用shell脚本来防SSH和vsftpd暴力破解,sshvsftpd脚本需求如下：此SH

用shell脚本来防SSH和vsftpd暴力破解,sshvsftpd脚本需求如下：此SH

新近刚上的FTP备份服务器，例行检查/var/log/secure日志时，发现不少sshd和vsftpd失败认证信息，很明显有人想用暴力破解工具窃取密码，所以需要编写一个安全脚本防止。

脚本需求如下：此SHELL脚本放在crontab计划任务里，每隔6小时（此时间根据实际情况来定义）就去读取/var/log/secure脚本，取出里面恶意猜测IP，如果单位时间内（一星期）的连接数是高于一个阀值，例如100（此阀值也可以根据实际情况来定义），则将其加进/etc/hosts.deny黑名单里，如果低于此阀值，则无视此IP。

/var/log/secure里认证失败信息如下：

Nov 28 10:18:08 centos2 sshd[7556]: Connection closed by 222.216.30.109

Nov 28 10:18:08 centos2 sshd[7557]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=222.216.30.109user=root

Nov 28 10:18:09 centos2 sshd[7559]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=222.216.30.109user=root

Nov 28 10:18:10 centos2 sshd[7551]: Failed password for root from 222.216.30.109 port 2391 ssh2

Nov 28 10:18:10 centos2 sshd[7552]: Connection closed by 222.216.30.109

Nov 28 10:18:10 centos2 sshd[7553]: Failed password for root from 222.216.30.109 port 2397 ssh2

Nov 28 10:18:10 centos2 sshd[7554]: Connection closed by 222.216.30.109

Nov 28 10:18:11 centos2 sshd[7557]: Failed password for root from 222.216.30.109 port 2401 ssh2

Nov 28 10:18:11 centos2 sshd[7558]: Connection closed by 222.216.30.109

Nov 28 10:18:11 centos2 sshd[7559]: Failed password for root from 222.216.30.109 port 2403 ssh2

Nov 28 10:18:11 centos2 sshd[7560]: Connection closed by 222.216.30.109

Nov 28 10:37:01 centos2 vsftpd: pam_unix(vsftpd:auth): check pass; user unknown

Nov 28 10:37:01 centos2 vsftpd: pam_unix(vsftpd:auth): authentication failure; logname= uid=0 euid=0 tty=ftp ruser=hello rhost=centos1.cn7788.com

Nov 28 10:37:01 centos2 vsftpd: pam_succeed_if(vsftpd:auth): error retrieving information about user hello

Nov 28 10:37:19 centos2 vsftpd: pam_unix(vsftpd:auth): check pass; user unknown

Nov 28 10:37:19 centos2 vsftpd: pam_unix(vsftpd:auth): authentication failure; logname= uid=0 euid=0 tty=ftp ruser=yhc rhost=centos1.cn7788.com

Nov 28 10:37:19 centos2 vsftpd: pam_succeed_if(vsftpd:auth): error retrieving information about user yhc

Nov 28 10:37:36 centos2 vsftpd: pam_unix(vsftpd:auth): check pass; user unknown

Nov 28 10:37:36 centos2 vsftpd: pam_unix(vsftpd:auth): authentication failure; logname= uid=0 euid=0 tty=ftp ruser=yuhongchun rhost=centos1.cn7788.com

Nov 28 10:37:36 centos2 vsftpd: pam_succeed_if(vsftpd:auth): error retrieving information about user yuhongchun

Nov 28 10:42:44 centos2 vsftpd: pam_unix(vsftpd:auth): check pass; user unknown

Nov 28 10:42:44 centos2 vsftpd: pam_unix(vsftpd:auth): authentication failure; logname= uid=0 euid=0 tty=ftp ruser=yuhongchun rhost=114.112.169.70

Nov 28 10:42:44 centos2 vsftpd: pam_succeed_if(vsftpd:auth): error retrieving information about user yuhongchun

Nov 28 10:42:56 centos2 vsftpd: pam_unix(vsftpd:auth): check pass; user unknown

Nov 28 10:42:56 centos2 vsftpd: pam_unix(vsftpd:auth): authentication failure; logname= uid=0 euid=0 tty=ftp ruser=andrewyu rhost=114.112.169.70

Nov 28 10:42:56 centos2 vsftpd: pam_succeed_if(vsftpd:auth): error retrieving information about user andrewyu

我们观察下/var/log/secure文件轮询特征，如下所示：

[root@centos2 log]# ls -lsart secure.*

512 -rw------- 1 root root 516379 11-04 01:31 secure.4

660 -rw------- 1 root root 668192 11-11 00:05 secure.3

304 -rw------- 1 root root 306589 11-17 10:33 secure.2

484 -rw------- 1 root root 488620 11-25 02:33 secure.1

基本上，/var/log/secure文件是以星期为轮询周期的，如果对安全要求严格的朋友还可以本着“一个不放过”的原则来抓取上面的旧secure的恶意IP，然后扔进/etc/hosts.deny文件里。下面我们就们就要想办法高效的来抓取这些恶意IP，如果参考原始版本的SHELL脚本写法，，我们这里要抓取secure日志中的侦测vsftpd及sshd服务的IP地址，我们可以用如下命令，命令如下所示：

cat /var/log/secure | awk '/Failed/{print $(NF-3)}'| sort| uniq -c| awk '{print $2"="$1;}'

很明显，这样是取不到vsftpd失败的IP值的，sshd日志失败信息跟vsftpd日志失败信息不一样，我写了几种awk混合sed的方法，测试了效率，感觉用awk脚本速度是最快的，大家也可以写几种，用time命令测试下；最后精简了下代码，完成了整个脚本，脚本内容如下所示：

#!/bin/bash

awk '{for(i=1;i<=NF;i++){if($i ~ /rhost/)print substr($i,7)}}' /var/log/secure | sort | uniq-c>/root/black.txt

DEFINE="100"

cat /root/black.txt |while read LINE

do

NUM=`echo $LINE |awk '{print $1}'`

host=`echo $LINE|awk '{print $2}'`

if [ $NUM -gt $DEFINE ];

then

grep $host/etc/hosts.deny > /dev/null

if [ $? -gt 0 ];

then

echo "sshd:$host" >> /etc/hosts.deny

echo "vsftpd:$host" >> /etc/hosts.deny

fi

fi

done

脚本运行一段时间后，我们可以观察此脚本涉及到的一些文件，如/root/black.txt，结果如下所示：

[root@centos2 ~]# cat /root/black.txt

2 113.17.144.156

4 114.112.51.208

4 114.112.69.170

169 118-163-227-50.hinet-ip.hinet.net

8 119.188.7.200

8 122.70.130.11

61 124.248.32.246

12 183.203.14.121

3 189.26.255.11

56 199.204.237.60

3 199.30.53.220

5 201.236.80.4

6 220.172.191.31

30 222.216.30.109

60 222.253.159.111

58 223.4.180.23

166 58.221.42.178

1 61.132.4.85

152 61.142.106.34

22 61.167.33.222

7 85.126.166.83

166 www.b-nets.com

/etc/hosts.deny脚本内容如下：

sshd:124.248.32.246

vsftpd:124.248.32.246

sshd:199.204.237.60

vsftpd:199.204.237.60

sshd:222.253.159.111

vsftpd:222.253.159.111

sshd:223.4.180.23

vsftpd:223.4.180.23

sshd:58.221.42.178

vsftpd:58.221.42.178

sshd:61.142.106.34

vsftpd:61.142.106.34

sshd:118-163-227-50.hinet-ip.hinet.net

vsftpd:118-163-227-50.hinet-ip.hinet.net

sshd:www.b-nets.com

vsftpd:www.b-nets.com

最后，我们将此shell脚本放进crontab里，每间隔六小时就运行一次，命令如下：

* */6 * * * root /bin/bash /root/hostsdeny.sh >> /dev/null 2>&1

由于/var/log/secure日志是以星期为轮询的，此脚本执行频率可自行设定，如果感觉服务器被频繁侦测，执行频率间隔可设置短些，反之，可设置长些。