I found a way to forward ports 80 and 443 to other arbitrary ports (3000 and 3001 in my case) using ipfw. But ipfw is deprecated and replaced by pfctl. Here are my ipfw declarations:
sudo ipfw flush
sudo ipfw add 100 fwd 127.0.0.1,3000 tcp from any to me 443
sudo ipfw add 200 fwd 127.0.0.1,3001 tcp from any to me 80
sudo ipfw show
How can I do the same thing with pfctl please?