Yes, it is possible to configure a gateway on a MikroTik device that uses a dynamic public IP address. This setting is useful when the MikroTik device is connected to an ISP that assigns IP addresses dynamically, as is common with residential or small business connections.

We explain how you can configure a gateway with a dynamic IP in MikroTik using DHCP to obtain the IP address and then configure this address as your default gateway.

Steps to Configure a Gateway with Dynamic IP in MikroTik

1. DHCP Client Configuration:
   • Make sure your WAN interface (the interface connected to the ISP) is configured to obtain an IP address using DHCP. This can be done from WinBox or via the CLI.
   By CLI:
   
   /ip dhcp-client add interface=ether1 disabled=no
2. 
   By WinBox:
   • Go to IP -> DHCP Client, select the corresponding interface (for example, ether1), and make sure it is enabled.
3. Set the Default Gateway:
   • Generally, when you configure a DHCP client in MikroTik, it automatically configures the default route if the DHCP server provides this information. However, you can check or modify this manually if necessary.
   By CLI:
   
   /ip route add gateway=<nombre-de-tu-interfaz-dhcp>
   
   By WinBox:
   • Go to IP -> Routes and make sure there is a route with dst-address=0.0.0.0/0 y gateway configured to your DHCP interface.
4. Verification and Monitoring:
   • Verify that your MikroTik is correctly receiving the dynamic public IP and that it can use it as a gateway.
   Useful commands to verify:
   
   /ip dhcp-client print
/ip address print
/ip route print
   
   • These commands will help you verify that the IP address is correctly assigned to the interface, and that a default route exists that uses this IP address.

Additional considerations

• Security: Make sure your firewall is properly configured to protect your network, especially when you are using a dynamic public IP.
• DDNS (Dynamic DNS): If you need to access your network from outside on a consistent basis, consider setting up a DDNS service. This will allow you to access your MikroTik device even when the public IP address changes.

Configuring a gateway with a dynamic public IP in MikroTik is a relatively simple process and allows you to make the most of Internet connections with dynamic IPs, maintaining a flexible and adaptable network configuration.