这撕想干嘛!!!!!!!!!!!!

[weixin_38050323]

Dec 21 08:02:25 www sshd(pam_unix)[29522]: authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=221.148.156.8
Dec 21 08:02:28 www sshd(pam_unix)[29529]: check pass; user unknown
Dec 21 08:02:28 www sshd(pam_unix)[29529]: authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=221.148.156.8
Dec 21 08:02:31 www sshd(pam_unix)[29536]: check pass; user unknown
Dec 21 08:02:31 www sshd(pam_unix)[29536]: authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=221.148.156.8
Dec 21 08:02:34 www sshd(pam_unix)[29544]: check pass; user unknown
Dec 21 08:02:34 www sshd(pam_unix)[29544]: authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=221.148.156.8

请问怎样防御