SSH如何防破解

你的linux服务器暴露在互联网之中，该服务器将会遭到互联网上的扫描软件进行骚描，并试图猜测SSH登录口令。

 

你会发现，每天会有多条SSH登录失败纪录。那些扫描工具将对你的服务器构成威胁，你必须设置复杂登录口令，并将尝试多次登录失败的IP给阻止掉，让其在一段时间内不能访问该服务器。

 

用DenyHosts可以阻止试图猜测SSH登录口令，它会分析/var/log/secure等日志文件，当发现同一IP在进行多次SSH密码尝试时就会记录IP到/etc/hosts.deny文件，从而达到自动屏蔽该IP的目的。

 

DenyHosts官方网站为：

 

DenyHosts安装

 

# tar -zxvf DenyHosts-2.6.tar.gz
# cd DenyHosts-2.6
# python setup.py install

DenyHosts参数配置

 

 

# cd /usr/share/denyhosts/             # DenyHosts默认安装目录
# cp denyhosts.cfg-dist denyhosts.cfg
# vi denyhosts.cfg                     # DenyHosts配置文件

SECURE_LOG = /var/log/secure                 #  ssh日志文件

 

#      format is: i[dhwmy]

#      Where i is an integer (eg. 7)

#            m = minutes

#            h = hours

#            d = days

#            w = weeks

#            y = years

#

# never purge:

PURGE_DENY = 50m                            #过多久后清除已阻止IP

 

HOSTS_DENY = /etc/hosts.deny                #将阻止IP写入到hosts.deny

                                                                                    

BLOCK_SERVICE = sshd                        #阻止服务名

                                                                                                      

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

                                                                                        

DENY_THRESHOLD_VALID = 10                   #允许普通用户登录失败的次数

                                                                                     

DENY_THRESHOLD_ROOT = 5                     #允许root登录失败的次数

 

WORK_DIR = /usr/local/share/denyhosts/data  #将deny的host或ip纪录到Work_dir中

 

DENY_THRESHOLD_RESTRICTED = 1               #设定 deny host 写入到该资料夹                 

 

LOCK_FILE = /var/lock/subsys/denyhosts      #将DenyHOts启动的pid纪录到LOCK_FILE中，

                                             已确保服务正确启动，防止同时启动多个服务。

                                                                    

HOSTNAME_LOOKUP=NO                          #是否做域名反解                                  

                                                                    

ADMIN_EMAIL = [e-mail]                 #设置管理员邮件地址  

                                                                 

DAEMON_LOG = /var/log/denyhosts             #自己的日志文件  

DAEMON_PURGE = 10m                          #该项与PURGE_DENY 设置成一样，也是清除

                                             hosts.deniedssh 用户的时间。

DenyHosts启动文件配置

# cp daemon-control-dist daemon-control
# chown root daemon-control
# chmod 700 daemon-control

# ./daemon-control     #DenyHosts命令格式

Usage: ./daemon-control {start [args...] | stop | restart [args...] | status | debug | condrestart [args...] }

 

For a list of valid args refer to:

$ denyhosts.py --help

 

# ./daemon-control start                   #启动DenyHosts

starting DenyHosts:    /usr/bin/env python /usr/bin/denyhosts.py --daemon --config=/usr/share/denyhosts/denyhosts.cfg

如果要使DenyHosts每次重起后自动启动还需做如下设置：

# ln -s /usr/share/denyhosts/daemon-control /etc/init.d/denyhosts
# chkconfig --add denyhosts
# chkconfig denyhosts on

# chkconfig –level 2345 denyhosts on


或者修改/etc/rc.local文件：

# vi /etc/rc.local
加入下面这条命令
/usr/share/denyhosts/daemon-control start