root下在/etc/pam.d/sshd文件的#%PAM-1.0下加一行：
#%PAM-1.0
auth required pam_tally2.so deny=3 unlock_time=180
auth required pam_sepermit.so
auth include password-auth
account required pam_nologin.so
account include password-auth
password include password-auth
# pam_selinux.so close should be the first session rule
session required pam_selinux.so close
session required pam_loginuid.so
# pam_selinux.so open should only be followed by sessions to be executed in the user context
session required pam_selinux.so open env_params
session required pam_namespace.so
session optional pam_keyinit.so force revoke
session include password-auth
解釋：
deny 設置普通用戶和root用戶連續錯誤登陸的最大次數，超過最大次數，則鎖定該用戶；
unlock_time 設定普通用戶鎖定后，多少時間后解鎖，單位是秒；
參考：
1、（https://blog.csdn.net/weixin_34117522/article/details/91664010）
2、（https://blog.csdn.net/weixin_43822878/article/details/93018223）
3、（https://wenku.baidu.com/view/411ba45a4b73f242336c5fdd.html）