CentOS下安装配置pptpd VPN

安装PPP

yum -y install ppp

 

到rpmfind.net下载pptpd rpm包或者到sf下载源码包自己编译,懒人当然是下载rpm包了

http://sourceforge.net/projects/poptop/files/

ftp://rpmfind.net/linux/epel/6/x86_64/pptpd-1.4.0-3.el6.x86_64.rpm

rpm -ivh pptpd-1.4.0-3.el6.x86_64.rpm

配置很简单,/etc/pptpd.conf里面,设置一下IP

localip 10.8.0.1

remoteip 10.8.0.2-254

/etc/ppp/chap-secrets 里面设置用户账户,格式如下

第一个test是用户,第二个test是密码 ,*表示任意ip

 

配置文件/etc/sysctl.conf
vi /etc/sysctl.conf
修改以下内容开启ip转发:
net.ipv4.ip_forward = 1
保存、退出后执行:
sysctl -p

因为没有公网地址分配给客户端,所以要使用iptables做nat转发让客户端可以上网

iptables -A POSTROUTING -t nat -s 10.8.0.1/24 -o eth0 -j MASQUERADE

 

好了,启动pptpd,用自己的电脑新建一个vpn连接过去试试吧

Linux主机简单判断CC攻击的命令

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/1.1
POST /api_redirect.php HTTP/1.1
GET /team/57085.html HTTP/1.1
POST /order/pay.php HTTP/1.1
GET /static/goodsimg/20140324/1_47.jpg HTTP/1.1
GET /static/theme/qq/css/index.css HTTP/1.1
GET /static/js/index.js HTTP/1.1
GET /static/js/customize.js HTTP/1.1
GET /ajax/loginjs.php?type=topbar& HTTP/1.1
GET /static/js/jquery.js HTTP/1.1
GET /ajax/load_team_time.php?team_id=57085 HTTP/1.1
GET /static/theme/qq/css/index.css HTTP/1.1
GET /static/js/lazyload/jquery.lazyload.min.js HTTP/1.1
GET /static/js/MSIE.PNG.js HTTP/1.1
GET /static/js/index.js HTTP/1.1
GET /static/js/customize.js HTTP/1.1
GET /ajax/loginjs.php?type=topbar& HTTP/1.1
GET /static/theme/qq/css/i/logo.jpg HTTP/1.1
GET /static/theme/qq/css/i/logos.png HTTP/1.1
GET /static/theme/qq/css/i/hot.gif HTTP/1.1
GET /static/theme/qq/css/i/brand.gif HTTP/1.1
GET /static/theme/qq/css/i/new.gif HTTP/1.1
GET /static/js/jquery.js HTTP/1.1
GET /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/537.1
User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1
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/537.1
User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1
User-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/537.1
User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1
User-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/537.1
User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1
User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1
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 (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/537.1
User-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.com
Host: www.server110.com
Host: www.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: www.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: www.server110.com
Host: www.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: www.server110.com
Host: upload.server110.com
Host: upload.server110.com
Host: www.server110.com

一般系统不会默认安装tcpdump命令
centos安装方法:yum install -y tcpdump
debian/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。


http://www.server110.com/linux_sec/201406/10670.html