Fail2ban 防止暴力破解centos服务器的SSH或者FTP账户

第一次将CentOS服务器配上外网可访问的网络配置，发现每次通过外网地址登陆ssh，链接时间长，同时爆出以下信息，显示从上一次登陆成功到本次登陆成功，中间有3896次尝试登陆root账户失败的情况。【说明服务器被攻击了】

Last failed login: Sat Mar 19 09:34:18 CST 2016 from 222.186.15.82 on ssh:notty

There were 3896 failed login attempts since the last successful login.

Last login: Sat Mar 19 09:12:33 2016 from 117.114.129.166

基于CentOS 6或者7版本的系统，我们可以安装Fail2ban工具来阻止一定的暴力破解SSH或者FTP账户问题，也许不能足够的解决问题，但至少可以解决一般的问题。

第一、Fail2ban安装

A - CentOS 6

rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
yum install fail2ban

B - CentOS 7

rpm -Uvh http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-2.noarch.rpm
yum install fail2ban

[说明]执行以上第一句，若找不到是因为版本更新后，旧版本就删除了。所有打开“http://dl.fedoraproject.org/pub/epel/7/x86_64/e/”找找相应的rpm

第二、Fail2ban设置

（1）各配置文件用途

/etc/fail2ban/action.d            #动作文件夹，内含默认文件。iptables以及mail等动作配置
/etc/fail2ban/fail2ban.conf        #定义了fai2ban日志级别、日志位置及sock文件位置
/etc/fail2ban/filter.d            #条件文件夹，内含默认文件。过滤日志关键内容设置
/etc/fail2ban/jail.conf            #主要配置文件，模块化。主要设置启用ban动作的服务及动作阀值
/etc/rc.d/init.d/fail2ban          #启动脚本文件

（2）、fail2ban.conf一般不用改，再确认以下几项：

vi /etc/fail2ban/fail2ban.conf
[Definition] 
loglevel =3 
logtarget = SYSLOG  #我们需要做的就是把这行改成/var/log/fail2ban.log，方便用来记录日志信息
socket =/var/run/fail2ban/fail2ban.sock

（3）编辑/etc/fail2b    an/jail.conf文件，修改或添加防攻击规则。(后面有规则的举例)

【特别说明】 

   （1）“[INCLUDES]”以前的不要动（都是注释），否则fail2ban服务就无法启动。可以用命令来检查语法错误 #fail2ban-client -v -v start

（2）“[DEFAULT]”里的 “enabled = false”不能改为true，否则fail2ban服务就无法启动。

centos Job for fail2ban.service failed because the control process exited with error code. See "systemctl status fail2ban.service" and "journalctl -xe" for details

第三、重启Fail2ban服务，立即生效。

systemctl restart fail2ban.service

第四、防攻击规则，举例

关键词

[DEFAULT]               #全局设置
ignoreip = 127.0.0.1       #忽略的IP列表,不受设置限制，多个以空格隔开
bantime  = 600             #屏蔽时间，单位：秒
findtime  = 600             #这个时间段内超过规定次数会被ban掉
maxretry = 3                #最大尝试次数
backend = auto            #日志修改检测机制（gamin、polling和auto这三种）
 
[sshd]                   #单个服务检查设置，如设置bantime、findtime、maxretry和全局冲突，服务优先级大于全局设置。
enabled  = true             #是否激活此项（true/false）
filter   = sshd              #过滤规则filter的名字，对应filter.d目录下的sshd.conf
action   = iptables[name=SSH, port=ssh, protocol=tcp]#动作的相关参数，对应action.d/iptables.conf文件
logpath  = /var/log/secure         #检测的日志文件path
bantime  = 3600
findtime  = 300
maxretry = 3

防攻击规则参见：

(1)SSH防攻击规则

[ssh-iptables]
enabled  = true
filter   = sshd
action   = iptables[name=SSH, port=ssh, protocol=tcp]
           sendmail-whois[name=SSH, dest=root, sender=[e-mail], sendername="Fail2Ban"]
logpath  = /var/log/secure
maxretry = 5
[ssh-ddos]
enabled = true
filter  = sshd-ddos
action  = iptables[name=ssh-ddos, port=ssh,sftp protocol=tcp,udp]
logpath  = /var/log/messages
maxretry = 2
[osx-ssh-ipfw]
enabled  = true
filter   = sshd
action   = osx-ipfw
logpath  = /var/log/secure.log
maxretry = 5
[ssh-apf]
enabled = true
filter  = sshd
action  = apf[name=SSH]
logpath = /var/log/secure
maxretry = 5
[osx-ssh-afctl]
enabled  = true
filter   = sshd
action   = osx-afctl[bantime=600]
logpath  = /var/log/secure.log
maxretry = 5
[selinux-ssh]
enabled = true
filter  = selinux-ssh
action  = iptables[name=SELINUX-SSH, port=ssh, protocol=tcp]
logpath  = /var/log/audit/audit.log
maxretry = 5

(2)proftp防攻击规则

 

[proftpd-iptables]
enabled  = true
filter   = proftpd
action   = iptables[name=ProFTPD, port=ftp, protocol=tcp]
           sendmail-whois[name=ProFTPD, dest=[e-mail]]
logpath  = /var/log/proftpd/proftpd.log
maxretry = 6

(3)邮件防攻击规则

[sasl-iptables]
enabled  = true
filter   = postfix-sasl
backend  = polling
action   = iptables[name=sasl, port=smtp, protocol=tcp]
           sendmail-whois[name=sasl, dest=[e-mail]]
logpath  = /var/log/mail.log
[dovecot]
enabled = true
filter  = dovecot
action  = iptables-multiport[name=dovecot, port="pop3,pop3s,imap,imaps,submission,smtps,sieve", protocol=tcp]
logpath = /var/log/mail.log
[dovecot-auth]
enabled = true
filter  = dovecot
action  = iptables-multiport[name=dovecot-auth, port="pop3,pop3s,imap,imaps,submission,smtps,sieve", protocol=tcp]
logpath = /var/log/secure
[perdition]
enabled = true
filter  = perdition
action  = iptables-multiport[name=perdition,port="110,143,993,995"]
logpath = /var/log/maillog
 
[uwimap-auth]
enabled = true
filter  = uwimap-auth
action  = iptables-multiport[name=uwimap-auth,port="110,143,993,995"]
logpath = /var/log/maillog

(4)apache防攻击规则

[apache-tcpwrapper]
enabled  = true
filter  = apache-auth
action   = hostsdeny
logpath  = /var/log/httpd/error_log
maxretry = 6
[apache-badbots]
enabled  = true
filter   = apache-badbots
action   = iptables-multiport[name=BadBots, port="http,https"]
           sendmail-buffered[name=BadBots, lines=5, dest=[e-mail]]
logpath  = /var/log/httpd/access_log
bantime  = 172800
maxretry = 1
[apache-shorewall]
enabled  = true
filter   = apache-noscript
action   = shorewall
           sendmail[name=Postfix, dest=[e-mail]]
logpath  = /var/log/httpd/error_log

(5)nginx防攻击规则

[nginx-http-auth]
enabled = true
filter  = nginx-http-auth
action  = iptables-multiport[name=nginx-http-auth,port="80,443"]
logpath = /var/log/nginx/error.log

(6)lighttpd防规击规则

[suhosin]
enabled  = true
filter   = suhosin
action   = iptables-multiport[name=suhosin, port="http,https"]
# adapt the following two items as needed
logpath  = /var/log/lighttpd/error.log
maxretry = 2
[lighttpd-auth]
enabled  = true
filter   = lighttpd-auth
action   = iptables-multiport[name=lighttpd-auth, port="http,https"]
# adapt the following two items as needed
logpath  = /var/log/lighttpd/error.log
maxretry = 2

(7)vsftpd防攻击规则

[vsftpd-notification]
enabled  = true
filter   = vsftpd
action   = sendmail-whois[name=VSFTPD, dest=[e-mail]]
logpath  = /var/log/vsftpd.log
maxretry = 5
bantime  = 1800
[vsftpd-iptables]
enabled  = true
filter   = vsftpd
action   = iptables[name=VSFTPD, port=ftp, protocol=tcp]
           sendmail-whois[name=VSFTPD, dest=[e-mail]]
logpath  = /var/log/vsftpd.log
maxretry = 5
bantime  = 1800

(8)pure-ftpd防攻击规则

[pure-ftpd]
enabled  = true
filter   = pure-ftpd
action   = iptables[name=pure-ftpd, port=ftp, protocol=tcp]
logpath  = /var/log/pureftpd.log
maxretry = 2
bantime  = 86400

(9)mysql防攻击规则

[mysqld-iptables]
enabled  = true
filter   = mysqld-auth
action   = iptables[name=mysql, port=3306, protocol=tcp]
           sendmail-whois[name=MySQL, dest=root, sender=[e-mail]]
logpath  = /var/log/mysqld.log
maxretry = 5

(10)apache phpmyadmin防攻击规则

[apache-phpmyadmin]
enabled  = true
filter   = apache-phpmyadmin
action  = iptables[name=phpmyadmin, port=http,https protocol=tcp]
logpath  = /var/log/httpd/error_log
maxretry = 3
# /etc/fail2ban/filter.d/apache-phpmyadmin.conf
将以下内容粘贴到apache-phpmyadmin.conf里保存即可以创建一个apache-phpmyadmin.conf文件.
# Fail2Ban configuration file
#
# Bans bots scanning for non-existing phpMyAdmin installations on your webhost.
#
# Author: Gina Haeussge
#
[Definition]
docroot = /var/www
badadmin = PMA|phpmyadmin|myadmin|mysql|mysqladmin|sqladmin|mypma|admin|xampp|mysqldb|mydb|db|pmadb|phpmyadmin1|phpmyadmin2
# Option:  failregex
# Notes.:  Regexp to match often probed and not available phpmyadmin paths.
# Values:  TEXT
#
failregex = [[]client []] File does not exist: %(docroot)s/(?:%(badadmin)s)
# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT
#
ignoreregex =
# service fail2ban restart

第五、新建防攻击规则

 以nginx为例，具体设置方法如下：

（1）首先在jail.conf文件下追加以下内容：

[nginx]    ;规则名字
enabled = true ;是否户用
port = http,https ;监控端口
filter = nginx    ;需要过滤匹配规则
logpath = /var/log/nginx/access_log; 日志路径
findtime =60    ;检测周期 单位秒 以下一样
bantime =300    ;iptable封禁IP时间
maxretry =10    ;最大尝试次数
action = iptables[name=nginx, port=http, protocal=tcp] ;发现暴力破解采取iptalbes封禁IP的措施
         sendmail[name=nginx, dest=[e-mail]]    ;发现暴力破解后采取sendmail发送邮件的措施，需要注意的是：iptables和sendmail必须对齐，要不然会发生错误；不要问我为什么会知道。

（2）然后创建 /etc/fail2ban/filter.d/nginx.conf文件，并添加以下内容：

[Definition]
failregex =<HOST>.*-.*-.*POST.*/login_check.do.* HTTP\/1.*http://test.com.*$ ;需要匹配日志发现攻击行为的正则,<HOST>为fail2ban内置变量匹配IP，不可修改
ignoreregex =    ;需要忽略的正则

（3）systemctl restart fail2ban 立即生效。

第六、查询限制列表   iptables -L --line-numbers

红色的表示已经由fail2ban限制了。

[root@bogon ~]#  iptables -L --line-numbers
Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination         
1    f2b-SSH    tcp  --  anywhere             anywhere             tcp dpt:ssh
2    f2b-SSH    tcp  --  anywhere             anywhere             tcp dpt:ssh
3    ACCEPT     udp  --  anywhere             anywhere             udp dpt:domain
4    ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:domain
5    ACCEPT     udp  --  anywhere             anywhere             udp dpt:bootps
6    ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:bootps
7    ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED
8    ACCEPT     all  --  anywhere             anywhere            
9    INPUT_direct  all  --  anywhere             anywhere            
10   INPUT_ZONES_SOURCE  all  --  anywhere             anywhere            
11   INPUT_ZONES  all  --  anywhere             anywhere            
12   ACCEPT     icmp --  anywhere             anywhere            
13   REJECT     all  --  anywhere             anywhere             reject-with icmp-host-prohibited
 
Chain f2b-SSH (2 references)
num  target     prot opt source               destination         
1    REJECT     all  --  58.218.211.38        anywhere             reject-with icmp-port-unreachable
2    RETURN     all  --  anywhere             anywhere            
You have new mail in /var/spool/mail/root

第七、解除fail2ban绑定的IP

查询限制列表

# iptables -L --line-numbers
Chain f2b-SSH (2 references)
num  target     prot opt source               destination         
1    REJECT     all  --  58.218.211.38        anywhere             reject-with icmp-port-unreachable
2    RETURN     all  --  anywhere             anywhere     

解除限制

# iptables -D f2b-SSH 1
上面是解除第一个拒绝的IP

第八、统计登陆失败的IP

[root@bogon ~]# find /var/log -name 'secure*' -type f | while read line;do awk '/Failed/{print $(NF-3)}' $line;done | awk '{a[$0]++}END{for (j in a) if(a[j] > 20) print j"="a[j]}' | sort -n -t'=' -k 2
202.99.172.155=24
123.126.110.69=25
222.74.228.85=136
5.189.139.232=557
222.178.229.67=1005
222.186.15.82=1883
59.63.188.44=6748
58.218.211.38=6752
[root@bogon ~]# 

有上面几个IP尝试通过不同的端口攻击我的服务器

另外给root账户设置24位随机密码：

rootpass=`date +%s | sha256sum | base64 | head -c 24` && echo root:$rootpass  | chpasswd && echo $rootpass