u8fde\u63a5\u6570\u8fc7\u591a\u95ee\u9898\u66fe\u6539\u8fc7\u8be5\u5185\u6838\u53c2\u6570\u3002<br \/>\n\u89e3\u51b3\u529e\u6cd5\u662f\uff0c\u5173\u95edtcp_tw_recycle\uff1a<\/p>\n<pre><code class=\"hljs shell\"><span class=\"hljs-meta\">$<\/span><span class=\"bash\"> vi  \/etc\/sysctl.conf<\/span>\r\n<span class=\"hljs-meta\">#<\/span><span class=\"bash\">\u4fee\u6539\u4e3a\u5982\u4e0b<\/span>\r\nnet.ipv4.tcp_tw_recycle = 0\r\n<span class=\"hljs-meta\">#<\/span><span class=\"bash\">\u4fdd\u5b58\u9000\u51fa\uff0c\u4f7f\u4e4b\u751f\u6548<\/span>\r\n<span class=\"hljs-meta\">$<\/span><span class=\"bash\"> sysctl -p<\/span><\/code><\/pre>\n<p>\u518d\u89c2\u5bdf\uff0c\u53d1\u73b0\u670d\u52a1\u5df2\u6b63\u5e38\uff0c\u5361\u987f\u73b0\u8c61\u6d88\u5931\u3002<\/p>\n<h3>\u56db\uff0c\u603b\u7ed3\uff1a<\/h3>\n<p>\u6211\u4eec\u5148\u6765man\u4e00\u4e0b\u8fd9\u4e24\u4e2a\u53c2\u6570(man tcp)\uff1a<\/p>\n<pre><code class=\"hljs javascript\"> tcp_timestamps (<span class=\"hljs-built_in\">Boolean<\/span>; <span class=\"hljs-keyword\">default<\/span>: enabled; since Linux <span class=\"hljs-number\">2.2<\/span>)\r\n              Enable RFC <span class=\"hljs-number\">1323<\/span> TCP timestamps.<\/code><\/pre>\n<p>tcp_timestamp \u662f RFC1323 \u5b9a\u4e49\u7684\u4f18\u5316\u9009\u9879\uff0c\u4e3b\u8981\u7528\u4e8e TCP \u8fde\u63a5\u4e2d RTT(Round Trip Time) \u7684\u8ba1\u7b97\uff0c\u5f00\u542f tcp_timestamp \u6709\u5229\u4e8e\u7cfb\u7edf\u8ba1\u7b97\u66f4\u52a0\u51c6\u786e\u7684 RTT\uff0c\u4e5f\u5c31\u6709\u5229\u4e8e TCP \u6027\u80fd\u7684\u63d0\u5347\u3002\uff08\u9ed8\u8ba4\u5f00\u542f\uff09<br \/>\n\u5173\u4e8etcp_timestamps\u8be6\u60c5\u8bf7\u89c1\uff1a<a href=\"https:\/\/tools.ietf.org\/pdf\/rfc7323.pdf\" rel=\"nofollow\">https:\/\/tools.ietf.org\/pdf\/rfc7323.pdf<\/a><\/p>\n<pre><code class=\"hljs coffeescript\"> tcp_tw_recycle (Boolean; default: disabled; since Linux <span class=\"hljs-number\">2.4<\/span>)\r\n              Enable fast recycling <span class=\"hljs-keyword\">of<\/span> TIME_WAIT sockets.  Enabling <span class=\"hljs-keyword\">this<\/span> option <span class=\"hljs-keyword\">is<\/span> <span class=\"hljs-keyword\">not<\/span> recommended since <span class=\"hljs-keyword\">this<\/span> causes problems <span class=\"hljs-keyword\">when<\/span> working with NAT (Network Address\r\n              Translation).<\/code><\/pre>\n<p>\u5f00\u542ftcp_tw_recycle\u4f1a\u542f\u7528tcp time_wait\u7684\u5feb\u901f\u56de\u6536\uff0c\u8fd9\u4e2a\u53c2\u6570\u4e0d\u5efa\u8bae\u5728NAT\u73af\u5883\u4e2d\u542f\u7528\uff0c\u5b83\u4f1a\u5f15\u8d77\u76f8\u5173\u95ee\u9898\u3002<\/p>\n<p>tcp_tw_recycle\u662f\u4f9d\u8d56tcp_timestamps\u53c2\u6570\u7684\uff0c\u5728\u4e00\u822c\u7f51\u7edc\u73af\u5883\u4e2d\uff0c\u53ef\u80fd\u4e0d\u4f1a\u6709\u95ee\u9898\uff0c\u4f46\u662f\u5728NAT\u73af\u5883\u4e2d\uff0c\u95ee\u9898\u5c31\u6765\u4e86\u3002\u6bd4\u5982\u6211\u9047\u5230\u7684\u8fd9\u4e2a\u60c5\u51b5\uff0c\u529e\u516c\u5ba4\u7684\u5916\u7f51\u5730\u5740\u53ea\u6709\u4e00\u4e2a\uff0c\u6240\u6709\u4eba\u8bbf\u95ee\u540e\u53f0\u90fd\u4f1a\u901a\u8fc7\u8def\u7531\u5668\u505aSNAT\u5c06\u5185\u7f51\u5730\u5740\u6620\u5c04\u4e3a\u516c\u7f51IP\uff0c\u7531\u4e8e\u670d\u52a1\u7aef\u548c\u5ba2\u6237\u7aef\u90fd\u542f\u7528\u4e86tcp_timestamps\uff0c\u56e0\u6b64TCP\u5934\u90e8\u4e2d\u589e\u52a0\u65f6\u95f4\u6233\u4fe1\u606f\uff0c\u800c\u5728\u670d\u52a1\u5668\u770b\u6765\uff0c\u540c\u4e00\u5ba2\u6237\u7aef\u7684\u65f6\u95f4\u6233\u5fc5\u7136\u662f\u7ebf\u6027\u589e\u957f\u7684\uff0c\u4f46\u662f\uff0c\u7531\u4e8e\u6211\u7684\u5ba2\u6237\u7aef\u7f51\u7edc\u73af\u5883\u662fNAT\uff0c\u56e0\u6b64\u6bcf\u53f0\u4e3b\u673a\u7684\u65f6\u95f4\u6233\u90fd\u662f\u6709\u5dee\u5f02\u7684\uff0c\u5728\u542f\u7528tcp_tw_recycle\u540e\uff0c\u4e00\u65e6\u6709\u5ba2\u6237\u7aef\u65ad\u5f00\u8fde\u63a5\uff0c\u670d\u52a1\u5668\u53ef\u80fd\u5c31\u4f1a\u4e22\u5f03\u90a3\u4e9b\u65f6\u95f4\u6233\u8f83\u5c0f\u7684\u5ba2\u6237\u7aef\u7684SYN\u5305\uff0c\u8fd9\u4e5f\u5c31\u5bfc\u81f4\u4e86\u7f51\u7ad9\u8bbf\u95ee\u6781\u4e0d\u7a33\u5b9a\u3002<\/p>\n<p>\u4e3b\u673aA SIP:P1 (\u65f6\u95f4\u6233T0) &#8212;&gt; Server \u4e3b\u673aA\u65ad\u5f00\u540e<br \/>\n\u4e3b\u673aB SIP:P1 (\u65f6\u95f4\u6233T2) T2 &lt; T0 &#8212;&gt; Server \u4e22\u5f03<\/p>\n<p><audio style=\"display: none;\" controls=\"controls\"><\/audio><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e00\uff0c\u6545\u969c\u63cf\u8ff0\uff1a \u4ece\u6628\u5929\u5f00\u59cb\uff0c\u5728\u503c\u73ed\u7fa4\u4e2d\u9646\u7eed\u503c\u73ed\u4eba\u5458\u53cd\u6620\u7cfb\u7edf\u540e\u53f0\u5b58\u5728\u5361\u987f\u95ee\u9898\uff0c\u5982\u4e0b\u56fe\uff1a \u800c\u4e14\u5728\u5361\u987f\u7684\u540c\u65f6\u767b\u9646\u670d\u52a1 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-3707","post","type-post","status-publish","format-standard","hentry","category-day"],"_links":{"self":[{"href":"http:\/\/switch.linesno.com\/index.php?rest_route=\/wp\/v2\/posts\/3707","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/switch.linesno.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/switch.linesno.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/switch.linesno.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/switch.linesno.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3707"}],"version-history":[{"count":1,"href":"http:\/\/switch.linesno.com\/index.php?rest_route=\/wp\/v2\/posts\/3707\/revisions"}],"predecessor-version":[{"id":3711,"href":"http:\/\/switch.linesno.com\/index.php?rest_route=\/wp\/v2\/posts\/3707\/revisions\/3711"}],"wp:attachment":[{"href":"http:\/\/switch.linesno.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3707"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/switch.linesno.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3707"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/switch.linesno.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3707"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}