Forward port opens port to all PCs?

[MrGlasspoole]

Hi,

i open a port for uTorrent.
With commercial routers it was always the case that the port was just
open on the PC it was forwarded. But now if i make a port check the
port is also open on another PC.

What i also don't understand is that uTorrent is not in the Windows firewall
on the other PC but appears open?

I made the check with: https://www.grc.com/x/ne.dll?bh0bkyd2

[johnpoz]

What do you mean open to all pcs.. You are forwarding to 1 IP 192.168.0.6

Does not matter what pc you run the grc check from.. It hits your public IP, that is fowarded to this 0.6 IP – so yeah it should show open.

[MrGlasspoole]

Ok. So it's normal that the ports are then open on all PCs?

Whit commercial routers it was always the case that port forwarding
did only work to one PC. Means if you had the same application on two
PCs you had to use different ports.

So if i have a HTTP Server port 80 is open everywhere?

[johnpoz]

Again its NOT open on all PC..

How are you thinking it is???  When you check from grc its only talking to your 1 PUBLIC IP!!!  Which that port then gets forwarded to 1 PC behind the nat.. How do you think its open on all pcs??

It is not possible to forward the same port to multiple IPs behind a nat.

[doktornotor]

Layer 8 issue.

[MrGlasspoole]

Ok, i thought this port checkers check only on the PC you run them.

[KOM]

It's going to check your public presence only.  It can't easily tell if you're behind some NAT devices.  So even though you're running a port scan from your PC behind the firewall, the scan is really targeting the firewall and not your PC.