Logwatch error or possible crack attempt?

[Lorn Miller]

Logwatch for Sep 22
 --------------------- pam_unix Begin ------------------------ 

<cut>

vsftpd:
   Unknown Entries:
      authentication failure; logname= uid=0 euid=0 tty= ruser=
rhost=80.141.233.183 : 16 Time(s)
      check pass; user unknown: 16 Time(s)


 ---------------------- pam_unix End ------------------------- 


Is there a local process that would do that or did someone try to get
into my ftp server 16 times?  Where could I check to see if they
succeeded?