Many people report receiving notifications from their ISPs after downloading files using torrents. How will your ISP know? It’s all about how BitTorrent works. BitTorrent is much less anonymous than it might seem at first glance.
How do torrents work?
Downloading over the Internet involves receiving data from a remote server. Other than the initial request you send to get a file, most downloads are a one-way street. You get data from a central server and you don’t have to send anything from your server. Loading web pages, watching videos online, and downloading games on Steam all work this way.
However, if you download too many IP addresses from the same server at the same time, this can lead to clogging and slow download speeds.
Torrents are different from typical Internet downloads because they follow a peer-to-peer protocol. A swarming torrent is a group of IP addresses simultaneously downloading and uploading a file. Instead of just downloading a file from some server, you also download parts of it to other people. Because of this constant exchange process, the file associated with a torrent often downloads significantly faster than a standard download.
BitTorrent is often used for piracy. However, there are many legitimate ways to use a torrent. Because they can be paused, resumed, and split into smaller parts, they are ideal for downloading large files such as games, software, plugin packages, and updates. They are also a common method for distributing free music and videos.
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What does your ISP see?
Your ISP can’t immediately tell if you’re using BitTorrent, and can’t tell you what you’re downloading from it. Most torrent clients have some form of encryption that makes it hard for ISPs (and your home router) to identify this BitTorrent traffic. However, there are several ways to know that you are using BitTorrent to download something.
Downloading torrents exhibits some very obvious usage patterns such as multiple simultaneous download streams and many different TCP (Transmission Control Protocol) connections because you are talking to many IP addresses at the same time. If your ISP is actively trying to detect torrent usage, they will most likely be able to detect it.
Another way they can do this is by contracting with third parties to monitor groups of torrenters and see if the IP address below them shows up in that swarm’s user list.
However, most ISPs have no interest in preventing you from using torrents. The main reason they will pay attention is that torrents consume a lot of bandwidth, but with the rise of high-speed wired connections, this is less of an issue than it used to be. However, some ISPs, such as WiFi ISPs and mobile networks, may throttle (slow down) your connection if you download large files using torrents.
Media companies and copyrighted files
So if ISPs don’t care that you use their service to download files using BitTorrent, why do people get emails telling them to stop using it?
If you are downloading a torrent, you can see every IP address you are connected to. This is why many media companies and major rights holders are joining the genus of popular torrents of their content that has been pirated. They then extract the lists of IP addresses they know are downloading the file and sort those lists by ISP.
They can then send notifications to ISPs that those IPs below them are downloading pirated material. Your ISP then sends you a notification saying they know you are using BitTorrent and asking you to stop pirating. If you repeatedly do this, your internet may be disconnected or worse; the copyright owner can sue you. This is especially true if a media conglomerate owns your ISP.
There is little to no risk of receiving one of these emails as long as all the content you download via torrents is legal. Many legitimate software launchers use the torrent protocol to speed up the download of software updates.
Do VPNs hide my torrent usage?
VPNs or virtual private networks allow you to remotely connect to another network. When you connect to a VPN, your IP address and location are hidden behind the network you are connected to. Many people use a VPN to browse the Internet more securely or to access content that is region-specific.
When you download a torrent through a VPN, it looks like the new IP address is the peer. However, not all VPNs are created equal. Free VPNs are usually very slow and have incompatible connections, making them unreliable for downloading large files. A paid VPN offers much better security, and speeds are often close to your actual internet connection plan.
It should also be noted that for most BitTorrent clients, torrents continue to download or «fill up» even after the file download is complete. If you disconnect from your VPN before stopping the torrent from filling up, your actual IP address may appear in the peer list.