防止暴力破解linux ssh等密码

可以使用denyhost这款开源软件，或者自己编写个检测脚本放入到crontab里面。实现自动检测那些某段时间内长时间试探密码的用户。

denyhost
下载地址 http://nchc.dl.sourceforge.net/project/denyhosts/denyhosts/2.6/DenyHosts-2.6.tar.gz

denyhost安装需要python支持，centos默认已安装。

tar -zxvf DenyHosts-2.6.tar.gz
cd DenyHosts-2.6
python setup.py install
cp /usr/share/denyhosts/denyhosts.cfg-dist /usr/share/denyhosts/denyhosts.cfg
vi /usr/share/denyhosts/denyhosts.cfg

# 用户登录的日志文件
SECURE_LOG = /var/log/auth.log

# 禁止登陆的主机文件
HOSTS_DENY = /etc/hosts.deny

# 清除已禁止主机的时间
PURGE_DENY = 5d

# 禁止的服务名
BLOCK_SERVICE = sshd

# 允许无效用户登录失败的次数
DENY_THRESHOLD_INVALID = 1

# 允许普通用户登陆失败的次数
DENY_THRESHOLD_VALID = 3

# 允许 root 用户登陆失败的次数
DENY_THRESHOLD_ROOT = 3

# 是否做域名反解
HOSTNAME_LOOKUP=NO

# 管理员邮件地址
ADMIN_EMAIL = [e-mail]

# SMTP 的相关设置
SMTP_HOST = mail.domain.com
SMTP_PORT = 25
SMTP_USERNAME=[e-mail]
SMTP_PASSWORD=password
SMTP_FROM = DenyHosts 
SMTP_SUBJECT = DenyHosts Report from domain.com

# DenyHosts 的日志文件
DAEMON_LOG = /var/log/denyhosts


设置启动脚本
cp /usr/share/denyhosts/daemon-control-dist /usr/share/denyhosts/daemon-control
chown root /usr/share/denyhosts/daemon-control
chmod 755 /usr/share/denyhosts/daemon-control
ln -s /usr/share/denyhosts/daemon-control /etc/init.d/denyhosts
chkconfig --level 345 denyhosts on
启动denyhosts
service denyhosts start

参考 http://www.kuaiwenba.com/article/324.html