When you use hfs directly in contact with the internet you can use the ban because hfs can identify the distant user by his IP, but by way of stunnel, this one passes on in hfs only the address ip 127.0.0.1, that's right which rejetto wants to say

However by using a particular option of stunnel, it is possible to define the address of the network connection of the card to mark the difference
[https]
;accept = [address:]port of stunnel
accept = 0.0.0.0:443
;connect = [address:]port of HFS
connect = 127.0.0.1:80
;local =Ip of your computer on the network viewed by the hfs server
local = 192.168.1.xxx
TIMEOUTclose = 0