sudo apt-get install fail2ban

2、修改配置

vi /etc/fail2ban/jail.conf

修改如下

[ssh]
enabled = true
prot = 22
filter = sshd
logpath = /var/log/auth.log      
bantime = -1
maxretry = 5

3、重启ssh

sudo service ssh restart

4、查看被封禁状态

fail2ban-client status sshd  

原文链接

注：不小心测试被封禁使用云机器直接登录执行：

fail2ban-client set sshd unbanip 111.111.111.111