{"id":699,"date":"2016-10-23T13:56:31","date_gmt":"2016-10-23T05:56:31","guid":{"rendered":"http:\/\/www.ipcpu.com\/?p=699"},"modified":"2016-10-23T13:56:31","modified_gmt":"2016-10-23T05:56:31","slug":"tcp-handshake-backlog","status":"publish","type":"post","link":"https:\/\/c.ipcpu.com\/2016\/10\/tcp-handshake-backlog\/","title":{"rendered":"TCP\u4e09\u6b21\u63e1\u624b-backlog\u961f\u5217\u95ee\u9898"},"content":{"rendered":"

TCP\u4e09\u6b21\u63e1\u624b-backlog\u961f\u5217\u95ee\u9898.md<\/p>\n

\u6982\u8ff0<\/h2>\n

\u4e4b\u524d\u6709\u540c\u4e8b\u505a\u538b\u529b\u6d4b\u8bd5\u65f6\uff0c\u53d1\u73b0\u65e0\u8bba\u5982\u4f55\u90fd\u65e0\u6cd5\u7a81\u7834128\u5e76\u53d1\u7684\u95ee\u9898\uff0c\u7ecf\u6392\u67e5\u53d1\u73b0\u8be5\u670d\u52a1\u5668ACCEPT QUEUE\u961f\u5217\u90fd\u4e3a128\uff0c\u9650\u5236\u4e86\u7f51\u7edc\u7684\u5e76\u53d1\u3002<\/p>\n

TCP\u4e09\u6b21\u63e1\u624b<\/h2>\n

<\/p>\n

Linux\u5185\u6838\u534f\u8bae\u6808\u4e3a\u4e00\u4e2aTCP\u8fde\u63a5\u7ba1\u7406\u4f7f\u7528\u4e24\u4e2a\u961f\u5217\uff0c\u4e00\u4e2a\u662f\u534a\u94fe\u63a5\u961f\u5217SYN QUEUE\uff08\u7528\u6765\u4fdd\u5b58\u5904\u4e8eSYN_SENT\u548cSYN_RECV\u72b6\u6001\u7684\u8bf7\u6c42\uff09\uff0c\u4e00\u4e2a\u662fACCEPT\u961f\u5217 ACCEPT QUEUE\uff08\u7528\u6765\u4fdd\u5b58\u5904\u4e8eestablished\u72b6\u6001\uff0c\u4f46\u662f\u5e94\u7528\u5c42\u6ca1\u6709\u8c03\u7528accept\u53d6\u8d70\u7684\u8bf7\u6c42\uff09\u3002<\/p>\n

    \n
  1. \n

    \u5f53client \u5efa\u7acb\u8fde\u63a5\u65f6\u53d1\u9001SYN\u5305\u5230server\u7aef\uff0cserver\u6536\u5230\u4e4b\u540e\u5982\u679cSYN QUEUE\u961f\u5217\u5df2\u6ee1\uff0c\u76f4\u63a5\u4e22\u5f03\u4e0d\u56deACK\u3002\u5ba2\u6237\u7aef\u8d85\u65f6\u540e\u7ecf\u8fc73\u79d2\u30019\u79d2\u2026\u7684\u95f4\u9694\u65f6\u5019\u4e0d\u65ad\u91cd\u53d1SYN\u5305\u3002<\/p>\n<\/li>\n

  2. \n

    \u5f53server\u7684SYN QUEUE\u6ca1\u6709\u6ee1\u65f6\uff0cserver\u4f1a\u56de\u590dSYN+ACK\u7ed9client\uff0c\u5982\u679cclient\u6536\u5230\u8bf7\u6c42\uff0c\u5219\u5c06\u72b6\u6001\u4fee\u6539\u4e3aESTABLISHED\uff0c\u5e76\u53d1\u9001ACK\u7ed9server\u3002<\/p>\n<\/li>\n

  3. \n

    server\u6536\u5230ACK\uff0c\u5c06\u72b6\u6001\u4fee\u6539\u4e3aESTABLISHED\uff0c\u5e76\u628a\u8be5\u8bf7\u6c42\u4eceSYN QUEUE\u4e2d\u653e\u5230ACCEPT QUEUE\u3002<\/p>\n<\/li>\n<\/ol>\n

    SYN QUEUE\u961f\u5217<\/h2>\n

    \u7528\u4e8e\u4fdd\u5b58\u534a\u8fde\u63a5\u72b6\u6001\u7684\u8bf7\u6c42\uff0c\u5176\u5927\u5c0f\u901a\u8fc7\/proc\/sys\/net\/ipv4\/tcp_max_syn_backlog\u6307\u5b9a\u3002<\/p>\n

    \n

    SYN QUEUE\u961f\u5217\u957f\u5ea6\uff1atcp_max_syn_backlog<\/p>\n<\/blockquote>\n

    \u901a\u8fc7netstat -s\u53ef\u4ee5\u67e5\u770b\u88abSYN QUEUE\u961f\u5217\u4e22\u5f03\u7684\u6570\u636e<\/p>\n

    1. [<\/span>root@nginx2<\/span>.<\/span>proxy<\/span>.<\/span>qyer<\/span>.<\/span>idc <\/span>~]#<\/span>netstat <\/span>-<\/span>s <\/span>|<\/span> grep <\/span>\"SYNs to LISTEN sockets ignored\"<\/span><\/code><\/li>
    2.     <\/span>35552<\/span> <\/span>SYNs<\/span> to LISTEN sockets ignored<\/span><\/code><\/li>
    3. [<\/span>root@nginx2<\/span>.<\/span>proxy<\/span>.<\/span>qyer<\/span>.<\/span>idc <\/span>~]#<\/span><\/code><\/li><\/ol><\/pre>\n
      ACCEPT QUEUE\u961f\u5217<\/h2>\n
      \u7528\u4e8e\u4fdd\u5b58\u5168\u8fde\u63a5\u72b6\u6001\u7684\u8bf7\u6c42\uff0c\u5176\u5927\u5c0f\u901a\u8fc7\/proc\/sys\/net\/core\/somaxconn\uff08\u9ed8\u8ba4\u662f128\uff09\u6307\u5b9a\uff0c\u5728\u4f7f\u7528listen\u51fd\u6570\u65f6\uff0c\u5185\u6838\u4f1a\u6839\u636e\u4f20\u5165\u7684backlog\u53c2\u6570\u4e0e\u7cfb\u7edf\u53c2\u6570somaxconn\u6bd4\u8f83\uff0c\u53d6\u4e8c\u8005\u7684\u8f83\u5c0f\u503c\u3002<\/p>\n
      \n
      ACCEPT QUEUE\u961f\u5217\u957f\u5ea6\uff1amin(backlog, somaxconn)<\/p>\n<\/blockquote>\n
      \u5982\u679caccpet queue\u961f\u5217\u6ee1\u4e86\uff0cserver\u5c06\u5982\u4f55\u5904\u7406\u5462\uff1f\u53d6\u51b3\u4e8e\u4e00\u4e2a\u53c2\u6570tcp_aborton_overflow\uff0c\u5f53tcp_aborton_overflow\u53c2\u6570\u4e3a1\uff0c\u4f1a\u53d1\u9001 RST\uff1b\u5982\u679c\u4e3a0(\u9ed8\u8ba4\u503c)\uff0c\u5219\u76f4\u63a5\u4e22\u5f03\u62a5\u6587\u3002<\/p>\n
      ACCEPT QUEUE\u961f\u5217\u5927\u5c0f\u53ef\u4ee5\u4f7f\u7528ss\u547d\u4ee4\u67e5\u770b<\/p>\n
      1. [<\/span>root@nginx2<\/span>.<\/span>proxy<\/span>.<\/span>qyer<\/span>.<\/span>idc <\/span>~]#<\/span>ss <\/span>-<\/span>ln<\/span><\/code><\/li>
      2. State<\/span>       <\/span>Recv<\/span>-<\/span>Q <\/span>Send<\/span>-<\/span>Q                                         <\/span>Local<\/span> <\/span>Address<\/span>:<\/span>Port<\/span>                                           <\/span>Peer<\/span> <\/span>Address<\/span>:<\/span>Port<\/span><\/code><\/li>
      3. LISTEN      <\/span>0<\/span>      <\/span>100<\/span>                                                <\/span>127.0<\/span>.<\/span>0.1<\/span>:<\/span>25<\/span>                                                        <\/span>*:*<\/span><\/code><\/li>
      4. LISTEN      <\/span>0<\/span>      <\/span>128<\/span>                                                        <\/span>*:<\/span>2233<\/span>                                                      <\/span>*:*<\/span><\/code><\/li>
      5. LISTEN      <\/span>0<\/span>      <\/span>511<\/span>                                                        <\/span>*:<\/span>443<\/span>                                                       <\/span>*:*<\/span><\/code><\/li>
      6. LISTEN      <\/span>0<\/span>      <\/span>128<\/span>                                                 <\/span>10.1<\/span>.<\/span>1.2<\/span>:<\/span>10050<\/span>                                                     <\/span>*:*<\/span><\/code><\/li>
      7. LISTEN      <\/span>0<\/span>      <\/span>511<\/span>                                                        <\/span>*:<\/span>80<\/span>                                                        <\/span>*:*<\/span><\/code><\/li>
      8. [<\/span>root@nginx2<\/span>.<\/span>proxy<\/span>.<\/span>qyer<\/span>.<\/span>idc <\/span>~]#<\/span><\/code><\/li><\/ol><\/pre>\n
        \u4f7f\u7528netstat -s \u53ef\u4ee5\u67e5\u770b\u88abACCEPT QUEUE\u961f\u5217\u961f\u5217\u4e22\u5f03\u7684\u6570\u636e\u3002<\/p>\n
        1. [<\/span>root@nginx2<\/span>.<\/span>proxy<\/span>.<\/span>qyer<\/span>.<\/span>idc <\/span>~]#<\/span>netstat <\/span>-<\/span>s <\/span>|<\/span> grep <\/span>\"times the listen queue of a socket overflowed\"<\/span><\/code><\/li>
        2.     <\/span>35552<\/span> times the listen queue of a socket overflowed<\/span><\/code><\/li>
        3. [<\/span>root@nginx2<\/span>.<\/span>proxy<\/span>.<\/span>qyer<\/span>.<\/span>idc <\/span>~]#<\/span><\/code><\/li><\/ol><\/pre>\n
          backlog\u7684\u503c\u4e0d\u5b9c\u8fc7\u5927\uff0cnginx\u548credis\u90fd\u662f\u4f7f\u7528\u7684511\u3002PHP\u66fe\u51fa\u73b0\u5c06\u6b64\u6570\u503c\u6539\u4e3a65535\u53c8\u6539\u56de\u6765\u7684\u60c5\u51b5\u3002\u8be6\u60c5\u53ef\u4ee5\u53c2\u8003\u8fd9\u7bc7\u6587\u7ae0\uff1a 
          \nhttp:\/\/www.cnxct.com\/something-about-phpfpm-s-backlog\/<\/a><\/p>\n
          \u4e24\u4e2a\u961f\u5217\u5927\u5c0f\u4e0d\u4e00\u81f4<\/h2>\n
          \u5f88\u660e\u663e\uff0c\u4ece\u4e0a\u9762\u4e3e\u4f8b\u6765\u770b\uff0c\u4e24\u4e2a\u961f\u5217\u5927\u5c0f\u5728\u5f88\u591a\u60c5\u51b5\u4e0b\u662f\u4e0d\u4e00\u81f4\u7684\u3002 
          \nACCEPT\u961f\u5217\u5927\u591a\u6570\u60c5\u51b5\u4e0b\u4f1a\u6bd4\u8f83\u5c0f\uff0c\u6240\u4ee5\u4f1a\u51fa\u73b0SYN QUEUE\u6ca1\u6709\u6ee1\uff0c\u800cACCEPT QUEUE\u6ee1\u4e86\u7684\u60c5\u51b5\uff0c\u6b64\u65f6\u4f1a\u6309\u7167tcp_aborton_overflow\u6765\u51b3\u5b9a\u76f4\u63a5\u4e22\u5f03\uff0c\u8fd8\u662f\u8fd4\u56de\u62d2\u7eddRST\u3002<\/p>\n
          \u800c\u5982\u679c\u542f\u7528\u4e86syncookies\uff0c\u90a3\u4e48syncookies\u4f1a\u5f00\u542f\uff0c\u9650\u5236SYN\u5305\u8fdb\u5165\u7684\u901f\u5ea6\u3002<\/p>\n
          SYN COOKIE\u95ee\u9898<\/h2>\n
          \u4e3a\u4e86\u5e94\u5bf9SYNflooding\uff08\u5373\u5ba2\u6237\u7aef\u53ea\u53d1\u9001SYN\u5305\u53d1\u8d77\u63e1\u624b\u800c\u4e0d\u56de\u5e94ACK\u5b8c\u6210\u8fde\u63a5\u5efa\u7acb\uff0c\u586b\u6ee1server\u7aef\u7684\u534a\u8fde\u63a5\u961f\u5217\uff0c\u8ba9\u5b83\u65e0\u6cd5\u5904\u7406\u6b63\u5e38\u7684\u63e1\u624b\u8bf7\u6c42\uff09\uff0cLinux\u5b9e\u73b0\u4e86\u4e00\u79cd\u79f0\u4e3aSYNcookie\u7684\u673a\u5236\uff0c\u901a\u8fc7net.ipv4.tcp_syncookies\u63a7\u5236\uff0c\u8bbe\u7f6e\u4e3a1\u8868\u793a\u5f00\u542f\u3002<\/p>\n
          \u7b80\u5355\u8bf4SYNcookie\u5c31\u662f\u5c06\u8fde\u63a5\u4fe1\u606f\u7f16\u7801\u5728ISN(initialsequencenumber)\u4e2d\u8fd4\u56de\u7ed9\u5ba2\u6237\u7aef\uff0c\u8fd9\u65f6server\u4e0d\u9700\u8981\u5c06\u534a\u8fde\u63a5\u4fdd\u5b58\u5728\u961f\u5217\u4e2d\uff0c\u800c\u662f\u5229\u7528\u5ba2\u6237\u7aef\u968f\u540e\u53d1\u6765\u7684ACK\u5e26\u56de\u7684ISN\u8fd8\u539f\u8fde\u63a5\u4fe1\u606f\uff0c\u4ee5\u5b8c\u6210\u8fde\u63a5\u7684\u5efa\u7acb\uff0c\u907f\u514d\u4e86\u534a\u8fde\u63a5\u961f\u5217\u88ab\u653b\u51fbSYN\u5305\u586b\u6ee1\u3002<\/p>\n
          \u5f53\u5f00\u542fsyn cookie\u4ee5\u540e\uff0c\u4e00\u65e6\u534a\u8fde\u63a5\u961f\u5217\uff08SYN QUEUE\uff09\u6ee1\u4e86\u7cfb\u7edf\u5c31\u4f1a\u542f\u7528syn cookie\u529f\u80fd\uff0c\u540c\u65f6\u5728\/var\/log\/messages\u8bb0\u5f55kernel: possible SYN flooding on port 80. Sending cookies\u3002<\/p>\n
          \u4f46\u6b64\u65f6\u961f\u5217\u7684\u5927\u5c0f\u5e76\u4e0d\u662ftcp_max_syn_backlog\u8bbe\u7f6e\u7684\u503c\uff0c\u800c\u662f\u7531\u4ee5\u4e0b3\u4e2a\u53c2\u6570\u6700\u5c0f\u503c\u51b3\u5b9a\u3002<\/p>\n
          \n
          SYN QUEUE\u961f\u5217\u957f\u5ea6=min(backlog,net.core.somaxconn\uff0ctcp_max_syn_backlog)\u3002<\/p>\n<\/blockquote>\n
          .<\/p>\n
          \u53c2\u8003\u8d44\u6599<\/h2>\n
          http:\/\/mp.weixin.qq.com\/s?__biz=MjM5NzUwNDA5MA==&mid=201005717&idx=1&sn=74036633114ee6212e57ee4576dbfcbc&3rd=MzA3MDU4NTYzMw==&scene=6#rd<\/a> 
          \n          http:\/\/gmd20.blog.163.com\/blog\/static\/16843923201471310322880\/<\/a> 
          \n          http:\/\/jaseywang.me\/2014\/07\/20\/tcp-queue-%E7%9A%84%E4%B8%80%E4%BA%9B%E9%97%AE%E9%A2%98\/<\/a> 
          \n          http:\/\/www.slideshare.net\/jooholee81\/tcp-summary<\/a> 
          \n          http:\/\/www.cnxct.com\/something-about-phpfpm-s-backlog\/<\/a> 
          \n          http:\/\/blog.dujiong.net\/2016\/09\/28\/tcp-backlog\/<\/a> 
          \n          http:\/\/www.jameswxx.com\/%E7%B3%BB%E7%BB%9F%E5%9F%BA%E7%A1%80\/%E5%85%B3%E4%BA%8Ebacklog\/<\/a> 
          \n          https:\/\/yq.aliyun.com\/articles\/4252<\/a><\/p>\n
          \u8f6c\u8f7d\u8bf7\u6ce8\u660e\uff1aIPCPU-\u7f51\u7edc\u4e4b\u8def<\/a> » TCP\u4e09\u6b21\u63e1\u624b-backlog\u961f\u5217\u95ee\u9898<\/a><\/p>","protected":false},"excerpt":{"rendered":"
          TCP\u4e09\u6b21\u63e1\u624b-backlog\u961f\u5217\u95ee\u9898.md \u6982\u8ff0 \u4e4b\u524d\u6709\u540c\u4e8b\u505a\u538b\u529b\u6d4b\u8bd5\u65f6\uff0c\u53d1\u73b0\u65e0\u8bba\u5982\u4f55\u90fd\u65e0\u6cd5\u7a81\u7834128\u5e76\u53d1\u7684\u95ee\u9898\uff0c\u7ecf\u6392\u67e5\u53d1\u73b0\u8be5\u670d\u52a1\u5668ACCEPT QUEUE\u961f\u5217\u90fd\u4e3a128\uff0c\u9650\u5236\u4e86\u7f51\u7edc\u7684\u5e76\u53d1\u3002 TCP\u4e09\u6b21\u63e1\u624b Linux\u5185\u6838\u534f\u8bae\u6808\u4e3a\u4e00\u4e2aTCP\u8fde\u63a5\u7ba1\u7406\u4f7f\u7528\u4e24\u4e2a\u961f\u5217\uff0c\u4e00\u4e2a\u662f\u534a\u94fe\u63a5\u961f\u5217SYN QUEUE\uff08\u7528\u6765\u4fdd\u5b58\u5904\u4e8eSYN_SENT\u548cSYN_RECV\u72b6\u6001\u7684\u8bf7\u6c42\uff09\uff0c\u4e00\u4e2a\u662fACCEPT\u961f\u5217 ACCEPT QUEUE\uff08\u7528\u6765\u4fdd\u5b58\u5904\u4e8eestablished\u72b6\u6001\uff0c\u4f46\u662f\u5e94\u7528\u5c42\u6ca1\u6709\u8c03\u7528accept\u53d6\u8d70\u7684\u8bf7\u6c42\uff09\u3002 \u5f53client \u5efa\u7acb\u8fde\u63a5\u65f6\u53d1\u9001SYN\u5305\u5230server\u7aef\uff0cserver\u6536\u5230\u4e4b\u540e\u5982\u679cSYN QUEUE\u961f\u5217\u5df2\u6ee1\uff0c\u76f4\u63a5\u4e22\u5f03\u4e0d\u56deACK\u3002\u5ba2\u6237\u7aef\u8d85\u65f6\u540e\u7ecf\u8fc73\u79d2\u30019\u79d2\u2026\u7684\u95f4\u9694\u65f6\u5019\u4e0d\u65ad\u91cd\u53d1SYN\u5305\u3002 \u5f53server\u7684SYN QUEUE\u6ca1\u6709\u6ee1\u65f6\uff0cserver\u4f1a\u56de\u590dSYN+ACK\u7ed9client\uff0c\u5982\u679cclient\u6536\u5230\u8bf7\u6c42\uff0c\u5219\u5c06\u72b6\u6001\u4fee\u6539\u4e3aESTABLISHED\uff0c\u5e76\u53d1\u9001ACK\u7ed9server\u3002 server\u6536\u5230ACK\uff0c\u5c06\u72b6\u6001\u4fee\u6539\u4e3aESTABLISHED\uff0c\u5e76\u628a\u8be5\u8bf7\u6c42\u4eceSYN QUEUE\u4e2d\u653e\u5230ACCEPT QUEUE\u3002 SYN QUEUE\u961f\u5217 \u7528\u4e8e\u4fdd\u5b58\u534a\u8fde\u63a5\u72b6\u6001\u7684\u8bf7\u6c42\uff0c\u5176\u5927\u5c0f\u901a\u8fc7\/proc\/sys\/net\/ipv4\/tcp_max_syn_backlog\u6307\u5b9a\u3002 SYN QUEUE\u961f\u5217\u957f\u5ea6\uff1atcp_max_syn_backlog \u901a\u8fc7netstat -s\u53ef\u4ee5\u67e5\u770b\u88abSYN QUEUE\u961f\u5217\u4e22\u5f03\u7684\u6570\u636e [root@nginx2.proxy.qyer.idc ~]#netstat -s | grep “SYNs to LISTEN sockets ignored” 35552 SYNs to LISTEN sockets ignored[root@nginx2.proxy.qyer.idc ~]# ACCEPT QUEUE\u961f\u5217 \u7528\u4e8e\u4fdd\u5b58\u5168\u8fde\u63a5\u72b6\u6001\u7684\u8bf7\u6c42\uff0c\u5176\u5927\u5c0f\u901a\u8fc7\/proc\/sys\/net\/core\/somaxconn\uff08\u9ed8\u8ba4\u662f128\uff09\u6307\u5b9a\uff0c\u5728\u4f7f\u7528listen\u51fd\u6570\u65f6\uff0c\u5185\u6838\u4f1a\u6839\u636e\u4f20\u5165\u7684backlog\u53c2\u6570\u4e0e\u7cfb\u7edf\u53c2\u6570somaxconn\u6bd4\u8f83\uff0c\u53d6\u4e8c\u8005\u7684\u8f83\u5c0f\u503c\u3002 ACCEPT QUEUE\u961f\u5217\u957f\u5ea6\uff1amin(backlog, somaxconn) \u5982\u679caccpet queue\u961f\u5217\u6ee1\u4e86\uff0cserver\u5c06\u5982\u4f55\u5904\u7406\u5462\uff1f\u53d6\u51b3\u4e8e\u4e00\u4e2a\u53c2\u6570tcp_aborton_overflow\uff0c\u5f53tcp_aborton_overflow\u53c2\u6570\u4e3a1\uff0c\u4f1a\u53d1\u9001 RST\uff1b\u5982\u679c\u4e3a0(\u9ed8\u8ba4\u503c)\uff0c\u5219\u76f4\u63a5\u4e22\u5f03\u62a5\u6587\u3002 ACCEPT QUEUE\u961f\u5217\u5927\u5c0f\u53ef\u4ee5\u4f7f\u7528ss\u547d\u4ee4\u67e5\u770b [root@nginx2.proxy.qyer.idc ~]#ss […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[13],"tags":[105,17,106,107,108,39,109],"_links":{"self":[{"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/posts\/699"}],"collection":[{"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/comments?post=699"}],"version-history":[{"count":0,"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/posts\/699\/revisions"}],"wp:attachment":[{"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/media?parent=699"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/categories?post=699"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c.ipcpu.com\/wp-json\/wp\/v2\/tags?post=699"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}