How many default firewall chains exist in MikroTik RouterOS?

In MikroTik RouterOS, there are three default firewall chains that play a crucial role in the functioning of the firewall. These chains are as follows:

1. Input Chain: This chain handles packets destined for the router itself. It is used to control access to the router's services and ensure that only authorized traffic can reach the router.

2. Forward Chain: The forward chain is responsible for packets that are passing through the router, meaning those that are not destined for the router itself. This chain is used to manage traffic that is routing between interfaces without being processed by the router.

3. Output Chain: This chain deals with packets originating from the router itself, meaning traffic that the router is sending out. It is used to define rules for outgoing traffic in order to control what can leave the router.

These three chains work together to provide a comprehensive firewall solution within MikroTik's configuration, allowing users to create specific rules for managing and securing network traffic effectively. The existence of these three chains ensures a layered approach to security and traffic management, making it essential for users to understand and utilize them appropriately in their routing and security configurations.