{"id":2065,"date":"2017-04-11T15:16:15","date_gmt":"2017-04-11T07:16:15","guid":{"rendered":"http:\/\/cn.hostease.com\/xueyuan\/?p=2065"},"modified":"2025-01-13T19:05:28","modified_gmt":"2025-01-13T11:05:28","slug":"centos%e5%ae%89%e5%85%a8%e4%b9%8bsyn%e6%94%bb%e5%87%bb%e5%8e%9f%e7%90%86%e5%8f%8a%e5%a4%84%e7%90%86","status":"publish","type":"post","link":"https:\/\/cn.hostease.com\/xueyuan\/jishu\/centos%e5%ae%89%e5%85%a8%e4%b9%8bsyn%e6%94%bb%e5%87%bb%e5%8e%9f%e7%90%86%e5%8f%8a%e5%a4%84%e7%90%86\/","title":{"rendered":"CentOS\u5b89\u5168\u4e4bSYN\u653b\u51fb\u539f\u7406\u53ca\u5904\u7406"},"content":{"rendered":"\n

TCP\u81ea\u4ece1974\u5e74\u88ab\u53d1\u660e\u51fa\u6765\u4e4b\u540e\uff0c\u5386\u7ecf30\u591a\u5e74\u53d1\u5c55\uff0c\u76ee\u524d\u6210\u4e3a\u6700\u91cd\u8981\u7684\u4e92\u8054\u7f51\u57fa\u7840\u534f\u8bae\uff0c\u4f46TCP\u534f\u8bae\u4e2d\u4e5f\u5b58\u5728\u4e00\u4e9b\u7f3a\u9677\u3002<\/p>\n\n\n\n

SYN\u653b\u51fb\u5c31\u662f\u5229\u7528TCP\u534f\u8bae\u7684\u7f3a\u9677\uff0c\u6765\u5bfc\u81f4\u7cfb\u7edf\u670d\u52a1\u505c\u6b62\u6b63\u5e38\u7684\u54cd\u5e94\u3002<\/p>\n\n\n\n

SYN\u653b\u51fb\u539f\u7406<\/strong><\/p>\n\n\n\n

\n\n\n\n

 <\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

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

TCP\u5728\u4f20\u9012\u6570\u636e\u524d\u9700\u8981\u7ecf\u8fc7\u4e09\u6b21\u63e1\u624b\uff0cSYN\u653b\u51fb\u7684\u539f\u7406\u5c31\u662f\u5411\u670d\u52a1\u5668\u53d1\u9001SYN\u6570\u636e\u5305\uff0c\u5e76\u4f2a\u9020\u6e90IP\u5730\u5740\u3002<\/p>\n\n\n\n

\u670d\u52a1\u5668\u5728\u6536\u5230SYN\u6570\u636e\u5305\u65f6\uff0c\u4f1a\u5c06\u8fde\u63a5\u52a0\u5165backlog\u961f\u5217\uff0c\u5e76\u5411\u6e90IP\u53d1\u9001SYN-ACK\u6570\u636e\u5305\uff0c\u5e76\u7b49\u5f85ACK\u6570\u636e\u5305\uff0c\u4ee5\u5b8c\u6210\u4e09\u6b21\u63e1\u624b\u5efa\u7acb\u8fde\u63a5\u3002<\/p>\n\n\n\n

\u7531\u4e8e\u6e90IP\u5730\u5740\u662f\u4f2a\u9020\u7684\u4e0d\u5b58\u5728\u4e3b\u673aIP\uff0c\u6240\u4ee5\u670d\u52a1\u5668\u65e0\u6cd5\u6536\u5230ACK\u6570\u636e\u5305\uff0c\u5e76\u4f1a\u4e0d\u65ad\u91cd\u53d1\uff0c\u540c\u65f6backlog\u961f\u5217\u88ab\u4e0d\u65ad\u88ab\u653b\u51fb\u7684SYN\u8fde\u63a5\u5360\u6ee1\uff0c\u5bfc\u81f4\u65e0\u6cd5\u5904\u7406\u6b63\u5e38\u7684\u8fde\u63a5\u3002<\/p>\n\n\n\n

SYN\u653b\u51fb\u5904\u7406<\/strong><\/p>\n\n\n\n

\n\n\n\n

\u9488\u5bf9SYN\u653b\u51fb\u7684\u51e0\u4e2a\u73af\u8282\uff0c\u63d0\u51fa\u76f8\u5e94\u7684\u5904\u7406\u65b9\u6cd5\uff1a<\/p>\n\n\n\n

\u65b9\u5f0f1\uff1a\u51cf\u5c11SYN-ACK\u6570\u636e\u5305\u7684\u91cd\u53d1\u6b21\u6570\uff08\u9ed8\u8ba4\u662f5\u6b21\uff09\uff1a<\/p>\n\n\n\n

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\n\n\n\n
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sysctl -w net.ipv4.tcp_synack_retries=3 <\/code><\/div>\n
sysctl -w net.ipv4.tcp_syn_retries=3 <\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

\u65b9\u5f0f2\uff1a\u4f7f\u7528SYN Cookie\u6280\u672f\uff1a<\/p>\n\n\n\n

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\n\n\n\n
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sysctl -w net.ipv4.tcp_syncookies=1 <\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

\u65b9\u5f0f3\uff1a\u589e\u52a0backlog\u961f\u5217\uff08\u9ed8\u8ba4\u662f1024\uff09\uff1a<\/p>\n\n\n\n

\n
\n
\n\n\n\n
\n
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sysctl -w net.ipv4.tcp_max_syn_backlog=2048 <\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

\u65b9\u5f0f4\uff1a\u9650\u5236SYN\u5e76\u53d1\u6570\uff1a<\/p>\n\n\n\n

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\n
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iptables -A INPUT -p tcp --syn -m limit --limit 1\/s -j ACCEPT --limit 1\/s<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

TCP\u81ea\u4ece1974\u5e74\u88ab\u53d1\u660e\u51fa\u6765\u4e4b\u540e\uff0c\u5386\u7ecf30\u591a\u5e74\u53d1\u5c55\uff0c\u76ee\u524d\u6210\u4e3a\u6700\u91cd\u8981\u7684\u4e92\u8054\u7f51\u57fa\u7840\u534f\u8bae\uff0c\u4f46TCP\u534f\u8bae\u4e2d\u4e5f\u5b58\u5728\u4e00\u4e9b … \u9605\u8bfb\u66f4\u591a<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[49,5],"tags":[38,623],"class_list":["post-2065","post","type-post","status-publish","format-standard","hentry","category-linux","category-jishu","tag-linux","tag-syn"],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack-related-posts":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/2065","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/comments?post=2065"}],"version-history":[{"count":2,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/2065\/revisions"}],"predecessor-version":[{"id":9306,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/2065\/revisions\/9306"}],"wp:attachment":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/media?parent=2065"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/categories?post=2065"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/tags?post=2065"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}