CC攻击很容易发起，并且几乎不需要成本，导致现在的CC攻击越来越多。大部分搞CC攻击的人，都是用在网上下载的工具，这些工具很少去伪造特征，所以会留下一些痕迹。使用下面的命令，可以分析下是否在被CC攻击。第一条命令：
tcpdump -s0 -A -n -i any | grep -o -E (GET|POST|HEAD) .*
正常的输出结果类似于这样POST /ajax/validator.php HTTP/1.1POST /api_redirect.php HTTP/1.1GET /team/57085.html HTTP/1.1POST /order/pay.php HTTP/1.1GET /static/goodsimg/20140324/1_47.jpg HTTP/1.1GET /static/theme/qq/css/index.css HTTP/1.1GET /static/js/index.js HTTP/1.1GET /static/js/customize.js HTTP/1.1GET /ajax/loginjs.php?type=topbar HTTP/1.1GET /static/js/jquery.js HTTP/1.1GET /ajax/load_team_time.php?team_id=57085 HTTP/1.1GET /static/theme/qq/css/index.css HTTP/1.1GET /static/js/lazyload/jquery.lazyload.min.js HTTP/1.1GET /static/js/MSIE.PNG.js HTTP/1.1GET /static/js/index.js HTTP/1.1GET /static/js/customize.js HTTP/1.1GET /ajax/loginjs.php?type=topbar HTTP/1.1GET /static/theme/qq/css/i/logo.jpg HTTP/1.1GET /static/theme/qq/css/i/logos.png HTTP/1.1GET /static/theme/qq/css/i/hot.gif HTTP/1.1GET /static/theme/qq/css/i/brand.gif HTTP/1.1GET /static/theme/qq/css/i/new.gif HTTP/1.1GET /static/js/jquery.js HTTP/1.1GET /static/theme/qq/css/i/logo.jpg HTTP/1.1正常命令结果以静态文件为主，比如css,js,各种图片。如果是被攻击，会出现大量固定的地址，比如攻击的是首页，会有大量的GET / HTTP/1.1，或者有一定特征的地址，比如攻击的如果是Discuz论坛，那么可能会出现大量的/thread-随机数字-1-1.html这样的地址。第二条命令：
tcpdump -s0 -A -n -i any | grep^User-Agent
输出结果类似于下面：User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727; 360space)User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727; 360space)User-Agent: Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727; InfoPath.2)User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)这个是查看客户端的useragent，正常的结果中，是各种各样的useragent。大多数攻击使用的是固定的useragent，也就是会看到同一个useragent在刷屏。随机的useragent只见过一次，但是给搞成了类似于这样axd5m8usy，还是可以分辨出来。第三条命令：
tcpdump -s0 -A -n -i any | grep ^Host
如果机器上的网站太多，可以用上面的命令找出是哪个网站在被大量请求输出结果类似于下面这样Host:www.server110.comHost:www.server110.comHost:www.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost:www.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost:www.server110.comHost:www.server110.comHost: upload.server110.comHost: upload.server110.comHost: upload.server110.comHost:www.server110.comHost: upload.server110.comHost: upload.server110.comHost:www.server110.com一般系统不会默认安装tcpdump命令centos安装方法：yum install -y tcpdumpdebian/ubuntu安装方法：apt-get install -y tcpdump很多小白用户不懂得如何设置日志，查看日志，使用上面的命令则简单的多，复制到命令行上运行即可。