I be sailin’ the digital seas with a trusty QNAP OS and the mighty QBittorrent, but I be a greenhorn in this life on the high seas. Me heart’s desire be to contribute to our pirate brotherhood by becoming a proper seederman.

Be ye privy to a treasure map, a definitive guide, that can steer me in the right direction to turn me NAS into a fearsome seedin’ contraption fit for the high seas?

Spoken with the spirit of a genuine sea rover, me matey, but listen here, we must band together as brethren to stand strong against the mighty organizations that threaten our way of life on the vast and treacherous ocean!

If no one seeds… then logically no one can leech. Seeding is what keeps torrents alive.

For any of this to make a difference you should disable µTP in your torrent client, or make it prefer TCP over µTP.

Just as a caveat, people disabling/throttling µTP may want to manually set appropriate global rate limits (upload/download bandwidth) otherwise it’s possible the torrent client will actually hit the maximum upload/download limits of the ISP or router forcing everything else on the network to slow down/time out during other internet usage. You’re obviously more advanced so you already know all this :)

Mainly it’s extra info for noobs messing around with their settings, often times noobs mess around with settings, disable things, etc. & then wonder why their torrent client keeps “crashing” their internet :P Making changes to µTP should be more of a last resort IMO.

µTP itself is a pretty big topic, there are a fair amount of people testing different settings in the qBittorrent / Libtorrent Github Issues but I’m not sure there’s even a consensus on a proper default setting. e.g. qBittorrent’s devs specifically chose different µTP defaults vs the Libtorrent library’s own defaults. qBittorrent defaults to having µTP enabled with preferring TCP (throttles µTP), Libtorrent defaults to having µTP enabled with peer_proportional (does not throttle µTP). The qBittorrent default is reasonable though I wonder if the Libtorrent default is the more “correct” approach but that’s certainly up to much debate. In both cases µTP is never disabled completely.

With my own testing I tend to keep settings at Libtorrent defaults just to observe behavior, with mainly private tracker peers I’ve noticed at least ~60% of my incoming connections are from µTP peers so at least for me it seems reasonable to keep it enabled.

Port forwarding allows you to bypass your NAT firewall which will naturally block all unsolicited traffic on a closed port. What that means for a torrent download is peers cannot introduce themselves to you and create a new connection, you can only connect to active peers who have their ports open.

Just to add more background to that, before your torrent can begin downloading pieces from various peers, you need to know the address of the peers sharing the pieces you need. Typically that is handled by the tracker and/or DHT. A tracker acts as sort of a logistics middle-man. It helps facilitate efficient transmission between peers by tracking what each peer has and needs. If peer B needs piece X, the tracker will supply peer B with the address to peer A who has piece X. Assuming peer A has their incoming port open, they will accept the request for piece X and send it to peer B. If their port is closed, the request will simply be denied and no traffic will be shared between the peers. The tracker’s address, as well as the data hash and some other misc data is coded into the torrent file. DHT is a little more unique and complicated. It is a fully distributed hash table on a P2P network and does not rely on a tracker at all, it’s strictly P2P. The only little catch to that is to initially introduce yourself into the network you need to bootstrap your connection using some hardcoded addresses, often from a very centralized source. Port forwarding becomes much more important for DHT because after the initial bootstrap, there is no middle-man, it’s strictly peer to peer and by having your ports closed, your client can’t effectively communicate across the network. Without two-way communication across peers, your client will generally be stuck with a very limited pool of peers it can communicate with. Magnet links as well as most torrent clients utilize DHT.

One reason it’s not so noticeable these days when ports are closed is because many torrent peers exist in big data centers with virtually unlimited bandwidth. When torrents were still young, most if not all peers were hosted on consumer grade hardware at a residence so you needed every connection you could get.

If your torrent download happens to be a well-known Linux ISO, chances are very likely that there will be at least two or three peers you’ll connect to that exist in a data center, they will most likely account for 80%+ of your download speed.

Blocking ports ultimately hurts seeding the most which can effect the overall “health” of a torrent. Say a peer labeled A can’t connect to those giant data center peers for whatever reason, they now have to seek out other peers that may have the data they are looking for. If all the other peers have their ports closed, well then the torrent is essentially dead for peer A and they’ll have to either wait for someone with open ports to come online and start seeding or search for an entirely new torrent.

Sorry, this was a bit of an on-the-go mind dump so please anyone correct me if I’m wrong anywhere here but that’s pretty much the gist of port forwarding in the context of torrenting.