Yes, it is entirely possible to apply a firewall rule to a specific client on a MikroTik device using RouterOS.

You can configure firewall rules to target a specific client based on their IP address, MAC address, or any other identifiable criteria. We explain how to do it step by step:

Step 1: Identify the Client

First, you need to identify the specific client to whom you want to apply the firewall rule. This is usually done using the client's IP address or MAC address.

Step 2: Access MikroTik RouterOS

Use WinBox, WebFig, or SSH to access your MikroTik device settings.

Step 3: Firewall Rule Configuration

1. Navigate to Firewall Settings:
   • In WinBox: Go to IP > Firewall.
   • In WebFig: Access IP > Firewall from the menu.
2. Add a New Rule in the Firewall Chain:
   • Go to the tab Filter Rules and click + to add a new rule.
3. Configure Rule Details:
   • General: Select the string (input, forward, output) depending on whether the traffic is incoming, outgoing or internal.
   • Advanced: Here you can specify additional parameters such as protocol types, ports, etc.
   • Mr. Address or Src. Mac Address: Enter the IP or MAC address of the specific client you want to apply the rule to.
   • Action: Choose what will happen when the rule conditions are met (for example, drop, reject, accept).
4. Comments: Add a comment to your rule to remind you of its purpose (optional).
5. Save: Click OK o Apply To save the settings.

Step 4: Verification

Verify that the rule is working correctly:

• Monitor the Log in MikroTik to see if the actions defined in your rule are being executed as expected.
• You can use tools like Torch in MikroTik to view real-time traffic and confirm that the rule is filtering properly.

Additional considerations

• Security: Make sure the rules don't expose the device or network to additional security risks.
• Testing: Perform extensive testing to ensure that the rules do not affect legitimate traffic from other clients or services.

Configuring client-specific firewall rules on MikroTik devices allows great flexibility and control over network security, allowing you to manage access and protect the network from unwanted or potentially dangerous traffic.