Example npf config to redirect ports 80/443 to unprivileged ports

npf.conf

$ext_if = "vioif0"
$ext_v4 = inet4(vioif0)

map $ext_if dynamic XXX.XXX.XXX.XXX port 8080 <- $ext_v4 port 80
map $ext_if dynamic XXX.XXX.XXX.XXX port 4443 <- $ext_v4 port 443

group default {
        pass final on lo0 all
        pass final on $ext_if all
}