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How would a programme, such as uTorrent, have a good connection/be able to max out my download speeds even though I have not done any port forwarding? I was of the assumption that in order to get any semblance of download speed/quality you would need to forward ports?

Computer in question is behind a router...

Obviously, this was for totally legitimate purposes :)
 
Assuming router has it enabled and utorrent is using default settings then it will open ports automatically via UPnP (iirc, can't remember ever enabling it on mine for legit purposes too of course :))
 
UPnP is disabled on the router. Router is a TP-LINK (Archer C58).

uTorrent has the following parameters set wrt connection:
Enable UPnP port mapping
Enable NAT-PMP port mapping
Randomize port each start
Add Windows Firewall exception
 
NAT is stateful - so you requesting data from another peer involves an outbound connection from your PC, through a NAT device, and to the destination peer. The combination of source/destination port and IP address is remembered by whatever device is doing NAT, and inbound connections that match are allowed back through the NAT and passed along to your PC.

What won't work without explicitly opening ports (or allowing something to do it for you) are inbound connections, so it's likely that you won't have uploaded much.
 
Caged said:
What won't work without explicitly opening ports (or allowing something to do it for you) are inbound connections, so it's likely that you won't have uploaded much.
Click to expand...

This. You're good to go, as long as connectable peers are in the swarm.
 
Only if it needs to accept unsolicited inbound connections. I have UPnP disabled and it doesn't cause any issues.
 
Also technically, you don't need open ports to download at speed through utorrent, it's incoming connections that have issues (as in upload from your client).
 
Rainmaker said:
Quite. UPnP is one big fat hairy security hole and is broken. Case by case, device by device is the way to go.
Click to expand...
Yeah I have heard that as well and that used to be the first thing I'd do - disable UPnP on the router. On a related note, I sometimes find some games still offer me moderate NAT even though I've forwarded all the correct ports etc. This resolves itself and becomes open NAT when I enable UPnP so I am assuming there is some errant port the game is expecting but I have not explicitly forwarded it.
 
Most game developers do a really poor job of publishing the various network requirements of their games. Best way to know what you need to open is to run packet captures on your firewall.
 
Caged said:
Most game developers do a really poor job of publishing the various network requirements of their games. Best way to know what you need to open is to run packet captures on your firewall.
Click to expand...
Good shout.

The game in question is Rainbow Six: Siege (PC). According to various sources/forums (fora? forii?) there are some unpublished ports over the 50,000 range that the game uses. Apparently this randomises? I'll give "packet captures". Any specific app you'd recommend?
 
Caged said:
Most game developers do a really poor job of publishing the various network requirements of their games. Best way to know what you need to open is to run packet captures on your firewall.
Click to expand...
Yeah, also some routers (*glares at mine*) have a limitation on the number of port rules that can be active at any time. I doubt I'd have enough rules available for each game I might want to play.
 
If you just game off a single device then I'd be tempted to give it a static LAN IP and give that IP to your router as the DMZ address. The Windows firewall is more than capable.
 
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