If you are trying to access mikrotik router through winbox and you are confirm your admin password is wright and its not getting you login through winbox. You tried to login through Router console locally and you are able to login. but through winbox you are getting below error.
its giving Error : wrong username or password
So This is because your router has been compromised and the hacker has denied all logins from any IP address except his IP address . like below image.
Now you will have to remove there IP address to access through winbox.
1- Login in to your Mikrotik router console
2- go to under user /user >edit admin address and press Enter
VOS3000 188.8.131.52 does not support latest Kernel Versions. you have to downgrade Kernel
yum list kernel-2.6.32-358*
yum install kernel-2.6.32-358.el6.x86_64.rpm
DU command uses for disk uses you can use du command to check directory size.
for example you want to check directory size of a folder "database"
use -h for size in MB GB etc
# du -h ./database/