This is more of a general question about how the Draytek firewall works. I'm trying to understand the relationship between Open Ports and the firewall filters.

If I open up a port, say 25 under Nat->open ports to a particular computer, do I also have to make a corresponding rule on the firewall? Or does the open port bypass the firewall altogether.

I'm assuming with port redirection that I would still have to have an active firewall filter rule to access the destination port.

If you have a firewall filter rule set up that would block port 25 or all traffic then it would be necessary, but if there's not a specific rule set up to block port 25, you would only only need to forward the port since the router wouldn't block inbound traffic from a forwarded port unless told to.

so by default it blocks everything, but if you open the port that won't be blocked unless there was an express rule?