I have opened a number of ports, and am familiar enough with
pfctl, but even though I have opened various ports, then show up as "filtered" - which means of course that they are not open.
How can I open them, or is it a function of having a suitable app using them? For example
pass in proto tcp from any to any port 53
In a scan this shows up as
53 dns Filtered
How can I open this port?