In order to block a specific IP address, you need to add a Firewall filter rule.

Step-by-step guide

Follow these steps to add filter rule using Winbox:

  1. Go to IP>Firewall;
  2. Select tab "Filter rules";
  3. Click on the + to add new rule;
  4. Select tab "General";
  5. Choose Chain: Input;
  6. Select Src. Address - input your desired IP;
  7. Select tab "Action";
  8. Choose Action: Drop;
  9. Click OK, and the desired IP address will be blocked by a firewall filter. 


/ip firewall filter add chain=input src-address= action=drop

Chain "input" limit the connection to the device itself. To limit traffic going through the device use chain "forward". Please refer to the Building Your First Firewall