There is something on LFSFORUM regarding suspicious IP's on other peoples servers, it might be safer to remove the FTP address from the server info box on connection even though its fairly easy to get IP's of servers anyway :)
This is what they had found in their log file -
Jun 12 13:24:37 Accept : 185.204.1.185
Jun 12 13:24:37 Accept : 185.204.1.185
Jun 12 13:24:38 Received 281 : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Accept : 185.204.1.185
Jun 12 13:24:38 Received 281 : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Accept : 185.204.1.185
Jun 12 13:24:38 Received 281 : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Unknown protocol : 185.204.1.185
Jun 12 13:24:38 Accept : 185.204.1.185
Jun 12 13:24:39 Received 330 : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Accept : 185.204.1.185
Jun 12 13:24:39 Received 330 : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Accept : 185.204.1.185
Jun 12 13:24:39 Received 330 : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
Jun 12 13:24:39 Unknown protocol : 185.204.1.185
from what i have read their used to be a way where it kept trying to connect constantly and it would stop others being able to connect but that was supposed to have been fixed ages ago :)