Bruteforce: в чем проблема?

2018-04-01T22:39:14.831836+02:00 vz4vps101 sshd[18362]: Invalid user nagios from 188.225.75.189 
2018-04-01T22:39:14.952337+02:00 vz4vps101 sshd[18362]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=188.225.75.189 
2018-04-01T22:39:17.047315+02:00 vz4vps101 sshd[18362]: Failed password for invalid user nagios from 188.225.75.189 port 54878 ssh2 
2018-04-01T22:39:17.099989+02:00 vz4vps101 sshd[18363]: Received disconnect from 188.225.75.189: 11: Normal Shutdown, Thank you for playing 
2018-04-04T20:57:19.158858+02:00 vz4vps101 sshd[21860]: Invalid user dummy from 188.225.75.189 
2018-04-04T20:57:19.268252+02:00 vz4vps101 sshd[21860]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=188.225.75.189 
2018-04-04T20:57:21.191597+02:00 vz4vps101 sshd[21860]: Failed password for invalid user dummy from 188.225.75.189 port 55157 ssh2 
2018-04-04T20:57:21.248399+02:00 vz4vps101 sshd[21861]: Received disconnect from 188.225.75.189: 11: Normal Shutdown, Thank you for playing 
2018-04-04T20:58:29.711106+02:00 vz4vps101 sshd[22047]: Invalid user dummy from 188.225.75.189 
2018-04-04T20:58:29.818612+02:00 vz4vps101 sshd[22047]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=188.225.75.189 
2018-04-04T20:58:31.351845+02:00 vz4vps101 sshd[22047]: Failed password for invalid user dummy from 188.225.75.189 port 44908 ssh2

Можете помочь понять в чем проблема?