Linux利用hosts.deny防止暴力破解ssh

Myth丶恋晨 2023-05-31 14:00 22阅读 0赞

**Linux利用hosts.deny防止暴力破解ssh**

**1.背景**

**最近服务器被同一个ip多次访问我的22号端口，能用22号端口的无非是ssh连接。**

1.1 查看端口连接信息  
\[root@docker denyhosts\]\# ss -anp | grep tcp | grep sshd  
tcp LISTEN 0 128 \*:22 *:* users:((“sshd”,pid=3737,fd=3))  
tcp ESTAB 23 0 172.16.102.26:22 **147.16.11.17:56402** users:((“sshd”,pid=11463,fd=3))  
tcp ESTAB 0 36 172.16.102.26:22 116.24.66.59:25224 users:((“sshd”,pid=11263,fd=3))

1.2 查看系统安全日志  
\[root@docker denyhosts\]\# **tail -f /var/log/secure**  
Oct 17 19:33:48 izbp150ikdomqe3b32qaubz sshd\[11417\]: refused connect from 47.106.141.17 (147.16.11.17)  
Oct 17 19:34:12 izbp150ikdomqe3b32qaubz sshd\[11421\]: Failed password for root from 147.16.11.17 port 56398 ssh2  
Oct 17 19:34:13 izbp150ikdomqe3b32qaubz sshd\[11421\]: Failed password for root from 147.16.11.17 port 56398 ssh2  
Oct 17 19:34:13 izbp150ikdomqe3b32qaubz sshd\[11421\]: Connection closed by 147.16.11.17 \[preauth\]  
Oct 17 19:35:26 izbp150ikdomqe3b32qaubz sshd\[11428\]: pam\_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=147.16.11.17 user=root  
Oct 17 19:35:26 izbp150ikdomqe3b32qaubz sshd\[11428\]: pam\_succeed\_if(sshd:auth): requirement “uid >= 1000” not met by user “root”  
**Oct 17 19:35:28 izbp150ikdomqe3b32qaubz sshd\[11428\]: Failed password for root from 147.16.11.17 port 56400 ssh2**  
**Oct 17 19:36:23 izbp150ikdomqe3b32qaubz sshd\[11428\]: Failed password for root from 147.16.11.17 port 56400 ssh2**  
**Oct 17 19:36:24 izbp150ikdomqe3b32qaubz sshd\[11428\]: Failed password for root from 147.16.11.17 port 56400 ssh2**  
**Oct 17 19:36:24 izbp150ikdomqe3b32qaubz sshd\[11428\]: Connection closed by 147.16.11.17 \[preauth\]**

1.3 查询ip归属地

**2. 利用denyhosts 防止暴力破解ssh**

DenyHosts是[Python][]语言写的一个程序，它会分析sshd的日志文件（/var/log/secure），当发现重复的攻击时就会记录IP到/etc/hosts.deny文件，从而达到自动屏IP的功能。

思路：**利用读取到/var/log/secure登陆失败的IP信息，我们可以设定一个规则，如果登陆失败超过多少次，我们把这个IP写到 /etc/hosts.deny中，拒绝访问！**

**2.1** **先把始终允许的IP填入 /etc/hosts.allow ，因为自己访问超过了次数那就尴尬了。**

[root@docker denyhosts]# cat  /etc/hosts.allow 
    #
    # hosts.allow	This file contains access rules which are used to
    #		allow or deny connections to network services that
    #		either use the tcp_wrappers library or that have been
    #		started through a tcp_wrappers-enabled xinetd.
    #
    #		See 'man 5 hosts_options' and 'man 5 hosts_access'
    #		for information on rule syntax.
    #		See 'man tcpd' for information on tcp_wrappers
    #
    sshd: 147.16.11.17

**2.2** **安装DenyHosts 官方网站为：http://denyhosts.sourceforge.net**

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

**2.3 配置**

cd /usr/share/denyhosts/ 
    cp denyhosts.cfg-dist denyhosts.cfg 
    vi denyhosts.cfg
    
    SECURE_LOG = /var/log/secure  #要读取安全日志路径，默认的不管它
    HOSTS_DENY = /etc/hosts.deny #将阻止IP写入到hosts.deny，默认的不管它
    PURGE_DENY = 1d #设定过多久后清除已阻止IP （m=分钟，h=小时，d=天，w=周）
    BLOCK_SERVICE = sshd #阻止服务名
    DENY_THRESHOLD_INVALID = 5 #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 = 3 #允许root登录失败的次数**
    （上面3个登陆失败的次数建议不要设定太苛刻，以免自己输错了被列入黑名单了）
    DENY_THRESHOLD_RESTRICTED = 1 #设定 deny host 写入到该资料夹
    WORK_DIR = /usr/local/share/denyhosts/data #将deny的host或ip纪录到Work_dir中
    SUSPICIOUS_LOGIN_REPORT_ALLOWED_HOSTS=YES #假如设定为YES，那么已经设为白名单中的IP登陆失败也会被设为可疑，也会被列入黑名单中，设定NO的意思就相反。
    HOSTNAME_LOOKUP=YES #如果可以的话记录登陆失败的hostname
    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 = #设置管理员邮件地址 
    DAEMON_LOG = /var/log/denyhosts #自己的日志文件 
    DAEMON_PURGE = 1d #该项与PURGE_DENY 设置成一样，也是清除hosts.deniedssh 用户的时间。

**2.4 设置启动脚本**

cp daemon-control-dist daemon-control
    chown root daemon-control
    chmod 700 daemon-control
    完了之后执行daemon-contron start就可以了。
    **./daemon-control start**
    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
    ps -ef|grep denyhosts #检查是否启动
    
    [root@docker denyhosts]# ps -ef|grep denyhosts
    root     11309     1  0 19:29 ?        00:00:00 python /usr/bin/denyhosts.py --daemon --config=/usr/share/denyhosts/denyhosts.cfg
    root     11523 11265  0 19:51 pts/0    00:00:00 grep --color=auto denyhosts

vim /etc/hosts.deny \#查看内是否有禁止的IP，有的话说明已经成功了。

[root@docker denyhosts]# cat  /etc/hosts.deny 
    #
    # hosts.deny	This file contains access rules which are used to
    #		deny connections to network services that either use
    #		the tcp_wrappers library or that have been
    #		started through a tcp_wrappers-enabled xinetd.
    #
    #		The rules in this file can also be set up in
    #		/etc/hosts.allow with a 'deny' option instead.
    #
    #		See 'man 5 hosts_options' and 'man 5 hosts_access'
    #		for information on rule syntax.
    #		See 'man tcpd' for information on tcp_wrappers
    #
    # DenyHosts: Thu Oct 17 19:44:52 2019 | sshd: 147.16.11.17
    sshd: 147.16.11.17

[Python]: https://www.centos.bz/category/python/