fail2ban配置与说明

1.安装比较简单

wget http://cdnetworks-kr-2.dl.sourceforge.net/project/fail2ban/fail2ban-stable/fail2ban-0.8.4/fail2ban-0.8.4.tar.bz2

tar xvfj fail2ban-0.8.4.tar.bz2
cd fail2ban-0.8.4
python setup.py install
cd files
cp ./redhat-initd /etc/init.d/fail2ban
chkconfig --add fail2ban
service fail2ban start

2.设定fail2ban服务

fail2ban 的设定档在这里

/etc/fail2ban

fail2ban.conf 日志设定文档
jail.conf 阻挡设定文档

/etc/fail2ban/filter.d 具体阻挡内容设定目录

3.实施保护

总体配置：

ignoreip = 127.0.0.1　
#此ip或者ip段不会被封锁
bantime = 60000
#出错一次封锁的时间
findtime = 600
#在多少秒内出现规定次数就开始工作
maxretry = 2
#最大尝试次数，下面的次数可以覆盖这里的次数

1. 保护 SSH 拦截

先看看fail2ban是如何拦截的？

cat /etc/fail2ban/filter.d/sshd.conf

failregex = ^%(__prefix_line)s(?:error: PAM: )?Authentication failure for .* from <HOST>\s*$
            ^%(__prefix_line)sFailed [-/\w]+ for .* from <HOST>(?: port \d*)?(?: ssh\d*)?$
            ^%(__prefix_line)sROOT LOGIN REFUSED.* FROM <HOST>\s*$
            ^%(__prefix_line)s[iI](?:llegal|nvalid) user .* from <HOST>\s*$
            ^%(__prefix_line)sUser \S+ from <HOST> not allowed because not listed in AllowUsers$
            ^%(__prefix_line)sauthentication failure; logname=\S* uid=\S* euid=\S* tty=\S* ruser=\S* rhost=<HOST>(?:\s+user=.*)?\s*$
            ^%(__prefix_line)srefused connect from \S+ $<HOST>$\s*$
            ^%(__prefix_line)sAddress <HOST> .* POSSIBLE BREAK-IN ATTEMPT\s*$

fail2ban 使用了正则表达式找出:

Authentication failure/authentication failure

ROOT LOGIN REFUSED

refused connect from

POSSIBLE BREAK-IN ATTEMPT

not allowed because not listed in AllowUsers

以上的状况，可以根据你实际要求删减. 其中<HOST> 为建立连接的IP

开启 SSH 拦截

vi /etc/fail2ban/jail.conf

[ssh-iptables]

enabled = true
filter   = sshd
action   = iptables[name=SSH, port=ssh, protocol=tcp]
           sendmail-whois[name=SSH, dest=收件者电邮地址, sender=寄件者电邮地址]
logpath = /var/log/secure
maxretry = 3
findtime = 300
bantime = 86400

fail2ban 会按照你的要求去查看/var/log/secure日志文件,然后在findtime = 300 "5分钟" 之内符合条件
的记录下来，如果到达了maxretry = 3 "3次符合条件" 就阻挡这个IP连接22端口 bantime = 86400 "一天的时间".

2. POP3 保护拦截

cat /etc/fail2ban/filter.d/courierlogin.conf

failregex = LOGIN FAILED, .*, ip=\[<HOST>\]$

这里表示错误地输入用户名／密码的pop3连接.

开启 pop3 保护

vi /etc/fail2ban/jail.conf

[POP3]

enabled = true
filter = courierlogin
action = iptables[name=pop3, port=110, protocol=tcp]
logpath = /var/log/maillog
bantime = 1800
findtime = 300
maxretry = 15

大家应该懂得如何看了吧？我不写拉！好累。参数可以按照你实际要求修改噢～！

3. POP3-SSL 保护拦截

cat /etc/fail2ban/filter.d/courierlogin-ssl.conf

failregex = LOGIN FAILED, .*, ip=\[<HOST>\]$

这里表示错误地输入用户名／密码的pop3-ssl连接.

vi /etc/fail2ban/jail.conf

[POP3-SSL]

enabled = true
filter = courierlogin-ssl
action = iptables[name=pop3-ssl, port=995, protocol=tcp]
logpath = /var/log/maillog
bantime = 1800
findtime = 300
maxretry = 15

4 SMTP 保护拦截

cat /etc/fail2ban/filter.d/couriersmtp.conf

failregex = postfix/smtpd.* warning: unknown\[<HOST>\]: SASL LOGIN authentication failed: authentication failure

这里表示错误地输入用户名／密码的smtp连接.

vi /etc/fail2ban/jail.conf

[SMTP]

enabled = true
filter = couriersmtp
action = iptables[name=smtp, port=25:366, protocol=tcp]
logpath = /var/log/maillog
bantime = 1800
findtime = 300
maxretry = 15

参数可以按照你实际要求修改.

5. Extmail 登录保护

由于Extmail 的web mail 登入没有做到保护，现在加固吧！

vi /etc/fail2ban/filter.d/extmail.conf

failregex = extmail.*: user=.*, client=<HOST>, module=login, status=badlogin

这里表示错误地输入用户名／密码的web mail 登入.

vi /etc/fail2ban/jail.conf

[extmail]

enabled = true
filter = extmail
action = iptables[name=httpd, port=http, protocol=tcp]
logpath = /var/log/maillog
bantime = 300
findtime = 300
maxretry = 6

6. POSTFIX 保护User unknow 的试探.

不知道这个动作的意思先看看这篇文章。

http://hi.baidu.com/enjoyunix/blog/item/e8506058fd3c3189810a183a.html

vi /etc/fail2ban/filter.d/postfix.conf

failregex = reject: RCPT from (.*)\[<HOST>\]: 450

vi /etc/fail2ban/jail.conf

[POSTFIX]
enabled = true
filter = postfix
action = iptables[name=postfix, port=25, protocol=tcp]
logpath = /var/log/maillog
bantime = 43200
findtime = 1200
maxretry = 5

这里保护了User unknow 的试探以及垃圾邮件跳信攻击。

四看看iptables

iptables -L -nv

pkts bytes target     prot opt in     out     source               destination
    0     0 fail2ban-pop3-ssl tcp -- *      *       0.0.0.0/0            0.0.0.0/0           tcp dpt:995
773 83329 fail2ban-postfix tcp -- *      *       0.0.0.0/0            0.0.0.0/0           tcp dpt:25
299 12660 fail2ban-pop3 tcp -- *      *       0.0.0.0/0            0.0.0.0/0           tcp dpt:110
301 12740 fail2ban-ftp tcp -- *      *       0.0.0.0/0            0.0.0.0/0           tcp dpt:21
3354 253K fail2ban-SSH tcp -- *      *       0.0.0.0/0            0.0.0.0/0           tcp dpt:22
438 33979 fail2ban-httpd tcp -- *      *       0.0.0.0/0            0.0.0.0/0           tcp dpt:80

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain OUTPUT (policy ACCEPT 5703 packets, 829K bytes)
pkts bytes target prot opt in out source destination

Chain fail2ban-SSH (1 references)
pkts bytes target prot opt in out source destination
3354 253K RETURN all -- * * 0.0.0.0/0 0.0.0.0/0

Chain fail2ban-ftp (1 references)
pkts bytes target prot opt in out source destination
301 12740 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0

Chain fail2ban-httpd (1 references)
pkts bytes target prot opt in out source destination
438 33979 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0

Chain fail2ban-pop3 (1 references)
pkts bytes target prot opt in out source destination
299 12660 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0

Chain fail2ban-pop3-ssl (1 references)
pkts bytes target prot opt in out source destination
0 0 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0

Chain fail2ban-postfix (1 references)
pkts bytes target prot opt in out source destination
773 83329 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0

Chain fail2ban-smtp (0 references)
pkts bytes target prot opt in out source destination
0 0 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0

如何监察呢？

#watch -n 1 fail2ban-client status POSTFIX

看看那些垃圾邮件者真是好无聊！不断地试探我的邮件服务器呢。

五看看fail2ban的日志

# cat fail2ban.log | grep 'Ban '

2009-04-07 20:22:44,575 fail2ban.actions: WARNING [POSTFIX] Ban ip地址

就以看到过去有那些IP拦截了，以及是那个服务。

# cat fail2ban.log | grep '] Unban '

1. 修改/usr/bin/fail2ban-client文件的def __processCmd函数，在for c in cmd:那行下面增加一行：time.sleep(0.1)。保存、重启fail2ban。这里是修复一个fail2ban的bug。

2. 在/etc/fail2ban/jail.conf配置文件中，要确保每个action=那行的iptables[name=这里的name的字符长度不要超过21个。否则iptable chain name会超标

posted on 2013-05-02 16:48 Joe.genius 阅读(822) 评论(0) 编辑收藏举报