一、fail2ban简介
fail2ban可以监视你的系统日志，然后匹配日志的错误信息（正则式匹配）执行相应的屏蔽动作（一般情况下是防火墙），而且可以发送e-mail通知系统管理员，是不是很好、很实用、很强大！
二、简单来介绍一下fail2ban的功能和特性
1、支持大量服务。如sshd,apache,qmail,proftpd,sasl等等
2、支持多种动作。如iptables,tcp-wrapper,shorewall(iptables第三方工具),mail notifications(邮件通知)等等。
3、在logpath选项中支持通配符
4、需要Gamin支持(注：Gamin是用于监视文件和目录是否更改的服务工具)
5、需要安装python,iptables,tcp-wrapper,shorewall,Gamin。如果想要发邮件，那必需安装postfix/sendmail
三、fail2ban安装与配置操作实例
为了在CentOS 或 RHEL上安装fail2ban,首先设置EPEL仓库
根据你的CentOS 版本来选择正确的下载地址。
下载EPEL 的rpm 安装包CentOS 版本所对应的EPEL 的版本
wget
rpm -ivh epel-release-6-8.noarch.rpm
安装好EPEL 源后，用yum 命令来检查是否添加到源列表
yum repolist
现在来试一下从EPEL 获取软件包
yum install fail2ban
service fail2ban restart
检查是否成功运行
fail2ban-client ping
#Server replied: pong
vi/etc/fail2ban/jail.conf
SSH防攻击规则
. 代码如下:
[ssh-iptables]
enabled = true
filter = sshd
action = iptables[name=SSH, port=ssh, protocol=tcp]
sendmail-whois[name=SSH, dest=root, sender=fail2ban@example.com, 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
proftp防攻击规则
. 代码如下:
[proftpd-iptables]
enabled = true
filter = proftpd
action = iptables[name=ProFTPD, port=ftp, protocol=tcp]
sendmail-whois[name=ProFTPD, dest=you@example.com]
logpath = /var/log/proftpd/proftpd.log
maxretry = 6
邮件防攻击规则
. 代码如下:
[sasl-iptables]
enabled = true
filter = postfix-sasl
backend = polling
action = iptables[name=sasl, port=smtp, protocol=tcp]
sendmail-whois[name=sasl, dest=you@example.com]
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
apache防攻击规则
. 代码如下:
[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=you@example.com]
logpath = /var/log/httpd/access_log
bantime = 172800
maxretry = 1
[apache-shorewall]
enabled = true
filter = apache-noscript
action = shorewall
sendmail[name=Postfix, dest=you@example.com]
logpath = /var/log/httpd/error_log
nginx防攻击规则
. 代码如下:
[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
lighttpd防规击规则
. 代码如下:
[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
vsftpd防攻击规则
. 代码如下:
[vsftpd-notification]
enabled = true
filter = vsftpd
action = sendmail-whois[name=VSFTPD, dest=you@example.com]
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=you@example.com]
logpath = /var/log/vsftpd.log
maxretry = 5
bantime = 1800
pure-ftpd防攻击规则
. 代码如下:
[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
mysql防攻击规则
. 代码如下:
[mysqld-iptables]
enabled = true
filter = mysqld-auth
action = iptables[name=mysql, port=3306, protocol=tcp]
sendmail-whois[name=MySQL, dest=root, sender=fail2ban@example.com]
logpath = /var/log/mysqld.log
maxretry = 5
其主要配置文件fail2ban/jail.conf
vi /etc/fail2ban/jail.conf
[DEFAULT] #全局设置
ignoreip = 127.0.0.1 #忽略的IP列表,不受设置限制
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
service fail2ban start 启动服务
fail2ban的“ssh-iptables”监狱使用iptables来阻塞问题IP地址，可以通过以下方式来检测当前iptables来验证禁止规则。
iptables --list -n
从fail2ban中解锁某个IP地址，你可以使用iptables命令：
iptables -D fail2ban-SSH -s 202.98.172.11 -j DROP
为了检验fail2ban状态（会显示出当前活动的监狱列表）：
fail2ban-client status
为了检验一个特定监狱的状态（例如ssh-iptables):
fail2ban-client status ssh-iptables
注意，如果你停止了Fail2ban 服务，那么所有的IP地址都会被解锁。当你重启 Fail2ban，它会从/etc/log/secure(或 /var/log/auth.log)中找到异常的IP地址列表.
如果这些异常地址的发生时间仍然在禁止时间内，那么Fail2ban会重新将这些IP地址禁止。
设置 Fail2ban 自动启动
chkconfig fail2ban on
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