{"id":1308,"date":"2023-08-25T13:57:12","date_gmt":"2023-08-25T05:57:12","guid":{"rendered":"https:\/\/www.shuran.cn\/?p=1308"},"modified":"2023-08-25T13:57:12","modified_gmt":"2023-08-25T05:57:12","slug":"tcp%e5%86%85%e6%a0%b8%e5%8f%82%e6%95%b0","status":"publish","type":"post","link":"https:\/\/www.shuran.cn\/?p=1308","title":{"rendered":"TCP\u5185\u6838\u53c2\u6570"},"content":{"rendered":"\n

tcp_max_syn_backlog<\/strong>
\u2014\u2014\u2014\u2014\u2014\u2014-
\u7aef\u53e3\u6700\u5927 backlog \u5185\u6838\u9650\u5236\u3002\u6b64\u53c2\u6570\u9650\u5236 \u670d\u52a1\u7aef\u5e94\u7528\u7a0b\u5e8f \u53ef\u4ee5\u8bbe\u7f6e\u7684\u7aef\u53e3\u6700\u5927 backlog \u503c (\u5bf9\u5e94\u4e8e\u7aef\u53e3\u7684 syn_backlog \u548c backlog \u961f\u5217\u957f\u5ea6)\u3002\u52a8\u673a\u662f\u5728\u5185\u5b58\u6709\u9650\u7684\u670d\u52a1\u5668\u4e0a\u9650\u5236\/\u907f\u514d\u5e94\u7528\u7a0b\u5e8f\u914d\u7f6e\u8d85\u5927 backlog \u503c\u800c\u8017\u5c3d\u5185\u6838\u5185\u5b58\u3002\u5982\u679c\u5e94\u7528\u7a0b\u5e8f\u8bbe\u7f6e backlog \u5927\u4e8e\u6b64\u503c\uff0c\u64cd\u4f5c\u7cfb\u7edf\u5c06\u81ea\u52a8\u5c06\u4e4b\u9650\u5236\u5230\u6b64\u503c\u3002<\/p>\n\n\n\n

tcp_abort_on_overflow<\/strong>
\u2014\u2014\u2014\u2014\u2014\u2014\u2014
\u5f53 tcp \u5efa\u7acb\u8fde\u63a5\u7684 3 \u8def\u63e1\u624b\u5b8c\u6210\u540e\uff0c\u5c06\u8fde\u63a5\u7f6e\u5165 ESTABLISHED \u72b6\u6001\u5e76\u4ea4\u4ed8\u7ed9\u5e94\u7528\u7a0b\u5e8f\u7684 backlog \u961f\u5217\u65f6\uff0c\u4f1a\u68c0\u67e5 backlog \u961f\u5217\u662f\u5426\u5df2\u6ee1\u3002\u82e5\u5df2\u6ee1\uff0c\u901a\u5e38\u884c\u4e3a\u662f\u5c06\u8fde\u63a5\u8fd8\u539f\u81f3 SYN_ACK \u72b6\u6001\uff0c\u4ee5\u9020\u6210 3 \u8def\u63e1\u624b\u6700\u540e\u7684 ACK \u5305\u610f\u5916\u4e22\u5931\u5047\u8c61 \u2014\u2014 \u8fd9\u6837\u5728\u5ba2\u6237\u7aef\u7b49\u5f85\u8d85\u65f6\u540e\u53ef\u91cd\u53d1 ACK \u2014\u2014 \u4ee5\u518d\u6b21\u5c1d\u8bd5\u8fdb\u5165 ESTABLISHED \u72b6\u6001 \u2014\u2014 \u4f5c\u4e3a\u4e00\u79cd\u4fee\u590d\/\u91cd\u8bd5\u673a\u5236\u3002\u5982\u679c\u542f\u7528 tcp_abort_on_overflow \u5219\u5728\u68c0\u67e5\u5230 backlog \u961f\u5217\u5df2\u6ee1\u65f6\uff0c\u76f4\u63a5\u53d1 RST \u5305\u7ed9\u5ba2\u6237\u7aef\u7ec8\u6b62\u6b64\u8fde\u63a5 \u2014\u2014 \u6b64\u65f6\u5ba2\u6237\u7aef\u7a0b\u5e8f\u4f1a\u6536\u5230 104 Connection reset by peer \u9519\u8bef\u3002

\u8b66\u544a\uff1a<\/strong>\u542f\u7528\u6b64\u9009\u9879\u53ef\u80fd\u5bfc\u81f4\u9ad8\u5cf0\u671f\u7528\u6237\u8bbf\u95ee\u4f53\u9a8c\u5230 104: Connection reset by peer \u6216 \u767d\u5c4f \u9519\u8bef(\u89c6\u6d4f\u89c8\u5668\u800c\u5b9a)\u3002\u5728\u8003\u8651\u542f\u7528\u6b64\u9009\u9879\u524d\u5e94\u5148\u8bbe\u6cd5\u4f18\u5316\u63d0\u9ad8 \u670d\u52a1\u7aef\u5e94\u7528\u7a0b\u5e8f \u7684\u6027\u80fd\uff0c\u4f7f\u4e4b\u80fd\u66f4\u5feb \u63a5\u7ba1\u3001\u5904\u7406 \u8fde\u63a5\u3002<\/p>\n\n\n\n

tcp_syncookies<\/strong>
\u2014\u2014\u2014\u2014\u2013
\u5728 tcp \u5efa\u7acb\u8fde\u63a5\u7684 3 \u8def\u63e1\u624b\u8fc7\u7a0b\u4e2d\uff0c\u5f53\u670d\u52a1\u7aef\u6536\u5230\u6700\u521d\u7684 SYN \u8bf7\u6c42\u65f6\uff0c\u4f1a\u68c0\u67e5\u5e94\u7528\u7a0b\u5e8f\u7684 syn_backlog \u961f\u5217\u662f\u5426\u5df2\u6ee1\u3002\u82e5\u5df2\u6ee1\uff0c\u901a\u5e38\u884c\u4e3a\u662f\u4e22\u5f03\u6b64 SYN \u5305\u3002\u82e5\u672a\u6ee1\uff0c\u4f1a\u518d\u68c0\u67e5\u5e94\u7528\u7a0b\u5e8f\u7684 backlog \u961f\u5217\u662f\u5426\u5df2\u6ee1\u3002\u82e5\u5df2\u6ee1\u5e76\u4e14\u7cfb\u7edf\u6839\u636e\u5386\u53f2\u8bb0\u5f55\u5224\u65ad\u8be5\u5e94\u7528\u7a0b\u5e8f\u4e0d\u4f1a\u8f83\u5feb\u6d88\u8017\u8fde\u63a5\u65f6\uff0c\u5219\u4e22\u5f03\u6b64 SYN \u5305\u3002\u5982\u679c\u542f\u7528 tcp_syncookies \u5219\u5728\u68c0\u67e5\u5230 syn_backlog \u961f\u5217\u5df2\u6ee1\u65f6\uff0c\u4e0d\u4e22\u5f03\u8be5 SYN \u5305\uff0c\u800c\u6539\u7528 syncookie \u6280\u672f\u8fdb\u884c 3 \u8def\u63e1\u624b\u3002<\/p>\n\n\n\n

\u8b66\u544a\uff1a<\/strong>\u4f7f\u7528 syncookie \u8fdb\u884c\u63e1\u624b\u65f6\uff0c\u56e0\u4e3a\u8be5\u6280\u672f\u632a\u7528\u4e86 tcp_options \u5b57\u6bb5\u7a7a\u95f4\uff0c\u4f1a\u5f3a\u5236\u5173\u95ed tcp \u9ad8\u7ea7\u6d41\u63a7\u6280\u672f\u800c\u9000\u5316\u6210\u539f\u59cb tcp \u6a21\u5f0f\u3002\u6b64\u6a21\u5f0f\u4f1a\u5bfc\u81f4 \u5c01\u5305 \u4e22\u5931\u65f6 \u5bf9\u7aef \u8981\u7b49\u5f85 MSL \u65f6\u95f4\u6765\u53d1\u73b0\u4e22\u5305\u4e8b\u4ef6\u5e76\u91cd\u8bd5\uff0c\u4ee5\u53ca\u5173\u95ed\u8fde\u63a5\u65f6 TIME_WAIT \u72b6\u6001\u4fdd\u6301 2MSL \u65f6\u95f4\u3002\u8be5\u6280\u672f\u5e94\u8be5\u4ec5\u7528\u4e8e\u4fdd\u62a4 syn_flood \u653b\u51fb\u3002\u5982\u679c\u5728\u6b63\u5e38\u670d\u52a1\u5668\u73af\u5883\u4e2d\u670d\u52a1\u5668\u8d1f\u8f7d\u8f83\u91cd\u5bfc\u81f4 syn_backlog \u548c backlog \u961f\u5217\u6ee1\u65f6\uff0c\u5e94\u4f18\u5316 \u670d\u52a1\u7aef\u5e94\u7528\u7a0b\u5e8f \u7684 \u8d1f\u8f7d\u80fd\u529b\uff0c\u52a0\u5927\u5e94\u7528\u7a0b\u5e8f backlog \u503c\u3002\u4e0d\u8fc7\uff0c\u6240\u5e78\u8be5\u53c2\u6570\u662f\u81ea\u52a8\u503c\uff0c\u4ec5\u5728 syn_backlog \u961f\u5217\u6ee1\u65f6\u624d\u4f1a\u89e6\u53d1 (\u5728\u961f\u5217\u6062\u590d\u53ef\u7528\u65f6\u6b64\u884c\u4e3a\u5173\u95ed)\u3002<\/p>\n\n\n\n

NOTE 1:<\/strong>
\u670d\u52a1\u7aef\u5e94\u7528\u7a0b\u5e8f\u8bbe\u7f6e\u7aef\u53e3 backlog \u503c\uff0c\u5185\u6838\u7406\u8bba\u4e0a\u5c06\u5141\u8bb8\u8be5\u7aef\u53e3\u6700\u5927\u540c\u65f6\u63a5\u6536 2*backlog \u4e2a\u5e76\u53d1\u8fde\u63a5\u201d\u8bf7\u6c42\u201d(\u4e0d\u542b\u5df2\u88ab\u5e94\u7528\u7a0b\u5e8f\u63a5\u7ba1\u7684\u8fde\u63a5) \u2014\u2014 \u5206\u522b\u5b58\u653e\u5728 syn_backlog \u548c backlog \u961f\u5217 \u2014\u2014 \u6bcf\u4e2a\u961f\u5217\u7684\u957f\u5ea6\u4e3a backlog \u503c\u3002syn_backlog \u961f\u5217\u5b58\u50a8 SYN_ACK \u72b6\u6001\u7684\u8fde\u63a5\uff0cbacklog \u5219\u5b58\u50a8 ESTABLISHED \u72b6\u6001\u4f46\u5c1a\u672a\u88ab\u5e94\u7528\u7a0b\u5e8f\u63a5\u7ba1\u7684\u8fde\u63a5\u3002<\/p>\n\n\n\n

NOTE 2:<\/strong>
syn_backlog \u961f\u5217\u5b9e\u9645\u4e0a\u662f\u4e2a hash \u8868\uff0c\u5e76\u4e14 hash \u8868\u5927\u5c0f\u4e3a 2 \u7684\u6b21\u65b9\u3002\u6240\u4ee5\u5b9e\u9645 syn_backlog \u7684\u961f\u5217\u957f\u5ea6\u8981 \u7565\u5927\u4e8e \u5e94\u7528\u7a0b\u5e8f\u8bbe\u7f6e\u7684 backlog \u503c \u2014\u2014 \u53d6\u5bf9\u5e94 2 \u7684\u6b21\u65b9\u503c\u3002<\/p>\n\n\n\n

NOTE 3:<\/strong>
\u5f53 backlog \u503c\u8f83\u5c0f\uff0c\u800c\u9ad8\u5cf0\u671f\u5e76\u53d1\u8fde\u63a5\u8bf7\u6c42\u8d85\u9ad8\u65f6\uff0ctcp \u5efa\u7acb\u8fde\u63a5\u7684 \u4e09\u8def\u63e1\u624b \u7f51\u7edc\u65f6\u5ef6\u5c06\u6210\u4e3a\u74f6\u9888 \u2014\u2014 \u5e76\u53d1\u8fde\u63a5\u8d85\u9ad8\u65f6\uff0csyn_backlog \u961f\u5217\u5c06\u88ab\u5145\u6ee1\u800c\u5bfc\u81f4 `can\u2019t connect` \u9519\u8bef\u3002\u6b64\u65f6\uff0c\u518d\u63d0\u9ad8\u670d\u52a1\u7aef\u5e94\u7528\u7a0b\u5e8f\u7684\u541e\u5410\u80fd\u529b\u5df2\u4e0d\u8d77\u4f5c\u7528\uff0c\u56e0\u4e3a\u8fde\u63a5\u5c1a\u672a\u5efa\u7acb\uff0c\u670d\u52a1\u7aef\u5e94\u7528\u7a0b\u5e8f\u5e76\u4e0d\u80fd\u63a5\u7ba1\u548c\u5904\u7406\u8fd9\u4e9b\u8fde\u63a5 \u2014\u2014 \u800c\u662f\u9700\u8981\u52a0\u5927 backlog \u503c (syn_backlog \u961f\u5217\u957f\u5ea6) \u6765\u7f13\u89e3\u6b64\u95ee\u9898\u3002<\/p>\n\n\n\n

NOTE 4:<\/strong>
\u542f\u7528 syncookie \u867d\u7136\u4e5f\u53ef\u4ee5\u89e3\u51b3\u8d85\u9ad8\u5e76\u53d1\u65f6\u7684 `can\u2019t connect` \u95ee\u9898\uff0c\u4f46\u4f1a\u5bfc\u81f4 TIME_WAIT \u72b6\u6001 fallback \u4e3a\u4fdd\u6301 2MSL \u65f6\u95f4\uff0c\u9ad8\u5cf0\u671f\u65f6\u4f1a\u5bfc\u81f4\u5ba2\u6237\u7aef\u65e0\u53ef\u590d\u7528\u8fde\u63a5\u800c\u65e0\u6cd5\u8fde\u63a5\u670d\u52a1\u5668 (tcp \u8fde\u63a5\u590d\u7528\u662f\u57fa\u4e8e <src_ip, src_port, dst_ip, dst_port> \u56db\u5143\u7ec4\u503c\u5fc5\u987b\u4e0d\u76f8\u540c\uff0c\u5c31\u8bbf\u95ee\u540c\u4e00\u4e2a\u76ee\u6807\u670d\u52a1\u5668\u800c\u8a00\uff0c<src_ip, dst_ip, dst_port> \u4e09\u5143\u7ec4\u503c\u4e0d\u53d8\uff0c\u6240\u4ee5\u6b64\u65f6\u53ef\u7528\u7684\u8fde\u63a5\u6570\u9650\u5236\u4e3a\u4ec5 src_port \u6240\u5141\u8bb8\u6570\u76ee\uff0c\u8fd9\u91cc\u5904\u4e8e TIME_WAIT \u72b6\u6001\u7684\u76f8\u540c src_port \u8fde\u63a5\u4e0d\u53ef\u590d\u7528\u3002Linux \u7cfb\u7edf\u751a\u81f3\u66f4\u4e25\u683c\uff0c\u53ea\u4f7f\u7528\u4e86 <src_ip, src_port, dst_ip> \u4e09\u5143\u7ec4\u2026)\u3002\u6545\u4e0d\u5efa\u8bae\u4f9d\u8d56 syncookie\u3002<\/p>\n\n\n\n

backlog \u00a0 \u7528\u4e8e\u5728TCP\u5c42\u63a5\u6536\u94fe\u63a5\u7684\u7f13\u51b2\u6c60\u7684\u6700\u5927\u4e2a\u6570\uff0c\u8fd9\u4e2a\u4e2a\u6570\u53ef\u5728\u5e94\u7528\u5c42\u4e2d\u7684listen\u51fd\u6570\u91cc\u8bbe\u7f6e\uff0c\u5f53\u5ba2\u6237\u94fe\u63a5\u8bf7\u6c42\u5927\u4e8e\u8fd9\u4e2a\u4e2a\u6570(\u7f13\u51b2\u6c60\u6ee1\uff09\uff0c\u5176\u5b83\u7684\u672a\u8fdb\u5165\u94fe\u63a5\u7f13\u51b2\u6c60\u7684\u5ba2\u6237\u7aef\u5728tcp\u5c42\u4e0atcp\u6a21\u5757\u4f1a\u81ea\u52a8\u91cd\u65b0\u94fe\u63a5\uff0c\u76f4\u5230\u8d85\u65f6\uff08\u5927\u7ea657\u79d2\u540e\uff09<\/p>\n\n\n\n

Linux\u4e2d\u67e5\u770bsocket\u72b6\u6001\uff1acat \/proc\/net\/sockstat<\/p>\n\n\n\n

cat \/proc\/net\/sockstat
sockets:<\/code> used 137 <\/code>
TCP: inuse 49 orphan 0 tw 3272 alloc 52 mem 46 <\/code>
UDP: inuse 1 mem 0 <\/code>
RAW: inuse 0 <\/code>
FRAG: inuse 0 memory 0<\/code><\/p>\n\n\n\n

\u8bf4\u660e\uff1a
sockets: used\uff1a\u5df2\u4f7f\u7528\u7684\u6240\u6709\u534f\u8bae\u5957\u63a5\u5b57\u603b\u91cf
TCP: inuse\uff1a\u6b63\u5728\u4f7f\u7528\uff08\u6b63\u5728\u4fa6\u542c\uff09\u7684TCP\u5957\u63a5\u5b57\u6570\u91cf\u3002\u5176\u503c\u2264 netstat \u2013lnt | grep ^tcp | wc \u2013l
TCP: orphan\uff1a\u65e0\u4e3b\uff08\u4e0d\u5c5e\u4e8e\u4efb\u4f55\u8fdb\u7a0b\uff09\u7684TCP\u8fde\u63a5\u6570\uff08\u65e0\u7528\u3001\u5f85\u9500\u6bc1\u7684TCP socket\u6570\uff09
TCP:\u00a0tw\uff1a\u7b49\u5f85\u5173\u95ed\u7684TCP\u8fde\u63a5\u6570\u3002\u5176\u503c\u7b49\u4e8enetstat \u2013ant | grep TIME_WAIT | wc \u2013l
TCP\uff1aalloc(allocated)\uff1a\u5df2\u5206\u914d\uff08\u5df2\u5efa\u7acb\u3001\u5df2\u7533\u8bf7\u5230sk_buff\uff09\u7684TCP\u5957\u63a5\u5b57\u6570\u91cf\u3002\u5176\u503c\u7b49\u4e8enetstat \u2013ant | grep ^tcp | wc \u2013l
TCP\uff1amem\uff1a\u5957\u63a5\u5b57\u7f13\u51b2\u533a\u4f7f\u7528\u91cf\uff08\u5355\u4f4d\u4e0d\u8be6\u3002\u7528scp\u5b9e\u6d4b\uff0c\u901f\u5ea6\u57284803.9kB\/s\u65f6\uff1a\u5176\u503c=11\uff0cnetstat \u2013ant \u4e2d\u76f8\u5e94\u768422\u7aef\u53e3\u7684Recv-Q\uff1d0\uff0cSend-Q\u2248400\uff09
UDP\uff1ainuse\uff1a\u6b63\u5728\u4f7f\u7528\u7684UDP\u5957\u63a5\u5b57\u6570\u91cf
RAW\uff1a
FRAG\uff1a\u4f7f\u7528\u7684IP\u6bb5\u6570\u91cf<\/p>\n","protected":false},"excerpt":{"rendered":"

tcp_max_syn_backlog\u2014\u2014\u2014\u2014\u2014\u2014-\u7aef\u53e3\u6700\u5927 backlog \u5185\u6838\u9650\u5236\u3002\u6b64\u53c2\u6570\u9650\u5236 \u670d\u52a1\u7aef\u5e94\u7528\u2026 Read More »<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-1308","post","type-post","status-publish","format-standard","hentry","category-os"],"_links":{"self":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts\/1308","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1308"}],"version-history":[{"count":1,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts\/1308\/revisions"}],"predecessor-version":[{"id":1309,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=\/wp\/v2\/posts\/1308\/revisions\/1309"}],"wp:attachment":[{"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1308"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1308"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuran.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1308"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}