{"id":36342,"date":"2026-09-29T16:42:13","date_gmt":"2026-09-29T08:42:13","guid":{"rendered":"https:\/\/www.varidata.com\/uncategorized-zh-tw\/how-to-spot-abnormal-traffic-on-a-server-using-tcpdump\/"},"modified":"2026-09-29T16:50:55","modified_gmt":"2026-09-29T08:50:55","slug":"how-to-spot-abnormal-traffic-on-a-server-using-tcpdump","status":"publish","type":"post","link":"https:\/\/www.varidata.com\/zh-tw\/knowledge-tc\/how-to-spot-abnormal-traffic-on-a-server-using-tcpdump\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528 tcpdump \u767c\u73fe\u4f3a\u670d\u5668\u4e0a\u7684\u7570\u5e38\u6d41\u91cf"},"content":{"rendered":"<p>\u4f60\u7684<a href=\"https:\/\/www.varidata.com\/zh-tw\/server\/hk\/\" target=\"_blank\">\u4f3a\u670d\u5668\u8b8a\u6162<\/a>\u4e86\u3002\u4f60\u57f7\u884c tcpdump\uff0c\u770b\u5230\u5927\u91cf SYN \u5c01\u5305\u6e67\u5165\u3002\u9019\u5c31\u662f\u7570\u5e38\u73fe\u8c61\u3002Tcpdump \u662f\u4e00\u6b3e\u547d\u4ee4\u5217\u6293\u5305\u5206\u6790\u5de5\u5177\uff0c\u53ef\u8b93\u4f60\u64f7\u53d6\u7db2\u8def\u6d41\u91cf\u3002\u63a5\u8457\uff0c\u4f60\u53ef\u4ee5\u5206\u6790\u6293\u5305\u7d50\u679c\uff0c\u5c0b\u627e\u5371\u96aa\u8a0a\u865f\u3002\u7570\u5e38\u884c\u70ba\u901a\u5e38\u8868\u73fe\u70ba\u4e0d\u5c0b\u5e38\u7684 TCP \u65d7\u6a19\u7d44\u5408\u3001\u904e\u9ad8\u7684<a href=\"https:\/\/www.varidata.com\/zh-tw\/blog-tc\/optimize-a-website-to-prevent-tcp-packet-loss-on-us-servers\/\" target=\"_blank\">\u5c01\u5305\u901f\u7387<\/a>\uff0c\u6216\u51fa\u4e4e\u610f\u6599\u7684\u6d41\u91cf\u4f86\u6e90\u3002\u5371\u96aa\u8a0a\u865f\u5305\u62ec\u7528\u6236\u7aef\u7121\u6cd5\u9023\u7dda\u3001\u91cd\u8907\u7684\u9023\u7dda\u5617\u8a66\uff0c\u6216\u7570\u5e38\u7684\u65d7\u6a19\u7d44\u5408\u3002Tcpdump \u6709\u52a9\u65bc\u6545\u969c\u6392\u9664\u3002\u4f60\u53ef\u4ee5\u4f9d\u7279\u5b9a\u65d7\u6a19\u9032\u884c\u904e\u6ffe\uff0c\u9032\u800c\u7406\u89e3\u6d41\u91cf\u6a21\u5f0f\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u95dc\u9375\u6307\u4ee4\u3001\u904e\u6ffe\u5668\u4ee5\u53ca\u89e3\u8b80\u6280\u5de7\uff0c\u5e6b\u52a9\u4f60\u53ca\u65e9\u767c\u73fe\u554f\u984c\u3002\u5148\u64f7\u53d6\u4e00\u90e8\u5206\u5c01\u5305\u6a23\u672c\uff0c\u7136\u5f8c\u958b\u59cb\u8b58\u5225\u7570\u5e38\u6a21\u5f0f\u3002<\/p>\n<h2>\u95dc\u9375\u91cd\u9ede<\/h2>\n<ul>\n<li>\n<p>\u5148\u64f7\u53d6\u6b63\u5e38\u6d41\u91cf\uff0c\u5efa\u7acb\u57fa\u6e96\uff0c\u4fbf\u65bc\u5f8c\u7e8c\u6bd4\u5c0d\u3002<\/p>\n<\/li>\n<li>\n<p>\u4f7f\u7528 tcpdump \u904e\u6ffe\u5668\u767c\u73fe SYN \u6d2a\u6cdb\u3001\u9023\u63a5\u57e0\u6383\u63cf\u4ee5\u53ca UDP\/ICMP \u7570\u5e38\u3002<\/p>\n<\/li>\n<li>\n<p>\u900f\u904e\u89e3\u8b80\u65d7\u6a19\u3001TTL \u548c\u5c01\u5305\u901f\u7387\u4f86\u8b58\u5225\u5371\u96aa\u8a0a\u865f\u3002<\/p>\n<\/li>\n<li>\n<p>\u5c07\u6293\u5305\u7d50\u679c\u5132\u5b58\u70ba pcap \u6a94\u6848\uff0c\u4ee5\u4fbf\u4f7f\u7528 Wireshark \u9032\u884c\u66f4\u6df1\u5165\u7684\u5206\u6790\u3002<\/p>\n<\/li>\n<li>\n<p>\u7d93\u5e38\u7df4\u7fd2\uff0c\u9010\u6b65\u5efa\u7acb\u8b58\u5225\u7570\u5e38\u6d41\u91cf\u7684\u4fe1\u5fc3\u3002<\/p>\n<\/li>\n<\/ul>\n<h2>\u4f7f\u7528 tcpdump \u64f7\u53d6\u57fa\u6e96\u7db2\u8def\u6d41\u91cf<\/h2>\n<p>\u5728\u4f60\u8457\u624b\u6392\u67e5\u7570\u5e38\u6a21\u5f0f\u4e4b\u524d\uff0c\u9700\u8981\u5148\u6709\u4e00\u500b\u53c3\u8003\u9ede\u3002\u4f60\u5fc5\u9808\u4e86\u89e3\u4f3a\u670d\u5668\u4e0a\u7684\u6b63\u5e38\u7db2\u8def\u6d41\u91cf\u662f\u4ec0\u9ebc\u6a23\u5b50\u3002\u7814\u7a76\u4eba\u54e1\u65e9\u5df2\u5c07\u9019\u500b\u601d\u8def\u7cfb\u7d71\u5316\u3002Qayyum \u7b49\u4eba\u63d0\u51fa\u4e86\u4e00\u7a2e\u57fa\u65bc\u7d71\u8a08\u5206\u6790\u7684\u7570\u5e38\u5075\u6e2c\u6280\u8853\uff0c\u5176\u6838\u5fc3\u5728\u65bc\u5efa\u7acb\u6b63\u5e38\u6d41\u91cf\u6a21\u578b\u3002\u4ed6\u5011\u5148\u8a2d\u5b9a\u6b63\u5e38\u57fa\u6e96\uff0c\u4efb\u4f55\u504f\u96e2\u8a72\u57fa\u6e96\u7684\u884c\u70ba\u90fd\u88ab\u8996\u70ba\u7570\u5e38\u6d41\u91cf\u3002\u9019\u500b\u904e\u7a0b\u6703\u589e\u5f37\u4f60\u7684\u5224\u65b7\u4fe1\u5fc3\u3002\u4f60\u6703\u77e5\u9053\u4f3a\u670d\u5668\u5728\u5065\u5eb7\u904b\u4f5c\u6642\u61c9\u8a72\u5448\u73fe\u600e\u6a23\u7684\u72c0\u614b\u3002<\/p>\n<blockquote>\n<p>Qayyum \u7b49\u4eba\u63d0\u51fa\u4e86\u4e00\u7a2e\u57fa\u65bc\u7d71\u8a08\u5206\u6790\u7684\u7db2\u8def\u7570\u5e38\u6d41\u91cf\u5075\u6e2c\u6280\u8853\uff0c\u5176\u91cd\u9ede\u5728\u65bc\u5efa\u7acb\u6b63\u5e38\u6d41\u91cf\u6a21\u578b\u4e26\u8a2d\u5b9a\u6b63\u5e38\u57fa\u6e96\u3002\u5728\u9032\u884c\u7570\u5e38\u6d41\u91cf\u5075\u6e2c\u6642\uff0c\u4efb\u4f55\u504f\u96e2\u8a72\u57fa\u6e96\u7684\u884c\u70ba\u90fd\u6703\u88ab\u8996\u70ba\u7570\u5e38\u6d41\u91cf\u3002<\/p>\n<\/blockquote>\n<p>\u4f60\u4e5f\u53ef\u4ee5\u7528 tcpdump \u63a1\u7528\u76f8\u540c\u7684\u601d\u8def\u3002\u5148\u5728\u6b63\u5e38\u904b\u4f5c\u671f\u9593\u64f7\u53d6\u6d41\u91cf\u3002Tcpdump \u70ba\u6b64\u63d0\u4f9b\u4e86\u4e00\u500b\u8f15\u91cf\u7d1a\u5de5\u5177\u3002\u4f60\u5f9e\u65e5\u5e38\u696d\u52d9\u6642\u6bb5\u958b\u59cb\u6293\u5305\uff0c\u518d\u900f\u904e\u5206\u6790\u9019\u4e9b\u6293\u5305\u7d50\u679c\uff0c\u5b78\u7fd2\u5178\u578b\u6d41\u91cf\u6a21\u5f0f\u3002<\/p>\n<h3>\u70ba\u4ecb\u9762\u6293\u5305\u8a2d\u5b9a Tcpdump<\/h3>\n<p>\u7b2c\u4e00\u6b65\u662f\u9078\u64c7\u6b63\u78ba\u7684\u7db2\u8def\u4ecb\u9762\u3002\u57f7\u884c <code>tcpdump -D<\/code> \u5217\u51fa\u53ef\u7528\u4ecb\u9762\u3002\u627e\u5230\u4f60\u7684\u5916\u90e8\u7db2\u8def\u4ecb\u9762\uff0c\u901a\u5e38\u540d\u7a31\u985e\u4f3c <code>eth0<\/code>\u3002\u56de\u9001\u4ecb\u9762\u8655\u7406\u7684\u662f\u5167\u90e8\u6d41\u91cf\uff0c\u800c\u4f60\u9700\u8981\u7684\u662f\u9023\u63a5\u4f3a\u670d\u5668\u8207\u5916\u90e8\u7db2\u8def\u7684\u90a3\u500b\u4ecb\u9762\u3002<\/p>\n<p>\u5982\u679c\u7cfb\u7d71\u4e2d\u5c1a\u672a\u5b89\u88dd tcpdump\uff0c\u8acb\u4f7f\u7528\u5957\u4ef6\u7ba1\u7406\u5668\u5b89\u88dd\u3002\u5728 Debian \u7cfb\u7d71\u4e0a\uff0c\u57f7\u884c <code>apt-get install tcpdump<\/code>\u3002\u5728 CentOS \u7cfb\u7d71\u4e0a\uff0c\u57f7\u884c <code>yum install tcpdump<\/code>\u3002<\/p>\n<p>\u63a5\u8457\u6e2c\u8a66\u74b0\u5883\u662f\u5426\u8a2d\u5b9a\u6b63\u78ba\u3002\u57f7\u884c <code>tcpdump -i eth0 -c 100<\/code>\u3002\u6b64\u6307\u4ee4\u6703\u8a18\u9304 100 \u500b\u5c01\u5305\u3002Tcpdump \u6703\u7acb\u5373\u986f\u793a\u6bcf\u500b\u5c01\u5305\u7684\u65d7\u6a19\u8207\u4f4d\u5740\u8cc7\u8a0a\uff0c\u4f60\u53ef\u4ee5\u5373\u6642\u770b\u5230\u8f38\u51fa\u3002<\/p>\n<h3>\u89c0\u5bdf\u6b63\u5e38\u7db2\u8def\u6d41\u91cf\u6a21\u5f0f<\/h3>\n<p>\u73fe\u5728\u958b\u59cb\u8490\u96c6\u57fa\u6e96\u6d41\u91cf\u3002\u9078\u64c7\u4e00\u500b\u696d\u52d9\u6b63\u5e38\u3001\u8ca0\u8f09\u5e73\u7a69\u7684\u6642\u6bb5\uff0c\u907f\u514d\u5c16\u5cf0\u671f\u3002\u57f7\u884c <code>tcpdump -i eth0 -c 1000 -w baseline.pcap<\/code>\u3002\u6b64\u6307\u4ee4\u6703\u975c\u9ed8\u64f7\u53d6 1000 \u500b\u5c01\u5305\uff0c\u4e26\u5c07\u5176\u5132\u5b58\u5230\u6a94\u6848\u4e2d\u3002\u9019\u4e9b\u8cc7\u6599\u5c07\u69cb\u6210\u4f60\u7684\u57fa\u6e96\uff0c\u7a0d\u5f8c\u4f60\u53ef\u4ee5\u85c9\u52a9 tcpdump \u904e\u6ffe\u5668\u9032\u884c\u5206\u6790\u3002<\/p>\n<p>\u8acb\u4ed4\u7d30\u7814\u7a76\u9019\u4efd\u57fa\u6e96\u8cc7\u6599\u3002\u89c0\u5bdf\u6d41\u91cf\u7d44\u6210\u3002Web \u4f3a\u670d\u5668\u901a\u5e38\u6703\u770b\u5230\u5927\u91cf\u5e36\u6709 SYN \u548c ACK \u65d7\u6a19\u7684\u5c01\u5305\uff0c\u800c\u4e14\u5927\u591a\u6578\u9023\u7dda\u90fd\u80fd\u5b8c\u6210\u4e09\u5411\u4ea4\u63e1\u3002\u5c01\u5305\u901f\u7387\u6703\u4fdd\u6301\u5e73\u7a69\uff0c\u4f86\u6e90\u4f4d\u5740\u4e5f\u6703\u4ee5\u53ef\u9810\u6e2c\u7684\u65b9\u5f0f\u91cd\u8907\u51fa\u73fe\u3002\u9019\u4e9b\u7db2\u8def\u6d41\u91cf\u63ed\u793a\u4e86\u5178\u578b\u6a21\u5f0f\u3002\u7279\u5225\u8981\u6ce8\u610f\u5c01\u5305\u901f\u7387\uff0c\u6b63\u5e38\u4f3a\u670d\u5668\u901a\u5e38\u8868\u73fe\u70ba\u7a69\u5b9a\u901f\u7387\uff0c\u800c\u7a81\u7136\u589e\u52a0\u5247\u53ef\u80fd\u610f\u5473\u8457\u554f\u984c\u3002\u540c\u6642\u8a18\u9304\u6b63\u5e38\u6642\u6bb5\u5e38\u898b\u7684\u4f86\u6e90 IP \u4f4d\u5740\u3002<\/p>\n<p>\u9019\u4efd\u57fa\u6e96\u5c07\u6709\u52a9\u65bc\u5f8c\u7e8c\u6545\u969c\u6392\u9664\u3002\u5c07\u65b0\u7684\u6293\u5305\u7d50\u679c\u8207\u57fa\u6e96\u6bd4\u5c0d\uff0c\u4efb\u4f55\u5dee\u7570\u90fd\u53ef\u80fd\u662f\u5371\u96aa\u8a0a\u865f\u3002\u5927\u91cf SYN \u5c01\u5305\u6703\u975e\u5e38\u986f\u773c\uff0cICMP \u56de\u61c9\u98a8\u66b4\u4e5f\u6703\u4e00\u76ee\u4e86\u7136\u3002\u9019\u4e9b\u904e\u6ffe\u5668\u53ef\u4ee5\u5e6b\u52a9\u4f60\u5feb\u901f\u9694\u96e2\u7279\u5b9a\u6a21\u5f0f\u3002\u4f60\u7684\u6293\u5305\u6280\u80fd\u6703\u8b93\u4f60\u66f4\u65e9\u767c\u73fe\u554f\u984c\u3002<\/p>\n<h2>\u4f7f\u7528 tcpdump \u64f7\u53d6\u4e26\u5206\u6790\u6d41\u91cf\u6a21\u5f0f<\/h2>\n<p>\u73fe\u5728\uff0c\u4f60\u8981\u5f9e\u5efa\u7acb\u57fa\u6e96\u8f49\u5411\u5be6\u969b\u5075\u6e2c\u3002\u4f60\u5c07\u4f7f\u7528 tcpdump \u4f86\u64f7\u53d6\u4e26\u5206\u6790\u4f3a\u670d\u5668\u4e0a\u7684\u7db2\u8def\u6d41\u91cf\u3002\u95dc\u9375\u6280\u80fd\u5728\u65bc\u7de8\u5beb\u6b63\u78ba\u7684\u904e\u6ffe\u5668\u3002Tcpdump \u53ef\u4ee5\u8b93\u4f60\u7cbe\u6e96\u64f7\u53d6\u4e26\u7be9\u9078\u7db2\u8def\u5c01\u5305\uff0c\u9019\u4e9b\u904e\u6ffe\u5668\u80fd\u5920\u5c07\u7279\u5b9a\u7570\u5e38\u5f9e\u6b63\u5e38\u7db2\u8def\u6d41\u91cf\u4e2d\u5206\u96e2\u51fa\u4f86\u3002\u4f60\u53ef\u4ee5\u642d\u914d <code>-l<\/code> \u53c3\u6578\u9032\u884c\u5373\u6642\u76e3\u63a7\uff0c\u8a72\u53c3\u6578\u6703\u555f\u7528\u884c\u7de9\u885d\uff0c\u8b93\u8f38\u51fa\u5728\u5c01\u5305\u5230\u9054\u6642\u7acb\u5373\u986f\u793a\u3002\u5c07\u904e\u6ffe\u5668\u8207\u5373\u6642\u8f38\u51fa\u7d50\u5408\u4f7f\u7528\uff0c\u80fd\u5920\u5feb\u901f\u767c\u73fe\u7570\u5e38\u3002<\/p>\n<h3>\u904e\u6ffe SYN \u6d2a\u6cdb\u8207\u9023\u63a5\u57e0\u6383\u63cf<\/h3>\n<p>SYN \u6d2a\u6cdb\u6703\u7559\u4e0b\u975e\u5e38\u6e05\u695a\u7684\u8de1\u8c61\u3002\u4f60\u6703\u770b\u5230\u5927\u91cf SYN \u5c01\u5305\uff0c\u537b\u5e7e\u4e4e\u6c92\u6709\u5f8c\u7e8c ACK\u3002\u4f60\u9700\u8981\u4e00\u500b\u53ea\u64f7\u53d6\u9019\u4e9b\u521d\u59cb\u4ea4\u63e1\u8acb\u6c42\u7684\u904e\u6ffe\u5668\u3002Berkeley Packet Filter \u8a9e\u6cd5\uff0c\u4e5f\u7a31 berkeley packet filter syntax\uff0c\u5141\u8a31\u4f60\u57fa\u65bc\u5354\u5b9a\u6a19\u982d\u4e2d\u7684\u4f4d\u5143\u7d44\u504f\u79fb\u7de8\u5beb\u904e\u6ffe\u689d\u4ef6\u3002\u9019\u7a2e\u65b9\u6cd5\u80fd\u5c0d\u5c01\u5305\u9078\u64c7\u9032\u884c\u7cbe\u7d30\u63a7\u5236\u3002<\/p>\n<p>\u5148\u5f9e\u5373\u6642\u904e\u6ffe\u958b\u59cb\u3002\u57f7\u884c <code>tcpdump -i eth0 -l \"tcp[13] == 0x02\"<\/code>\u3002\u4f60\u6703\u770b\u5230\u6240\u6709\u9032\u5165\u4f3a\u670d\u5668\u7684 SYN \u5c01\u5305\u3002\u6b63\u5e38\u4f3a\u670d\u5668\u901a\u5e38\u6703\u6709\u7a69\u5b9a\u7684 SYN \u6d41\u91cf\uff0c\u800c\u5728\u906d\u9047\u6d2a\u6cdb\u6642\uff0c\u4f60\u6703\u770b\u5230\u77ed\u6642\u9593\u5167\u51fa\u73fe\u5927\u91cf SYN\uff0c\u537b\u6c92\u6709\u5c0d\u61c9\u9023\u7dda\u5b8c\u6210\u5f8c\u7684 ACK\u3002\u82e5\u67d0\u4e00\u4f86\u6e90\u6bcf\u79d2\u767c\u51fa\u6578\u767e\u500b\u4ee5\u4e0a SYN \u5c01\u5305\uff0c\u5c31\u53ef\u80fd\u610f\u5473\u8457\u653b\u64ca\u3002\u4f60\u8981\u6301\u7e8c\u89c0\u5bdf\u901f\u7387\u8b8a\u5316\uff0c\u4e26\u8207\u4e4b\u524d\u5efa\u7acb\u7684\u57fa\u6e96\u5c0d\u7167\u3002\u5dee\u7570\u901a\u5e38\u6703\u7acb\u523b\u986f\u73fe\u51fa\u4f86\u3002<\/p>\n<p>\u9023\u63a5\u57e0\u6383\u63cf\u7684\u8868\u73fe\u5247\u4e0d\u540c\u3002\u6383\u63cf\u5668\u6703\u4f9d\u5e8f\u5411\u4e0d\u540c\u9023\u63a5\u57e0\u5206\u5225\u9001\u51fa SYN \u5c01\u5305\u3002\u4f60\u6703\u5728\u77ed\u6642\u9593\u5167\u770b\u5230\u67d0\u4e00\u4f86\u6e90\u4f4d\u5740\u5b58\u53d6\u8a31\u591a\u4e0d\u540c\u7684\u76ee\u6a19\u9023\u63a5\u57e0\u3002\u57f7\u884c <code>tcpdump -i eth0 -l -nn \"tcp[13] == 0x02\"<\/code>\u3002\u53c3\u6578 <code>-nn<\/code> \u6703\u963b\u6b62 DNS \u89e3\u6790\uff0c\u9019\u6a23\u4f60\u5c31\u80fd\u6e05\u695a\u770b\u5230\u539f\u59cb IP \u4f4d\u5740\u548c\u9023\u63a5\u57e0\u865f\u78bc\u3002\u5982\u679c\u4e00\u500b IP \u5728\u77ed\u6642\u9593\u5167\u63a2\u6e2c\u5927\u91cf\u9023\u63a5\u57e0\uff0c\u901a\u5e38\u8868\u793a\u5b83\u6b63\u5728\u9032\u884c\u5075\u5bdf\u3002\u4f60\u53ef\u4ee5\u85c9\u52a9 tcpdump \u4f9d\u9023\u63a5\u57e0\u904e\u6ffe\uff0c\u5f9e\u800c\u66f4\u6e05\u695a\u5730\u770b\u5230\u9019\u4e00\u6a21\u5f0f\u3002<\/p>\n<p>\u4f60\u9084\u53ef\u4ee5\u4f9d\u4e3b\u6a5f\u904e\u6ffe\uff0c\u55ae\u7368\u9396\u5b9a\u4e00\u500b\u53ef\u7591\u4f86\u6e90\u3002\u5728\u904e\u6ffe\u689d\u4ef6\u4e2d\u52a0\u5165 <code>and src host X.X.X.X<\/code>\u3002Tcpdump \u5c31\u6703\u5c07\u8996\u91ce\u7e2e\u5c0f\u5230\u9019\u4e00\u500b\u653b\u64ca\u8005\u3002\u9019\u6a23\u4f60\u4fbf\u80fd\u66f4\u7d30\u7dfb\u5730\u5206\u6790\u5176\u884c\u70ba\u6a21\u5f0f\u3001\u6383\u63cf\u65b9\u5f0f\u548c\u76ee\u6a19\u9078\u64c7\u3002<\/p>\n<h3>\u8b58\u5225 UDP \u548c ICMP \u7570\u5e38<\/h3>\n<p>UDP \u7570\u5e38\u9700\u8981\u4e0d\u540c\u7684\u904e\u6ffe\u5668\u3002DNS \u653e\u5927\u653b\u64ca\u5927\u91cf\u4f9d\u8cf4 UDP\u3002\u653b\u64ca\u8005\u6703\u5411 DNS \u4f3a\u670d\u5668\u9001\u51fa\u4e00\u500b\u5f88\u5c0f\u7684\u67e5\u8a62\u8acb\u6c42\uff0c\u4e26\u507d\u9020\u4f86\u6e90 IP \u4f4d\u5740\uff0c\u63a5\u8457\u8a72\u4f3a\u670d\u5668\u6703\u5c07\u4e00\u500b\u66f4\u5927\u7684\u56de\u61c9\u767c\u7d66\u53d7\u5bb3\u8005\u3002\u57f7\u884c <code>tcpdump -i eth0 -l \"udp dst port 53\"<\/code>\u3002\u4f60\u6703\u770b\u5230\u5927\u91cf\u767c\u5f80 53 \u9023\u63a5\u57e0\u7684 UDP \u5c01\u5305\uff0c\u4e14\u5927\u5c0f\u5404\u4e0d\u76f8\u540c\u3002\u6b63\u5e38\u67e5\u8a62\u901a\u5e38\u6703\u7522\u751f\u5c0f\u65bc 512 \u4f4d\u5143\u7d44\u7684\u56de\u61c9\uff0c\u800c\u66f4\u5927\u7684\u56de\u61c9\u5247\u53ef\u80fd\u610f\u5473\u8457\u653e\u5927\u653b\u64ca\u3002\u4f60\u53ef\u4ee5\u7d71\u8a08\u56de\u61c9\u5927\u5c0f\uff0c\u4ee5\u78ba\u8a8d\u9019\u7a2e\u7570\u5e38\u3002<\/p>\n<p>ICMP \u7570\u5e38\u5247\u5305\u62ec ping \u6d2a\u6cdb\u3002\u653b\u64ca\u8005\u6703\u4ee5\u6975\u9ad8\u983b\u7387\u9001\u51fa ICMP \u56de\u61c9\u8acb\u6c42\u3002\u4f3a\u670d\u5668\u6bcf\u6b21\u90fd\u56de\u61c9\uff0c\u56e0\u800c\u6d88\u8017\u983b\u5bec\u3002\u57f7\u884c <code>tcpdump -i eth0 -l \"icmp and icmp[icmptype] == 8\"<\/code>\u3002\u6b64\u904e\u6ffe\u5668\u53ea\u64f7\u53d6\u56de\u61c9\u8acb\u6c42\u3002\u6b63\u5e38\u4f3a\u670d\u5668\u901a\u5e38\u53ea\u6703\u5076\u723e\u6536\u5230\u4f86\u81ea\u76e3\u63a7\u5de5\u5177\u7684 ping\uff0c\u800c\u6d2a\u6cdb\u653b\u64ca\u5247\u6703\u8868\u73fe\u70ba\u67d0\u4e00\u4f86\u6e90\u6bcf\u79d2\u9001\u51fa\u6578\u767e\u500b\u8acb\u6c42\uff0c\u9019\u7a2e\u6d41\u91cf\u6a21\u5f0f\u6703\u975e\u5e38\u660e\u986f\u3002<\/p>\n<p>\u5728\u64f7\u53d6\u4e26\u5206\u6790\u7db2\u8def\u6d41\u91cf\u6642\uff0c\u4f60\u9084\u61c9\u95dc\u6ce8 TTL \u503c\u3002\u6b63\u5e38 ICMP \u5c01\u5305\u7684 TTL \u901a\u5e38\u6703\u56e0\u4f86\u6e90\u4e0d\u540c\u800c\u4fdd\u6301\u4e00\u5b9a\u898f\u5f8b\u3002\u5982\u679c\u540c\u4e00\u500b\u4f86\u6e90 IP \u7684 TTL \u7a81\u7136\u767c\u751f\u8b8a\u5316\uff0c\u5c31\u53ef\u80fd\u610f\u5473\u8457\u4f86\u6e90\u4f4d\u5740\u88ab\u507d\u9020\u3002Tcpdump \u53ef\u4ee5\u5e6b\u52a9\u4f60\u8b58\u5225\u9019\u7a2e\u4e0d\u4e00\u81f4\u3002<\/p>\n<p>\u9019\u4e9b\u904e\u6ffe\u5668\u69cb\u6210\u4e86\u4f60\u7684\u5075\u6e2c\u5de5\u5177\u7bb1\u3002\u4f60\u9700\u8981\u53cd\u8986\u7df4\u7fd2\uff0c\u719f\u6089\u6bcf\u4e00\u7a2e\u904e\u6ffe\u65b9\u5f0f\uff0c\u4e26\u6839\u64da\u81ea\u8eab\u74b0\u5883\u9032\u884c\u8abf\u6574\u3002\u9019\u500b\u904e\u7a0b\u96e2\u4e0d\u958b\u6301\u7e8c\u6293\u5305\u3002\u4f60\u6703\u9010\u6f38\u638c\u63e1\u5982\u4f55\u6709\u6548\u5730\u64f7\u53d6\u4e26\u5206\u6790\u6d41\u91cf\uff0c\u5b78\u6703\u70ba\u767c\u73fe\u6a21\u5f0f\u800c\u5206\u6790\u7db2\u8def\u6d41\u91cf\uff0c\u4e5f\u5b78\u6703\u70ba\u4e8b\u5f8c\u5fa9\u76e4\u800c\u4fdd\u7559\u6293\u5305\u8cc7\u6599\u3002\u4f60\u8981\u628a tcpdump \u7576\u4f5c\u4e3b\u8981\u5de5\u5177\uff0c\u8a8d\u771f\u5206\u6790\u6bcf\u4e00\u4efd\u6293\u5305\u7d50\u679c\uff0c\u5b9a\u671f\u91cd\u8907\u9019\u4e9b\u64f7\u53d6\u548c\u5206\u6790\u904e\u7a0b\u3002\u6301\u7e8c\u7df4\u7fd2\u6703\u4e0d\u65b7\u589e\u5f37\u4f60\u7684\u5224\u65b7\u80fd\u529b\u3002<\/p>\n<h2>\u89e3\u8b80 Tcpdump \u8f38\u51fa\u4e2d\u7684\u5371\u96aa\u8a0a\u865f<\/h2>\n<p>\u5982\u679c\u4e0d\u6703\u6b63\u78ba\u89e3\u8b80\uff0c\u539f\u59cb\u8f38\u51fa\u672c\u8eab\u610f\u7fa9\u4e26\u4e0d\u5927\u3002\u4f60\u5fc5\u9808\u9010\u9805\u5206\u6790\u6bcf\u500b\u6b04\u4f4d\uff0c\u4e26\u5c07\u5176\u8207\u57fa\u6e96\u9032\u884c\u6bd4\u5c0d\u3002\u53ea\u6709\u9019\u6a23\uff0c\u5927\u7247\u7684\u6587\u5b57\u624d\u6703\u8f49\u5316\u70ba\u6e05\u695a\u7684\u8a3a\u65b7\u7d50\u8ad6\u3002<\/p>\n<h3>\u89e3\u78bc\u65d7\u6a19\u3001TTL \u548c\u5c01\u5305\u901f\u7387<\/h3>\n<p>TCP \u65d7\u6a19\u6b04\u4f4d\u8b1b\u8ff0\u4e86\u6bcf\u4e00\u689d\u9023\u7dda\u7684\u6545\u4e8b\u3002\u4e00\u500b\u5065\u5eb7\u7684\u4ea4\u63e1\u904e\u7a0b\u61c9\u7576\u4f9d\u5e8f\u51fa\u73fe SYN\u3001SYN-ACK\u3001ACK\u3002\u4f60\u9700\u8981\u5728 tcpdump \u8f38\u51fa\u4e2d\u89c0\u5bdf\u9019\u4e00\u5e8f\u5217\u3002\u5982\u679c\u770b\u5230\u4e00\u9023\u4e32 SYN \u537b\u6c92\u6709\u56de\u61c9\uff0c\u5c31\u53ef\u80fd\u8868\u793a\u906d\u9047\u4e86\u6d2a\u6cdb\u653b\u64ca\uff0c\u6216\u8005\u76ee\u6a19\u9023\u63a5\u57e0\u88ab\u963b\u65b7\u3002RST \u65d7\u6a19\u8868\u793a\u9023\u7dda\u88ab\u62d2\u7d55\u3002\u5982\u679c\u67d0\u4e00\u4e3b\u6a5f\u767c\u51fa\u5927\u91cf RST\uff0c\u5247\u5f80\u5f80\u610f\u5473\u8457\u6709\u6383\u63cf\u5668\u6b63\u5728\u63a2\u6e2c\u95dc\u9589\u7684\u9023\u63a5\u57e0\u3002<\/p>\n<p>TTL \u503c\u53ef\u4ee5\u53cd\u6620\u5c01\u5305\u7684\u5927\u81f4\u4f86\u6e90\u3002\u4e0d\u540c\u4f5c\u696d\u7cfb\u7d71\u6703\u8a2d\u5b9a\u5404\u81ea\u9810\u8a2d\u7684 TTL\u3002\u5728\u6b63\u5e38\u60c5\u6cc1\u4e0b\uff0c\u540c\u4e00\u4f86\u6e90\u767c\u51fa\u7684\u5c01\u5305 TTL \u5f80\u5f80\u8f03\u70ba\u4e00\u81f4\u3002\u5982\u679c\u67d0\u500b\u4f4d\u5740\u7684 TTL \u7a81\u7136\u8b8a\u5316\uff0c\u5c31\u53ef\u80fd\u6697\u793a\u5b58\u5728\u507d\u88dd\u6216\u6b3a\u9a19\u3002\u653b\u64ca\u8005\u5f88\u5c11\u80fd\u7cbe\u78ba\u6a21\u64ec\u88ab\u5192\u5145\u4e3b\u6a5f\u539f\u672c\u7684 TTL\u3002<\/p>\n<p>\u5c01\u5305\u901f\u7387\u901a\u5e38\u662f\u6700\u6e05\u695a\u7684\u7570\u5e38\u8a0a\u865f\u3002Tcpdump \u6703\u5728\u6bcf\u4e00\u884c\u8f38\u51fa\u6642\u9593\u6233\u8a18\u3002\u4f60\u53ef\u4ee5\u64da\u6b64\u7d71\u8a08\u6bcf\u79d2\u5230\u9054\u7684\u5c01\u5305\u6578\u91cf\u3002\u57fa\u6e96\u901a\u5e38\u6703\u5448\u73fe\u7a69\u5b9a\u7bc0\u594f\uff0c\u800c\u4e00\u65e6\u51fa\u73fe\u4e09\u500d\u4ee5\u4e0a\u7684\u7a81\u589e\uff0c\u5c31\u503c\u5f97\u8b66\u60d5\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528\u5e36\u6709 <code>-tttt<\/code> \u53c3\u6578\u7684 tcpdump \u4f86\u986f\u793a\u5b8c\u6574\u6642\u9593\u6233\u8a18\uff0c\u5f9e\u800c\u66f4\u6e96\u78ba\u5730\u8861\u91cf\u5c01\u5305\u4e4b\u9593\u7684\u6642\u9593\u9593\u9694\u3002\u5982\u679c\u4f60\u770b\u5230\u6210\u5343\u4e0a\u842c\u7684\u5c01\u5305\u4e4b\u9593\u9593\u9694\u6975\u77ed\uff0c\u90a3\u5f80\u5f80\u610f\u5473\u8457\u5b83\u5011\u4f86\u81ea\u81ea\u52d5\u5316\u5de5\u5177\uff0c\u800c\u975e\u771f\u5be6\u4f7f\u7528\u8005\u884c\u70ba\u3002<\/p>\n<h3>\u8b58\u5225\u91cd\u8907\u9023\u7dda\u8207\u7570\u5e38\u4f86\u6e90<\/h3>\n<p>\u91cd\u8907\u884c\u70ba\u6703\u66b4\u9732\u610f\u5716\u3002\u4e00\u500b\u6b63\u5e38\u7528\u6236\u7aef\u6703\u5efa\u7acb\u4e00\u689d\u9023\u7dda\uff0c\u5b8c\u6210\u64cd\u4f5c\u5f8c\u7d50\u675f\uff1b\u800c\u653b\u64ca\u8005\u53ef\u80fd\u6703\u5728\u5e7e\u79d2\u9418\u5167\u5efa\u7acb\u6578\u767e\u689d\u9023\u7dda\u3002\u4f60\u53ef\u4ee5\u5c0d\u55ae\u4e00\u4f86\u6e90\u4f4d\u5740\u9032\u884c\u904e\u6ffe\uff0c\u7136\u5f8c\u7d71\u8a08\u5176\u51fa\u73fe\u6b21\u6578\u3002Tcpdump \u85c9\u52a9\u4e3b\u6a5f\u904e\u6ffe\u5668\u5c31\u80fd\u8f15\u9b06\u505a\u5230\u9019\u4e00\u9ede\u3002\u63a5\u8457\uff0c\u4f60\u518d\u7d50\u5408\u9023\u63a5\u57e0\u548c\u65d7\u6a19\u6a21\u5f0f\u9032\u884c\u5206\u6790\u3002<\/p>\n<p>\u7570\u5e38\u4f86\u6e90\u901a\u5e38\u6703\u4ee5\u591a\u7a2e\u65b9\u5f0f\u66b4\u9732\u51fa\u4f86\u3002\u4f60\u53ef\u80fd\u6703\u770b\u5230\u4f86\u81ea\u4f60\u4e26\u7121\u4f7f\u7528\u8005\u5206\u5e03\u5730\u5340\u7684\u4f4d\u5740\uff1b\u4e5f\u53ef\u80fd\u770b\u5230\u5167\u90e8\u4f4d\u5740\u7a81\u7136\u8207\u5f9e\u672a\u806f\u7e6b\u904e\u7684\u5916\u90e8\u4e3b\u6a5f\u901a\u8a0a\uff1b\u9084\u53ef\u80fd\u770b\u5230\u67d0\u4e00\u4f4d\u5740\u4f9d\u5e8f\u5b58\u53d6\u5927\u91cf\u9023\u63a5\u57e0\u3002\u4e0d\u540c\u6a21\u5f0f\u53cd\u6620\u4e0d\u540c\u5a01\u8105\u3002\u4e00\u500b\u4f4d\u5740\u4f9d\u6b21\u63a2\u6e2c\u6240\u6709\u9023\u63a5\u57e0\uff0c\u901a\u5e38\u662f\u5075\u5bdf\u884c\u70ba\uff1b\u4e00\u500b\u4f4d\u5740\u53cd\u8986\u9001\u51fa\u76f8\u540c\u8f09\u8377\uff0c\u5247\u53ef\u80fd\u662f\u66b4\u529b\u5617\u8a66\u3002<\/p>\n<p>\u4f60\u9084\u61c9\u95dc\u6ce8\u534a\u958b\u9023\u7dda\u3002\u9019\u985e\u9023\u7dda\u8868\u73fe\u70ba\u53ea\u770b\u5230 SYN\uff0c\u537b\u6c92\u6709\u5b8c\u6210\u6700\u7d42 ACK\u3002\u7576\u4f3a\u670d\u5668\u8cc7\u6e90\u8017\u76e1\u6642\uff0c\u9019\u985e\u9023\u7dda\u6703\u4e0d\u65b7\u5806\u7a4d\u3002Tcpdump \u6703\u5728\u65d7\u6a19\u6b04\u4e2d\u6e05\u695a\u5730\u986f\u793a\u5b83\u5011\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528\u904e\u6ffe\u5668\u5c07\u9019\u4e9b\u5c01\u5305\u55ae\u7368\u63d0\u53d6\u51fa\u4f86\uff0c\u4e26\u6e2c\u91cf\u5b83\u5011\u7684\u6578\u91cf\u3002\u5982\u679c\u8a08\u6578\u6301\u7e8c\u4e0a\u5347\uff0c\u90a3\u5c31\u8868\u793a\u554f\u984c\u6b63\u5728\u60e1\u5316\u3002<\/p>\n<p>\u4f60\u7684\u76ee\u6a19\u662f\u8a3a\u65b7\uff0c\u800c\u4e0d\u662f\u731c\u6e2c\u3002\u8981\u5c07\u6bcf\u4e00\u500b\u5371\u96aa\u8a0a\u865f\u90fd\u8207\u57fa\u6e96\u9032\u884c\u6bd4\u5c0d\uff0c\u518d\u900f\u904e\u7b2c\u4e8c\u6b21\u6293\u5305\u52a0\u4ee5\u78ba\u8a8d\uff0c\u96a8\u5f8c\u57fa\u65bc\u5145\u5206\u8b49\u64da\u63a1\u53d6\u884c\u52d5\u3002<\/p>\n<h2>\u6293\u5305\u4e2d\u7684\u771f\u5be6\u653b\u64ca\u6a21\u5f0f<\/h2>\n<h3>\u5075\u6e2c UDP \u7570\u5e38\uff08DNS \u653e\u5927\u3001Ping \u6d2a\u6cdb\uff09<\/h3>\n<p>\u4f60\u53ef\u4ee5\u4f7f\u7528 tcpdump \u8b58\u5225 DNS \u653e\u5927\u653b\u64ca\u3002\u653b\u64ca\u8005\u6703\u5411\u958b\u653e\u89e3\u6790\u5668\u9001\u51fa\u4e00\u500b\u5f88\u5c0f\u7684\u67e5\u8a62\u8acb\u6c42\uff0c\u4e26\u507d\u9020\u4f86\u6e90 IP \u4f4d\u5740\uff0c\u800c\u89e3\u6790\u5668\u6703\u5c07\u66f4\u5927\u7684\u56de\u61c9\u767c\u56de\u4f60\u7684\u4f3a\u670d\u5668\u3002\u4f60\u53ef\u4ee5\u900f\u904e\u904e\u6ffe UDP 53 \u9023\u63a5\u57e0\u6d41\u91cf\u4f86\u5075\u6e2c\u9019\u4e00\u73fe\u8c61\uff0c\u91cd\u9ede\u95dc\u6ce8\u8d85\u904e 512 \u4f4d\u5143\u7d44\u7684\u56de\u61c9\u3002\u6b63\u5e38 DNS \u56de\u61c9\u901a\u5e38\u4f4e\u65bc\u9019\u4e00\u9580\u6abb\uff0c\u800c\u8d85\u5927\u56de\u61c9\u5247\u53ef\u80fd\u610f\u5473\u8457\u6feb\u7528\u3002Tcpdump \u6703\u986f\u793a\u6bcf\u500b\u8d85\u5927\u56de\u61c9\u7684\u4f86\u6e90\u4f4d\u5740\u3002\u5982\u679c\u4f60\u770b\u5230\u540c\u4e00\u500b\u89e3\u6790\u5668\u6301\u7e8c\u5411\u540c\u4e00\u76ee\u6a19\u9001\u51fa\u5927\u91cf\u5927\u5c01\u5305\u56de\u61c9\uff0c\u5c31\u53ef\u4ee5\u78ba\u8a8d\u653b\u64ca\u6b63\u5728\u9032\u884c\u3002\u4f60\u9084\u53ef\u4ee5\u8ffd\u8e64\u5c01\u5305\u901f\u7387\uff0c\u4ee5\u8861\u91cf\u653b\u64ca\u5f37\u5ea6\u3002<\/p>\n<p>Ping \u6d2a\u6cdb\u6703\u8868\u73fe\u70ba ICMP \u56de\u61c9\u8acb\u6c42\u7684\u5bc6\u96c6\u7a81\u767c\u3002\u4f7f\u7528 tcpdump \u642d\u914d ICMP type 8 \u56de\u61c9\u8acb\u6c42\u904e\u6ffe\u5668\u57f7\u884c\uff0c\u5c31\u80fd\u5c07\u56de\u61c9\u8acb\u6c42\u5f9e\u5176\u4ed6\u8cc7\u6599\u4e2d\u5206\u96e2\u51fa\u4f86\u3002\u63a5\u8457\u67e5\u770b\u4ecb\u9762\u4e0a\u7684\u5230\u9054\u901f\u7387\u3002\u5065\u5eb7\u4f3a\u670d\u5668\u901a\u5e38\u53ea\u6703\u6536\u5230\u4f86\u81ea\u76e3\u63a7\u5de5\u5177\u7684\u96f6\u661f ping\uff0c\u800c\u6d2a\u6cdb\u653b\u64ca\u5247\u6703\u5728\u5e7e\u79d2\u5167\u8b93\u67d0\u500b\u4f86\u6e90\u767c\u4f86\u6578\u767e\u500b\u56de\u61c9\u8acb\u6c42\u3002Tcpdump \u6703\u64f7\u53d6\u6240\u6709\u9019\u4e9b\u8cc7\u6599\u3002\u4f60\u9084\u53ef\u4ee5\u6aa2\u67e5 TTL \u503c\u4ee5\u5224\u65b7\u662f\u5426\u5b58\u5728\u507d\u9020\uff0c\u4e0d\u540c TTL \u51fa\u73fe\u5728\u540c\u4e00\u500b\u4f86\u6e90 IP \u4e0a\uff0c\u901a\u5e38\u8868\u793a\u4f4d\u5740\u662f\u5047\u7684\u3002<\/p>\n<h3>\u7de9\u6162\u9023\u7dda\u5617\u8a66\uff08\u4f4e\u8996\u7a97\u5927\u5c0f SYN \u5c01\u5305\uff09<\/h3>\n<p>\u6709\u4e9b\u653b\u64ca\u8005\u6703\u63a1\u7528\u66f4\u96b1\u853d\u7684\u6383\u63cf\u6280\u8853\u3002\u4ed6\u5011\u9001\u51fa\u8996\u7a97\u5927\u5c0f\u5f88\u4f4e\u7684 SYN \u5c01\u5305\uff0c\u6545\u610f\u653e\u6162\u9023\u7dda\u5efa\u7acb\u904e\u7a0b\u3002\u6a19\u6e96\u6383\u63cf\u5668\u901a\u5e38\u4f7f\u7528\u9810\u8a2d\u8996\u7a97\u503c\uff0c\u800c\u7570\u5e38\u504f\u4f4e\u7684\u8996\u7a97\u503c\u5f80\u5f80\u610f\u5473\u8457\u9019\u662f\u7d93\u904e\u7cbe\u5fc3\u69cb\u9020\u7684\u5c01\u5305\u3002\u653b\u64ca\u8005\u8a66\u5716\u900f\u904e\u66f4\u63a5\u8fd1\u6b63\u5e38\u6d41\u91cf\u7684\u65b9\u5f0f\u4f86\u898f\u907f\u5075\u6e2c\u3002\u6b63\u5e38\u9023\u7dda\u901a\u5e38\u6703\u91dd\u5c0d\u7279\u5b9a\u4f5c\u696d\u7cfb\u7d71\u5448\u73fe\u8f03\u7a69\u5b9a\u7684\u8996\u7a97\u5927\u5c0f\uff0c\u800c tcpdump \u53ef\u4ee5\u5e6b\u52a9\u4f60\u8b58\u5225\u9019\u4e9b\u7570\u5e38\u5617\u8a66\u3002<\/p>\n<p>Tcpdump \u8b93\u9019\u985e\u5206\u6790\u8b8a\u5f97\u76f8\u5c0d\u76f4\u63a5\u3002\u8996\u7a97\u5927\u5c0f\u4f4d\u65bc TCP \u6a19\u982d\u7684\u7b2c 14-15 \u4f4d\u5143\u7d44\u3002\u4f60\u53ef\u4ee5\u57f7\u884c\u4e00\u500b\u904e\u6ffe\u5668\uff0c\u5c08\u9580\u7be9\u9078\u8996\u7a97\u503c\u4f4e\u65bc 1024 \u7684 SYN \u6bb5\u3002Tcpdump \u6703\u986f\u793a\u6bcf\u500b\u53ef\u7591\u5c01\u5305\u7684\u4f86\u6e90\u4f4d\u5740\u548c\u76ee\u6a19\u4f4d\u5740\u3002\u518d\u5c07\u5176\u51fa\u73fe\u983b\u7387\u8207\u57fa\u6e96\u6bd4\u8f03\u3002\u5408\u6cd5\u7528\u6236\u7aef\u5f88\u5c11\u6703\u9001\u51fa\u5982\u6b64\u5c0f\u8996\u7a97\u7684\u5c01\u5305\u3002\u5982\u679c\u540c\u4e00\u500b\u4f86\u6e90\u7a81\u7136\u5927\u91cf\u9001\u51fa\u9019\u985e\u5c01\u5305\uff0c\u5c31\u53ef\u80fd\u610f\u5473\u8457\u7de9\u6162\u6383\u63cf\u3002\u4f60\u53ef\u4ee5\u8a18\u9304\u8a72\u4f86\u6e90\u4f4d\u5740\u4e26\u9032\u884c\u5c01\u9396\uff0c\u540c\u6642\u4fdd\u5b58\u6293\u5305\u8cc7\u6599\u7559\u5f85\u5f8c\u7e8c\u5206\u6790\u3002Tcpdump \u70ba\u4f60\u63d0\u4f9b\u4e86\u63a1\u53d6\u884c\u52d5\u6240\u9700\u7684\u8b49\u64da\u3002<\/p>\n<h2>\u5132\u5b58\u6293\u5305\u4ee5\u7528\u65bc\u4e8b\u5f8c\u6d41\u91cf\u5206\u6790<\/h2>\n<p>\u5373\u6642\u76e3\u63a7\u53ef\u4ee5\u5e6b\u52a9\u4f60\u7b2c\u4e00\u6642\u9593\u767c\u73fe\u554f\u984c\uff0c\u4f46\u7576\u5c01\u5305\u9ad8\u901f\u98db\u904e\u6642\uff0c\u4f60\u7121\u6cd5\u5728\u7576\u4e0b\u7814\u7a76\u6bcf\u4e00\u500b\u7d30\u7bc0\u3002\u5c07\u6293\u5305\u7d50\u679c\u5132\u5b58\u4e0b\u4f86\uff0c\u4fbf\u610f\u5473\u8457\u4f60\u9084\u6709\u7b2c\u4e8c\u6b21\u5206\u6790\u6a5f\u6703\u3002Tcpdump \u900f\u904e\u6a94\u6848\u8f38\u51fa\u652f\u63f4\u9019\u7a2e\u5de5\u4f5c\u65b9\u5f0f\uff0c\u80fd\u5920\u70ba\u9451\u8b58\u5206\u6790\u4fdd\u7559\u539f\u59cb\u8b49\u64da\u3002\u9019\u7a2e\u505a\u6cd5\u5c07\u5373\u6642\u5075\u6e2c\u8207\u6df1\u5165\u8abf\u67e5\u5206\u96e2\u958b\u4f86\u3002<\/p>\n<h3>\u5c07\u6293\u5305\u7d50\u679c\u5beb\u5165\u6a94\u6848<\/h3>\n<p>Tcpdump \u6703\u5c07\u5c01\u5305\u5132\u5b58\u70ba pcap \u683c\u5f0f\u3002\u9019\u4e00\u6a19\u6e96\u683c\u5f0f\u6703\u4fdd\u7559\u539f\u59cb\u6a19\u982d\u548c\u8f09\u8377\uff0c\u5176\u4ed6\u5206\u6790\u5de5\u5177\u4e5f\u53ef\u4ee5\u76f4\u63a5\u8b80\u53d6\uff0c\u7121\u9700\u8f49\u63db\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528 <code>-w<\/code> \u53c3\u6578\u5efa\u7acb pcap \u6a94\u6848\u3002\u4f8b\u5982\uff0c<code>tcpdump -i eth0 -w incident.pcap<\/code> \u6703\u5c07\u6240\u6709\u50b3\u5165\u8cc7\u6599\u5beb\u5165\u6a94\u6848\u3002Tcpdump \u6703\u76f4\u63a5\u5beb\u5165\u78c1\u789f\uff0c\u800c\u4e0d\u662f\u5c07\u7d50\u679c\u8f38\u51fa\u5230\u87a2\u5e55\uff0c\u9019\u6a23\u53ef\u4ee5\u5728\u9ad8\u5c01\u5305\u901f\u7387\u4e0b\u964d\u4f4e\u7cfb\u7d71\u8ca0\u64d4\uff0c\u4e26\u5e6b\u52a9\u4f60\u7684\u4f3a\u670d\u5668\u6301\u7e8c\u64f7\u53d6\u6d41\u91cf\u800c\u4e0d\u8f15\u6613\u907a\u5931\u5c01\u5305\u3002<\/p>\n<p>\u4f60\u9084\u53ef\u4ee5\u4f7f\u7528 <code>-C<\/code> \u53c3\u6578\u63a7\u5236\u6a94\u6848\u5927\u5c0f\u3002Tcpdump \u6703\u5728\u6a94\u6848\u9054\u5230\u6307\u5b9a MB \u5927\u5c0f\u6642\u81ea\u52d5\u5efa\u7acb\u65b0\u6a94\u6848\uff0c\u9019\u6a23\u53ef\u4ee5\u907f\u514d\u55ae\u4e00 pcap \u8cc7\u6599\u96c6\u904e\u5927\u800c\u96e3\u4ee5\u7ba1\u7406\u3002\u4f60\u4e5f\u53ef\u4ee5\u7528 <code>-c<\/code> \u53c3\u6578\u9650\u5236\u6293\u5305\u7e3d\u6578\uff0c\u5230\u9054\u6307\u5b9a\u6578\u91cf\u5f8c tcpdump \u6703\u81ea\u52d5\u505c\u6b62\u3002\u8acb\u70ba\u6293\u5305\u6a94\u6848\u4f7f\u7528\u6709\u610f\u7fa9\u7684\u547d\u540d\u65b9\u5f0f\uff0c\u4f8b\u5982\u5305\u542b\u65e5\u671f\u3001\u6642\u9593\u548c\u4e8b\u4ef6\u985e\u578b\u3002\u9019\u6a23 tcpdump \u5132\u5b58\u4e0b\u4f86\u7684\u8b49\u64da\u6703\u66f4\u6709\u689d\u7406\uff0c\u5f8c\u7e8c\u5728\u8207\u5176\u4ed6\u65e5\u8a8c\u9032\u884c\u95dc\u806f\u5206\u6790\u6642\uff0c\u4e5f\u80fd\u66f4\u5feb\u5b9a\u4f4d\u5230\u7279\u5b9a\u6293\u5305\u3002\u9019\u4e00\u7fd2\u6163\u5728\u4e8b\u5f8c\u5831\u544a\u4e2d\u5c24\u5176\u6709\u50f9\u503c\u3002<\/p>\n<h3>\u70ba Wireshark \u5be9\u67e5\u6e96\u5099\u6293\u5305\u6a94\u6848<\/h3>\n<p>\u547d\u4ee4\u5217\u5206\u6790\u9069\u5408\u5feb\u901f\u6aa2\u67e5\uff0c\u800c\u8907\u96dc\u6d41\u91cf\u5247\u9700\u8981\u66f4\u8c50\u5bcc\u7684\u8996\u89ba\u5316\u8996\u89d2\u3002\u70ba\u6b64\uff0c\u4f60\u53ef\u4ee5\u5728 Wireshark \u4e2d\u958b\u555f\u5132\u5b58\u597d\u7684 pcap \u6a94\u6848\u3002Wireshark \u6703\u81ea\u52d5\u89e3\u78bc\u5354\u5b9a\uff0c\u4e26\u63d0\u4f9b\u5354\u5b9a\u89e3\u78bc\u5668\u8207\u6d41\u5411\u5716\u7b49\u5de5\u5177\uff0c\u8b93\u4f60\u80fd\u66f4\u6e05\u695a\u5730\u770b\u5230\u9023\u7dda\u5efa\u7acb\u8207\u901a\u8a0a\u9806\u5e8f\uff0c\u5f9e\u800c\u4e86\u89e3\u4e00\u53f0\u4e3b\u6a5f\u5982\u4f55\u96a8\u6642\u9593\u8207\u53e6\u4e00\u53f0\u4e3b\u6a5f\u4e92\u52d5\u3002<\/p>\n<p>TLS \u4ea4\u63e1\u7d30\u7bc0\u4e5f\u6703\u66f4\u52a0\u6e05\u695a\u3002Wireshark \u53ef\u4ee5\u89e3\u78bc\u7248\u672c\u3001\u5bc6\u78bc\u5957\u4ef6\u548c\u8b66\u793a\u8a0a\u606f\uff0c\u800c tcpdump \u7121\u6cd5\u4ee5\u6613\u8b80\u65b9\u5f0f\u5448\u73fe\u9019\u4e9b\u5167\u5bb9\u3002\u9019\u6a23\u4f60\u5c31\u80fd\u7372\u5f97\u66f4\u5b8c\u6574\u7684\u7db2\u8def\u6d41\u91cf\u5168\u8c8c\u3002\u532f\u5165 pcap \u6a94\u6848\u4e5f\u5f88\u7c21\u55ae\uff0c\u53ea\u9700\u9ede\u9078 File &gt; Open\u3002\u96a8\u5f8c\u5957\u7528\u986f\u793a\u904e\u6ffe\u5668\uff0c\u5373\u53ef\u9694\u96e2\u7279\u5b9a\u5de5\u4f5c\u968e\u6bb5\u3002\u5132\u5b58\u8207\u8b80\u53d6\u6293\u5305\u6a94\u6848\u540c\u6a23\u6709\u52a9\u65bc\u9577\u671f\u4fdd\u7559\u3002\u4f60\u53ef\u4ee5\u57fa\u65bc\u5408\u898f\u6216\u5718\u968a\u8a13\u7df4\u9700\u6c42\u4fdd\u7559 pcap \u6a94\u6848\uff0c\u8b93\u4e8b\u4ef6\u56de\u61c9\u5718\u968a\u5728\u4e4b\u5f8c\u57fa\u65bc\u540c\u4e00\u4efd\u8b49\u64da\u9032\u884c\u5fa9\u76e4\u3002\u9019\u7a2e\u65b9\u6cd5\u80fd\u5920\u78ba\u4fdd\u7d44\u7e54\u5167\u90e8\u5206\u6790\u53e3\u5f91\u4e00\u81f4\u3002\u8acb\u7d93\u5e38\u7df4\u7fd2\u4f7f\u7528 tcpdump\uff0c\u4ee5\u4e0d\u65b7\u63d0\u5347\u6280\u80fd\u3002<\/p>\n<div class=\"qc-divider-wrapper\">\n<div class=\"qc-divider\" style=\"border-top-style: solid;width: 100%\"><\/div>\n<\/div>\n<p>Tcpdump \u672c\u8eab\u975e\u5e38\u8f15\u91cf\u3002\u4e00\u65e6\u4f60\u77e5\u9053\u8a72\u91cd\u9ede\u95dc\u6ce8\u4ec0\u9ebc\u2014\u2014\u65d7\u6a19\u3001\u901f\u7387\u548c\u4f86\u6e90\u2014\u2014\u5b83\u5c31\u80fd\u5e6b\u52a9\u4f60\u767c\u73fe\u7570\u5e38\u884c\u70ba\u3002\u5efa\u8b70\u5148\u5728\u6e2c\u8a66\u74b0\u5883\u4e2d\u7df4\u7fd2\u3002\u5148\u5efa\u7acb\u57fa\u6e96\uff0c\u518d\u5c07\u65b0\u7684\u6293\u5305\u7d50\u679c\u8207\u4e4b\u6bd4\u8f03\u3002\u9019\u6a23\u7684\u7fd2\u6163\u6703\u4e0d\u65b7\u63d0\u5347\u4f60\u6392\u67e5\u771f\u5be6\u554f\u984c\u6642\u7684\u654f\u92b3\u5ea6\u3002<\/p>\n<p>\u7136\u5f8c\u7e7c\u7e8c\u6df1\u5165\u3002\u4f60\u53ef\u4ee5\u900f\u904e\u6307\u4ee4\u78bc\u5be6\u73fe\u81ea\u52d5\u8490\u96c6\uff0c\u628a\u9019\u4e9b\u6a94\u6848\u9001\u5230 SIEM\uff0c\u6216\u8005\u5617\u8a66\u4f7f\u7528 Bro \u8207 Zeek \u505a\u66f4\u6df1\u5c64\u7684\u5075\u6e2c\u3002\u6bcf\u524d\u9032\u4e00\u6b65\uff0c\u90fd\u662f\u5728\u628a\u539f\u59cb\u5c01\u5305\u8f49\u5316\u70ba\u53ef\u57f7\u884c\u7684\u7b54\u6848\u3002\u4eca\u5929\u5c31\u958b\u59cb\u6293\u5305\u5427\u2014\u2014\u4f60\u7684\u7db2\u8def\u65e5\u8a8c\u88e1\uff0c\u4e5f\u8a31\u5df2\u7d93\u85cf\u8457\u6545\u969c\u7684\u7b2c\u4e00\u9053\u5fb5\u5146\u3002<\/p>\n<h2>\u5e38\u898b\u554f\u984c<\/h2>\n<h3>\u6211\u600e\u9ebc\u5224\u65b7\u4f3a\u670d\u5668\u662f\u5426\u6b63\u5728\u906d\u53d7 SYN \u6d2a\u6cdb\u653b\u64ca\uff1f<\/h3>\n<p>\u4f60\u6703\u770b\u5230\u5927\u91cf SYN \u5c01\u5305\u5feb\u901f\u6e67\u5165\uff0c\u537b\u6c92\u6709\u5c0d\u61c9\u7684 ACK \u56de\u61c9\u3002\u57f7\u884c <code>tcpdump -i eth0 -l \"tcp[13] == 0x02\"<\/code> \u4e26\u89c0\u5bdf\u901f\u7387\u3002\u5982\u679c\u67d0\u4e00\u4f86\u6e90\u6bcf\u79d2\u9054\u5230\u6578\u767e\u500b\uff0c\u5c31\u53ef\u80fd\u662f\u5728\u653b\u64ca\u3002\u5c07\u9019\u7a2e\u8868\u73fe\u8207\u4f60\u7684\u57fa\u6e96\u6293\u5305\u7d50\u679c\u9032\u884c\u6bd4\u8f03\u3002<\/p>\n<h3>Tcpdump \u80fd\u986f\u793a DNS \u653e\u5927\u653b\u64ca\u662f\u5426\u6b63\u5728\u767c\u751f\u55ce\uff1f<\/h3>\n<p>\u53ef\u4ee5\u3002\u904e\u6ffe UDP 53 \u9023\u63a5\u57e0\u6d41\u91cf\uff0c\u4e26\u95dc\u6ce8\u56de\u61c9\u5927\u5c0f\u3002\u6b63\u5e38\u56de\u61c9\u901a\u5e38\u8f03\u5c0f\uff0c\u800c\u67d0\u500b\u89e3\u6790\u5668\u6301\u7e8c\u5411\u55ae\u4e00\u76ee\u6a19\u9001\u51fa\u8d85\u5927\u56de\u61c9\uff0c\u5247\u8868\u793a\u5b58\u5728\u6feb\u7528\u884c\u70ba\u3002Tcpdump \u6703\u986f\u793a\u6bcf\u500b\u5927\u56de\u61c9\u7684\u4f86\u6e90\u4f4d\u5740\u3002<\/p>\n<h3>\u70ba\u4ec0\u9ebc pcap \u6a94\u6848\u5728\u4e8b\u5f8c\u5206\u6790\u4e2d\u5f88\u6709\u7528\uff1f<\/h3>\n<p>Pcap \u6a94\u6848\u4fdd\u7559\u4e86\u539f\u59cb\u6a19\u982d\u548c\u8f09\u8377\u3002\u4f60\u4e4b\u5f8c\u53ef\u4ee5\u5728 Wireshark \u4e2d\u958b\u555f\u5b83\uff0c\u67e5\u770b\u5354\u5b9a\u89e3\u78bc\u7d50\u679c\u548c\u6d41\u5411\u5716\u3002\u5718\u968a\u6210\u54e1\u4e5f\u80fd\u57fa\u65bc\u540c\u4e00\u4efd\u8b49\u64da\u9032\u884c\u5fa9\u76e4\u3002\u5efa\u8b70\u6309\u7167\u65e5\u671f\u548c\u4e8b\u4ef6\u985e\u578b\u5c0d pcap \u6a94\u6848\u9032\u884c\u5206\u985e\u6574\u7406\uff0c\u4ee5\u4fbf\u65e5\u5f8c\u5feb\u901f\u6aa2\u7d22\u3002<\/p>\n<h3>\u70ba\u4ec0\u9ebc\u653b\u64ca\u8005\u6703\u9001\u51fa\u4f4e\u8996\u7a97\u5927\u5c0f\u7684 SYN \u5c01\u5305\uff1f<\/h3>\n<p>\u8f03\u4f4e\u7684\u8996\u7a97\u5927\u5c0f\u6703\u6545\u610f\u62d6\u6162\u9023\u7dda\u4ea4\u63e1\u904e\u7a0b\u3002\u6a19\u6e96\u6383\u63cf\u5668\u901a\u5e38\u4f7f\u7528\u9810\u8a2d\u503c\uff0c\u56e0\u6b64\u9019\u985e\u7570\u5e38\u504f\u4f4e\u7684\u8996\u7a97\u503c\u5f80\u5f80\u4ee3\u8868\u66f4\u96b1\u853d\u7684\u6383\u63cf\u884c\u70ba\u3002\u5982\u679c\u540c\u4e00\u500b\u4f86\u6e90\u7a81\u7136\u5927\u91cf\u9001\u51fa\u9019\u7a2e\u69cb\u9020\u904e\u7684\u5c01\u5305\uff0c\u5c31\u5f88\u53ef\u80fd\u662f\u4e00\u6b21\u96b1\u853d\u6383\u63cf\u3002\u4f60\u53ef\u4ee5\u900f\u904e\u904e\u6ffe\u8f03\u5c0f\u8996\u7a97\u7684 SYN \u6bb5\u4f86\u767c\u73fe\u5b83\u5011\u3002<\/p>\n<h3>\u6211\u61c9\u8a72\u591a\u4e45\u6293\u4e00\u6b21\u6d41\u91cf\uff0c\u624d\u80fd\u5efa\u7acb\u53ef\u9760\u7684\u57fa\u6e96\uff1f<\/h3>\n<p>\u61c9\u7576\u5728\u65e5\u5e38\u696d\u52d9\u6b63\u5e38\u904b\u4f5c\u671f\u9593\uff0c\u9023\u7e8c\u6578\u5929\u9032\u884c\u6293\u5305\u3002\u7b2c\u4e00\u6b21\u63a1\u6a23\u6642\u76e1\u91cf\u907f\u958b\u5c16\u5cf0\u671f\u3002\u7a69\u5b9a\u7684\u5c01\u5305\u901f\u7387\u548c\u53ef\u9810\u6e2c\u7684\u4f86\u6e90\u4f4d\u5740\u6703\u69cb\u6210\u4f60\u7684\u53c3\u8003\u57fa\u6e96\u3002\u4e4b\u5f8c\u4efb\u4f55\u504f\u96e2\u8a72\u6a21\u5f0f\u7684\u73fe\u8c61\uff0c\u90fd\u503c\u5f97\u4f60\u9032\u4e00\u6b65\u8abf\u67e5\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4f60\u7684\u4f3a\u670d\u5668\u8b8a\u6162\u4e86\u3002\u4f60\u57f7\u884c tcpdump\uff0c\u770b\u5230\u5927\u91cf SYN \u5c01\u5305\u6e67\u5165\u3002\u9019\u5c31\u662f\u7570\u5e38\u73fe\u8c61\u3002Tcpdump \u662f\u4e00\u6b3e\u547d [&#8230;]<\/p>\n<p><a class=\"btn btn-secondary understrap-read-more-link\" href=\"https:\/\/www.varidata.com\/zh-tw\/knowledge-tc\/how-to-spot-abnormal-traffic-on-a-server-using-tcpdump\/\">Read More&#8230;<\/a><\/p>\n","protected":false},"author":12,"featured_media":36339,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[268],"tags":[],"class_list":["post-36342","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-knowledge-tc"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.2 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>\u5982\u4f55\u4f7f\u7528 tcpdump \u767c\u73fe\u4f3a\u670d\u5668\u4e0a\u7684\u7570\u5e38\u6d41\u91cf<\/title>\n<meta name=\"description\" content=\"\u4f7f\u7528 tcpdump 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