{"id":326,"date":"2013-08-09T11:37:28","date_gmt":"2013-08-09T11:37:28","guid":{"rendered":"a666587afda6e89aec274a3657558a27"},"modified":"2013-08-09T11:37:28","modified_gmt":"2013-08-09T11:37:28","slug":"","status":"publish","type":"post","link":"https:\/\/www.xiaobo.li\/notes\/archives\/326","title":{"rendered":"linux net status SYN_RECV"},"content":{"rendered":"

\u53ef\u4ee5\u901a\u8fc7\u4e0b\u9762\u8fd9\u4e2a\u547d\u4ee4\u6765\u7edf\u8ba1\u5f53\u524d\u8fde\u63a5\u6570<\/span>
\n<\/span><\/p>\n

\n
\n

netstat -n | awk '\/^tcp\/ {++S[$NF]} END {for(a in S) print a, S[a]}'<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

\n

\u8fd9\u6761\u8bed\u53e5\u8fd4\u56de\u7ed3\u679c\u5982\u4e0b<\/span><\/p>\n

\n
\n

 <\/p>\n<\/div>\n

\n
    \n
  1. TIME_WAIT 346<\/li>\n
  2. FIN_WAIT1 85<\/li>\n
  3. FIN_WAIT2 6<\/li>\n
  4. ESTABLISHED 1620<\/li>\n
  5. SYN_RECV 169<\/li>\n
  6. LAST_ACK 8<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

    <\/p>\n

    SYN_RECV\u8868\u793a\u6b63\u5728\u7b49\u5f85\u5904\u7406\u7684\u8bf7\u6c42\u6570\uff1b<\/span>ESTABLISHED<\/span>\u8868\u793a\u6b63\u5e38\u6570\u636e\u4f20\u8f93\u72b6\u6001\uff1b<\/span>TIME_WAIT<\/span>\u8868\u793a\u5904\u7406\u5b8c\u6bd5\uff0c\u7b49\u5f85\u8d85\u65f6\u7ed3\u675f\u7684\u8bf7\u6c42\u6570\u3002<\/span><\/span><\/p>\n

    \u72b6\u6001\uff1a\u63cf\u8ff0<\/span><\/p>\n

    CLOSED\uff1a\u65e0\u8fde\u63a5\u662f\u6d3b\u52a8\u7684\u6216\u6b63\u5728\u8fdb\u884c<\/span><\/span><\/p>\n

    LISTEN\uff1a\u670d\u52a1\u5668\u5728\u7b49\u5f85\u8fdb\u5165\u547c\u53eb<\/span><\/span><\/p>\n

    SYN_RECV\uff1a\u4e00\u4e2a\u8fde\u63a5\u8bf7\u6c42\u5df2\u7ecf\u5230\u8fbe\uff0c\u7b49\u5f85\u786e\u8ba4<\/span><\/span><\/p>\n

    SYN_SENT\uff1a\u5e94\u7528\u5df2\u7ecf\u5f00\u59cb\uff0c\u6253\u5f00\u4e00\u4e2a\u8fde\u63a5<\/span><\/span><\/p>\n

    ESTABLISHED\uff1a\u6b63\u5e38\u6570\u636e\u4f20\u8f93\u72b6\u6001<\/span><\/span><\/p>\n

    FIN_WAIT1\uff1a\u5e94\u7528\u8bf4\u5b83\u5df2\u7ecf\u5b8c\u6210<\/span><\/span><\/p>\n

    FIN_WAIT2\uff1a\u53e6\u4e00\u8fb9\u5df2\u540c\u610f\u91ca\u653e<\/span><\/span><\/p>\n

    ITMED_WAIT\uff1a\u7b49\u5f85\u6240\u6709\u5206\u7ec4\u6b7b\u6389<\/span><\/span><\/p>\n

    CLOSING\uff1a\u4e24\u8fb9\u540c\u65f6\u5c1d\u8bd5\u5173\u95ed<\/span><\/span><\/p>\n

    TIME_WAIT\uff1a\u53e6\u4e00\u8fb9\u5df2\u521d\u59cb\u5316\u4e00\u4e2a\u91ca\u653e<\/span><\/span><\/p>\n

    LAST_ACK\uff1a\u7b49\u5f85\u6240\u6709\u5206\u7ec4\u6b7b\u6389<\/span><\/span><\/p>\n

    \u53e6\u5916\u5f88\u591a\u4eba\u4f1a\u7528\u5230TCP SYN Flood<\/span>\u900f\u8fc7\u7f51\u8def\u5e95\u5c42\u5bf9\u670d\u52a1\u5668<\/span>Server<\/span>\u8fdb\u884c\u653b\u51fb\u7684\uff0c\u6211\u53ef\u4ee5\u7528<\/span><\/span>Iptables\u9632\u8303\u4e0b\uff1a<\/span><\/span><\/p>\n

    \u9632\u6b62\u540c\u6b65\u5305\u6d2a\u6c34\uff08Sync Flood<\/span>\uff09<\/span><\/span>
    \n<\/span><\/p>\n

    \n
    \n

     <\/p>\n<\/div>\n

    \n
      \n
    1. iptables -A FORWARD -p tcp --syn -m limit --limit 1\/s -j ACCEPT<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

      <\/p>\n


      \n<\/span>\u4e5f\u6709\u4eba\u5199\u4f5c<\/span><\/p>\n

      \n
      \n
        \n
      1. iptables -A INPUT -p tcp --syn -m limit --limit 1\/s -j ACCEPT<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

        <\/p>\n


        \n<\/span>--limit 1\/s \u9650\u5236<\/span>syn<\/span>\u5e76\u53d1\u6570\u6bcf\u79d2<\/span>1<\/span>\u6b21\uff0c\u53ef\u4ee5\u6839\u636e\u81ea\u5df1\u7684\u9700\u8981\u4fee\u6539<\/span><\/span>
        \n<\/span>\u9632\u6b62\u5404\u79cd\u7aef\u53e3\u626b\u63cf<\/span>
        \n<\/span><\/p>\n

        \n
        \n

         <\/p>\n<\/div>\n

        \n
          \n
        1. iptables -A FORWARD -p tcp --tcp-flags SYN,ACK,FIN,RST RST -m limit --limit 1\/s -j ACCEPT<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

          <\/p>\n


          \n<\/span>Ping\u6d2a\u6c34\u653b\u51fb\uff08<\/span>Ping of Death<\/span>\uff09<\/span><\/span>
          \n<\/span><\/p>\n

          \n
          \n

           <\/p>\n<\/div>\n

          \n
            \n
          1. iptables -A FORWARD -p icmp --icmp-type echo-request -m limit --limit 1\/s -j ACCEPT<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

            <\/p>\n

            \n

                \u540c\u65f6\uff0c\u5728\u521d\u59cb\u5316\u7cfb\u7edf\u8fc7\u7a0b\u4e2d\uff0c\u53ef\u4ee5\u5bf9\u670d\u52a1\u5668\u7684\u6570\u636e\u8fde\u63a5\u505a\u8bbe\u7f6e\uff0c\u4e0b\u9762\u7b80\u5355\u7684\u8bbe\u7f6e\u4e0b\uff0c\u5982\u679c\u6709\u5173\u4e8e\u8fd9\u65b9\u9762\u7684\u8bbe\u7f6e\uff0c\u6b22\u8fce\u5927\u5bb6\u5206\u4eab\u4e0b\uff0c\u5148\u8c22\u8fc7\u4e86<\/span>...<\/span><\/p>\n

            vi<\/span>m<\/span> \/etc\/sysctl.conf<\/span><\/p>\n

            net.ipv4.tcp_tw_reuse = 1<\/span><\/p>\n

            \u8be5\u6587\u4ef6\u8868\u793a\u662f\u5426\u5141\u8bb8\u91cd\u65b0\u5e94\u7528\u5904\u4e8eTIME-WAIT<\/span>\u72b6\u6001\u7684<\/span>socket<\/span>\u7528\u4e8e\u65b0\u7684<\/span>TCP<\/span>\u8fde\u63a5\u3002<\/span><\/span>
            \n<\/span>net.ipv4.tcp_tw_recycle = 1<\/span><\/p>\n

            recyse\u662f\u52a0\u901f<\/span>TIME-WAIT sockets<\/span>\u56de\u6536<\/span><\/span><\/p>\n

            \u5bf9tcp_tw_reuse<\/span>\u548c<\/span>tcp_tw_recycle<\/span>\u7684\u4fee\u6539\uff0c\u53ef\u80fd\u4f1a\u51fa\u73b0<\/span>.warning, got duplicate tcp line warning, got BOGUS tcp line.<\/span>\u4e0a\u9762\u8fd9\u4e8c\u4e2a\u53c2\u6570\u6307\u7684\u662f\u5b58\u5728\u8fd9\u4e24\u4e2a\u5b8c\u5168\u4e00\u6837\u7684<\/span>TCP<\/span>\u8fde\u63a5\uff0c\u8fd9\u4f1a\u53d1\u751f\u5728\u4e00\u4e2a\u8fde\u63a5\u88ab\u8fc5\u901f\u7684\u65ad\u5f00\u5e76\u4e14\u91cd\u65b0\u8fde\u63a5\u7684\u60c5\u51b5\uff0c\u800c\u4e14\u4f7f\u7528\u7684\u7aef\u53e3\u548c\u5730\u5740\u76f8\u540c\u3002\u4f46\u57fa\u672c \u4e0a\u8fd9\u6837\u7684\u4e8b\u60c5\u4e0d\u4f1a\u53d1\u751f\uff0c\u65e0\u8bba\u5982\u4f55\uff0c\u4f7f\u80fd\u4e0a\u8ff0\u8bbe\u7f6e\u4f1a\u589e\u52a0\u91cd\u73b0\u673a\u4f1a\u3002\u8fd9\u4e2a\u63d0\u793a\u4e0d\u4f1a\u6709\u4eba\u548c\u5371\u5bb3\uff0c\u800c\u4e14\u4e5f\u4e0d\u4f1a\u964d\u4f4e\u7cfb\u7edf\u6027\u80fd\uff0c\u76ee\u524d\u6b63\u5728\u8fdb\u884c\u5de5\u4f5c<\/span><\/span>
            \n<\/span> net.ipv4.tcp_syncookies = 1<\/span><\/p>\n

            \u8868\u793a\u5f00\u542fSYN Cookies<\/span>\u3002\u5f53\u51fa\u73b0<\/span>SYN<\/span>\u7b49\u5f85\u961f\u5217\u6ea2\u51fa\u65f6\uff0c\u542f\u7528<\/span>cookies<\/span>\u6765\u5904\u7406\uff0c\u53ef\u9632\u8303\u5c11\u91cf<\/span>SYN<\/span>\u653b\u51fb\uff0c\u9ed8\u8ba4\u4e3a<\/span>0<\/span>\uff0c\u8868\u793a\u5173\u95ed\uff1b<\/span><\/span>
            \n<\/span>net.ipv4.tcp_synack_retries = 1<\/span>
            \n<\/span>net.ipv4.tcp_keepalive_time = 1200<\/span><\/p>\n

            \u8868\u793a\u5f53keepalive<\/span>\u8d77\u7528\u7684\u65f6\u5019<\/span>,TCP<\/span>\u53d1\u9001<\/span>keepalive<\/span>\u6d88\u606f\u7684\u9891\u5ea6\u3002\u7f3a\u7701\u662f<\/span>2<\/span>\u5c0f\u65f6<\/span><\/span>
            \n<\/span>net.ipv4.tcp_fin_timeout = 30<\/span><\/p>\n

            fin_wait1\u72b6\u6001\u662f\u5728\u53d1\u8d77\u7aef\u4e3b\u52a8\u8981\u6c42\u5173\u95ed<\/span>tcp<\/span>\u8fde\u63a5\uff0c\u5e76\u4e14\u4e3b\u52a8\u53d1\u9001<\/span>fin<\/span>\u4ee5\u540e\uff0c\u7b49\u5f85\u63a5\u6536\u7aef\u56de\u590d<\/span>ack<\/span>\u65f6\u5019\u7684\u72b6\u6001\u3002\u5bf9\u4e8e\u672c\u7aef\u65ad\u5f00\u7684<\/span>socket<\/span>\u8fde\u63a5\uff0c<\/span>TCP<\/span>\u4fdd\u6301\u5728<\/span>FIN-WAIT-2<\/span>\u72b6\u6001\u7684\u65f6\u95f4\u3002\u5bf9\u65b9\u53ef\u80fd\u4f1a\u65ad\u5f00\u8fde\u63a5\u6216\u4e00\u76f4\u4e0d\u7ed3\u675f\u8fde\u63a5\u6216\u4e0d\u53ef\u9884\u6599\u7684\u8fdb\u7a0b\u6b7b\u4ea1\u3002<\/span><\/span>
            \n<\/span> net.ipv4.ip_local_port_range = 1024 65000<\/span>
            \n<\/span>net.ipv4.tcp_max_syn_backlog = 8192<\/span><\/p>\n

            \u8be5\u6587\u4ef6\u6307\u5b9a\u4e86\uff0c\u5728\u63a5\u53e3\u63a5\u6536\u6570\u636e\u5305\u7684\u901f\u7387\u6bd4\u5185\u6838\u5904\u7406\u8fd9\u4e9b\u5305\u7684\u901f\u7387\u5feb\u65f6\uff0c\u5141\u8bb8\u9001\u5230\u961f\u5217\u7684\u6570\u636e\u5305\u7684\u6700\u5927\u6570\u76ee\u3002<\/span>
            \n<\/span>net.ipv4.tcp_max_tw_buckets = 5000<\/span><\/p>\n

            \u4f7f\u8bbe\u7f6e\u751f\u6548<\/span><\/p>\n

            sysctl -p<\/span>  <\/span><\/p>\n

            \u53c2\u8003\u8d44\u6599\uff1a<\/span>http:\/\/blog.sina.com.cn\/s\/blog_416656f70100i08e.html<\/span><\/a><\/span><\/p>\n

                      http:\/\/baike.baidu.com\/view\/1520054.htm<\/a><\/span><\/p>\n

             <\/p>\n","protected":false},"excerpt":{"rendered":"

            \u53ef\u4ee5\u901a\u8fc7\u4e0b\u9762\u8fd9\u4e2a\u547d\u4ee4\u6765\u7edf\u8ba1\u5f53\u524d\u8fde\u63a5\u6570<\/span>
            \n<\/span><\/p>\n

            \n
            \n

            netstat -n | awk '\/^tcp\/ {++S[$NF]} END {for(a in S) print a, S[a]}'<\/p>\n<\/div>\n<\/div>\n

            <\/p>\n

            \u8fd9\u6761\u8bed\u53e5\u8fd4\u56de\u7ed3\u679c\u5982\u4e0b<\/span><\/p>\n

            \n
            \n

             <\/p>\n<\/div>\n

            \n
              \n
            1. TIME_WAIT 346<\/li>\n
            2. FIN_WAIT1 85<\/li>\n
            3. FIN_WAIT2 6<\/li>\n
            4. ESTABLISHED 1620<\/li>\n
            5. SYN_RECV 169<\/li>\n
            6. LAST_ACK 8<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

              <\/p>\n

              SYN_RECV\u8868\u793a\u6b63\u5728\u7b49\u5f85\u5904\u7406\u7684\u8bf7\u6c42\u6570\uff1b<\/span>ESTABLISHED<\/span>\u8868\u793a\u6b63\u5e38\u6570\u636e\u4f20\u8f93\u72b6\u6001\uff1b<\/span>TIME_WAIT<\/span>\u8868\u793a\u5904\u7406\u5b8c\u6bd5\uff0c\u7b49\u5f85\u8d85\u65f6\u7ed3\u675f\u7684\u8bf7\u6c42\u6570\u3002<\/span><\/span><\/p>\n

              \u72b6\u6001\uff1a\u63cf\u8ff0<\/span><\/p>\n

              CLOSED\uff1a\u65e0\u8fde\u63a5\u662f\u6d3b\u52a8\u7684\u6216\u6b63\u5728\u8fdb\u884c<\/span><\/span><\/p>\n

              LISTEN\uff1a\u670d\u52a1\u5668\u5728\u7b49\u5f85\u8fdb\u5165\u547c\u53eb<\/span><\/span><\/p>\n

              SYN_RECV\uff1a\u4e00\u4e2a...<\/span><\/span><\/p>\n

              \u7ee7\u7eed\u9605\u8bfb →<\/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":[287],"tags":[134,135],"class_list":["post-326","post","type-post","status-publish","format-standard","hentry","category-linux","tag-net","tag-status"],"_links":{"self":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts\/326","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/comments?post=326"}],"version-history":[{"count":0,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts\/326\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/media?parent=326"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/categories?post=326"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/tags?post=326"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}