SSH如何防破解

 当你的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：http://denyhosts.sourcefor...

DenyHosts安装

[root@switch DenyHost]# ls -l

总用量 44

-rw-------  1 root root 42667  8月  5 19:23 DenyHosts-2.6.tar.gz

[root@switch DenyHost]# tar -zxvf DenyHosts-2.6.tar.gz

DenyHosts-2.6/

DenyHosts-2.6/PKG-INFO

DenyHosts-2.6/denyhosts.py

DenyHosts-2.6/denyhosts.cfg-dist

DenyHosts-2.6/setup.py

DenyHosts-2.6/DenyHosts/

DenyHosts-2.6/DenyHosts/prefs.py

DenyHosts-2.6/DenyHosts/report.py

DenyHosts-2.6/DenyHosts/lockfile.py

DenyHosts-2.6/DenyHosts/__init__.py

DenyHosts-2.6/DenyHosts/plugin.py

DenyHosts-2.6/DenyHosts/denyfileutil.py

DenyHosts-2.6/DenyHosts/deny_hosts.py

DenyHosts-2.6/DenyHosts/regex.py

DenyHosts-2.6/DenyHosts/sync.py

DenyHosts-2.6/DenyHosts/counter.py

DenyHosts-2.6/DenyHosts/old-daemon.py

DenyHosts-2.6/DenyHosts/util.py

DenyHosts-2.6/DenyHosts/daemon.py

DenyHosts-2.6/DenyHosts/python_version.py

DenyHosts-2.6/DenyHosts/allowedhosts.py

DenyHosts-2.6/DenyHosts/filetracker.py

DenyHosts-2.6/DenyHosts/loginattempt.py

DenyHosts-2.6/DenyHosts/restricted.py

DenyHosts-2.6/DenyHosts/purgecounter.py

DenyHosts-2.6/DenyHosts/version.py

DenyHosts-2.6/DenyHosts/constants.py

DenyHosts-2.6/CHANGELOG.txt

DenyHosts-2.6/LICENSE.txt

DenyHosts-2.6/daemon-control-dist

DenyHosts-2.6/plugins/

DenyHosts-2.6/plugins/README.contrib

DenyHosts-2.6/plugins/shorewall_allow.sh

DenyHosts-2.6/plugins/shorewall_deny.sh

DenyHosts-2.6/plugins/test_deny.py

DenyHosts-2.6/scripts/

DenyHosts-2.6/scripts/restricted_from_invalid.py

DenyHosts-2.6/scripts/restricted_from_passwd.py

DenyHosts-2.6/README.txt

DenyHosts-2.6/MANIFEST.in

 

[root@switch DenyHost]# cd DenyHosts-2.6

[root@switch DenyHosts-2.6]# ls

CHANGELOG.txt        DenyHosts           denyhosts.py  MANIFEST.in  plugins     scripts

daemon-control-dist  denyhosts.cfg-dist  LICENSE.txt   PKG-INFO     README.txt  setup.py

 

[root@switch DenyHosts-2.6]# python setup.py install

running install

running build

running build_py

creating build

creating build/lib

creating build/lib/DenyHosts

copying DenyHosts/deny_hosts.py -> build/lib/DenyHosts

copying DenyHosts/denyfileutil.py -> build/lib/DenyHosts

copying DenyHosts/version.py -> build/lib/DenyHosts

copying DenyHosts/__init__.py -> build/lib/DenyHosts

copying DenyHosts/util.py -> build/lib/DenyHosts

copying DenyHosts/constants.py -> build/lib/DenyHosts

copying DenyHosts/restricted.py -> build/lib/DenyHosts

copying DenyHosts/plugin.py -> build/lib/DenyHosts

copying DenyHosts/sync.py -> build/lib/DenyHosts

copying DenyHosts/prefs.py -> build/lib/DenyHosts

copying DenyHosts/report.py -> build/lib/DenyHosts

copying DenyHosts/filetracker.py -> build/lib/DenyHosts

copying DenyHosts/python_version.py -> build/lib/DenyHosts

copying DenyHosts/loginattempt.py -> build/lib/DenyHosts

copying DenyHosts/allowedhosts.py -> build/lib/DenyHosts

copying DenyHosts/regex.py -> build/lib/DenyHosts

copying DenyHosts/purgecounter.py -> build/lib/DenyHosts

copying DenyHosts/old-daemon.py -> build/lib/DenyHosts

copying DenyHosts/daemon.py -> build/lib/DenyHosts

copying DenyHosts/counter.py -> build/lib/DenyHosts

copying DenyHosts/lockfile.py -> build/lib/DenyHosts

running build_scripts

creating build/scripts-2.3

copying and adjusting denyhosts.py -> build/scripts-2.3

changing mode of build/scripts-2.3/denyhosts.py from 644 to 755

running install_lib

creating /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/deny_hosts.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/denyfileutil.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/version.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/__init__.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/util.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/constants.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/restricted.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/plugin.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/sync.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/prefs.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/report.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/filetracker.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/python_version.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/loginattempt.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/allowedhosts.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/regex.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/purgecounter.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/old-daemon.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/daemon.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/counter.py -> /usr/lib/python2.3/site-packages/DenyHosts

copying build/lib/DenyHosts/lockfile.py -> /usr/lib/python2.3/site-packages/DenyHosts

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/deny_hosts.py to deny_hosts.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/denyfileutil.py to denyfileutil.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/version.py to version.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/__init__.py to __init__.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/util.py to util.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/constants.py to constants.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/restricted.py to restricted.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/plugin.py to plugin.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/sync.py to sync.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/prefs.py to prefs.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/report.py to report.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/filetracker.py to filetracker.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/python_version.py to python_version.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/loginattempt.py to loginattempt.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/allowedhosts.py to allowedhosts.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/regex.py to regex.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/purgecounter.py to purgecounter.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/old-daemon.py to old-daemon.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/daemon.py to daemon.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/counter.py to counter.pyc

byte-compiling /usr/lib/python2.3/site-packages/DenyHosts/lockfile.py to lockfile.pyc

running install_scripts

copying build/scripts-2.3/denyhosts.py -> /usr/bin

changing mode of /usr/bin/denyhosts.py to 755

running install_data

creating /usr/share/denyhosts

copying denyhosts.cfg-dist -> /usr/share/denyhosts

copying setup.py -> /usr/share/denyhosts

copying daemon-control-dist -> /usr/share/denyhosts

copying CHANGELOG.txt -> /usr/share/denyhosts

copying README.txt -> /usr/share/denyhosts

creating /usr/share/denyhosts/scripts

copying scripts/restricted_from_invalid.py -> /usr/share/denyhosts/scripts

copying scripts/restricted_from_passwd.py -> /usr/share/denyhosts/scripts

creating /usr/share/denyhosts/plugins

copying plugins/test_deny.py -> /usr/share/denyhosts/plugins

copying plugins/README.contrib -> /usr/share/denyhosts/plugins

copying plugins/shorewall_deny.sh -> /usr/share/denyhosts/plugins

copying plugins/shorewall_allow.sh -> /usr/share/denyhosts/plugins

copying LICENSE.txt -> /usr/share/denyhosts

 

DenyHosts参数配置

[root@switch DenyHosts-2.6]# cd /usr/share/denyhosts/  #DenyHosts默认安装目录

[root@switch denyhosts]# cp denyhosts.cfg-dist denyhosts.cfg

[root@switch denyhosts]# 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 = [email protected]         #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

[root@switch denyhosts]# cp daemon-control-dist daemon-control

[root@switch denyhosts]# chown root daemon-control

[root@switch denyhosts]# chmod 700 daemon-control

[root@switch denyhosts]# ./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

[root@switch denyhosts]# ./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：

[root@switch denyhosts]# ln -s /usr/share/denyhosts/daemon-control /etc/init.d/denyhosts

[root@switch denyhosts]# chkconfig --add denyhosts

[root@switch denyhosts]# chkconfig  denyhosts on

[root@switch denyhosts]#chkconfig –level 2345 denyhosts on

或者修改/etc/rc.local文件：

root@switch denyhosts]# vi /etc/rc.local

加入下面这条命令

/usr/share/denyhosts/daemon-control start

 

[root@switch denyhosts]# tail -f /var/log/secure

Aug  5 19:20:51 switch sshd[5831]: Accepted password for root from ::ffff:192.168.1.31 port 1744 ssh2

Aug  5 19:21:00 switch sshd[5831]: Received disconnect from ::ffff:192.168.1.31: 0:

Aug  5 19:21:02 switch sshd[5865]: Accepted password for root from ::ffff:192.168.1.31 port 1745 ssh2

Aug  5 19:30:25 switch sshd[5865]: Received disconnect from ::ffff:192.168.1.31: 0:

Aug  5 19:33:48 switch sshd[5962]: Failed password for test from ::ffff:192.168.1.31 port 175

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