In a MikroTik router, what does the 'chain' parameter indicate in a firewall rule?

The 'chain' parameter in a MikroTik router's firewall rule determines the specific point in the packet-processing flow where the rule will be applied. Chains are categorized as input, output, or forward, which correspond to the direction of network traffic.

For instance, the input chain processes traffic that is destined for the router itself, while the output chain deals with traffic originating from the router. The forward chain is used for packets traversing through the router without being destined for it. By specifying the chain, the administrator defines when and how the firewall rule interacts with the traffic relative to its direction. This precision is crucial for effective traffic management and security policy enforcement within the network.