系统日志信息。不知道咋回事。。求解。。。。。。。

Nov 30 17:19:36 localhost dovecot(pam_unix)[975]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:36 localhost dovecot(pam_unix)[981]: check pass; user unknown
Nov 30 17:19:36 localhost dovecot(pam_unix)[981]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:36 localhost dovecot(pam_unix)[982]: check pass; user unknown
Nov 30 17:19:36 localhost dovecot(pam_unix)[982]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:37 localhost dovecot(pam_unix)[983]: check pass; user unknown
Nov 30 17:19:37 localhost dovecot(pam_unix)[983]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:37 localhost dovecot(pam_unix)[984]: check pass; user unknown
Nov 30 17:19:37 localhost dovecot(pam_unix)[984]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:37 localhost dovecot(pam_unix)[985]: check pass; user unknown
Nov 30 17:19:37 localhost dovecot(pam_unix)[985]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:37 localhost dovecot(pam_unix)[986]: check pass; user unknown
Nov 30 17:19:37 localhost dovecot(pam_unix)[986]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:37 localhost dovecot(pam_unix)[992]: check pass; user unknown
Nov 30 17:19:37 localhost dovecot(pam_unix)[992]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:19:37 localhost dovecot(pam_unix)[993]: check pass; user unknown
Nov 30 17:19:37 localhost dovecot(pam_unix)[993]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Nov 30 17:21:53 localhost sshd(pam_unix)[26296]: session closed for user swq