[FTP] vsftpd(pam_unix) check pass; user unknown 是什么意思呢？

[weixin_38051598]

Sep 12 20:30:53 www vsftpd(pam_unix)[24610]: check pass; user unknown表示什么意思呢？
以下日志表示我受到了攻击吗？有被攻击成功吗？

Sep 12 17:28:49 www vsftpd: warning: can't get client address: Bad file descriptor
Sep 12 17:37:32 www vsftpd: warning: can't get client address: Bad file descriptor
Sep 12 20:30:53 www vsftpd: warning: can't get client address: Bad file descriptor
Sep 12 20:30:53 www vsftpd(pam_unix)[24610]: check pass; user unknown
Sep 12 20:30:53 www vsftpd(pam_unix)[24610]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=218.72.201.36
Sep 12 20:31:02 www sshd(pam_unix)[24612]: authentication failure; logname= uid=0 euid=0 tty=NODEVssh ruser= rhost=202.57.139.183.sta.isp-thailand.com  user=root
Sep 12 20:31:07 www sshd(pam_unix)[24614]: authentication failure; logname= uid=0 euid=0 tty=NODEVssh ruser= rhost=202.57.139.183.sta.isp-thailand.com  user=root
Sep 12 20:31:15 www sshd(pam_unix)[24616]: authentication failure; logname= uid=0 euid=0 tty=NODEVssh ruser= rhost=202.57.139.183.sta.isp-thailand.com  user=root
Sep 12 20:31:19 www sshd(pam_unix)[24618]: authentication failure; logname= uid=0 euid=0 tty=NODEVssh ruser= rhost=202.57.139.183.sta.isp-thailand.com  user=root
Sep 12 20:31:24 www sshd(pam_unix)[24620]: authentication failure; logname= uid=0 euid=0 tty=NODEVssh ruser= rhost=202.57.139.183.sta.isp-thailand.com  user=root
Sep 12 20:31:34 www sshd(pam_unix)[24622]: authentication failure; logname= uid=0 euid=0 tty=NODEVssh ruser= rhost=202.57.139.183.sta.isp-thailand.com  user=root
Sep 12 20:55:25 www vsftpd: warning: can't get client address: Bad file descriptor
Sep 12 20:56:38 www vsftpd: warning: can't get client address: Bad file descriptor
Sep 12 20:56:38 www vsftpd(pam_unix)[24650]: check pass; user unknown
Sep 12 20:56:38 www vsftpd(pam_unix)[24650]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=61.177.24.42
Sep 12 21:19:30 www vsftpd: warning: can't get client address: Bad file descriptor
Sep 12 21:19:30 www vsftpd(pam_unix)[24670]: check pass; user unknown
Sep 12 21:19:30 www vsftpd(pam_unix)[24670]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=61.177.24.42