Others have summarized it well but I'll add my perspective also.
I2P is a decentralized network of peers. All traffic gets routed through multiple peers before reaching its destination. Traffic is also encrypted by multiple layers of encryption and each connected peer can only decrypt one layer, that layer will only contain further routing info so that peer knows the next place to hand off your data. The encryption gets stripped layer by layer until it finally reaches its destination.
What this ultimately means is that by interacting with a website or service through I2P it is virtually impossible to identify any information the user is sending or receiving and it is also impossible to tell where the connections are going or coming from.
To make things even more interesting all I2P routers by default also contribute resources back into the network so while your I2P Router is handling your communication connections, it's also volunteering to be a connection node in someone else's connection. This adds further security because now you've got many Peer to Peer connections going in and out of your network, all encrypted so any prying eyes will have an exceedingly difficult time trying to make sense of any of your internet traffic.
Tor relies on the good faith of its community to contribute resources to the network and it's not very well incentivised causing its resources to be far more limited and bogged down. For this reason, Tor cannot sustain heavy torrent traffic without easily being overwhelmed. In I2P, every user is a contributor so the more people who use I2P, the faster and better it becomes.
The big advantage Tor has over I2P are outproxies and the beautifully prepacked Tor Browser. Tor has a lot more influence and money backing it so there are some large and well protected entities that can afford all the legal trouble that outproxies can bring. Unfortunately there just isn't enough money or legal support in the I2P community to reliably support outproxies even though I2P already has full support for it.
I2P is a fantastic tool for private communication across the Internet and the true ELI5 here is I2P natively supports "anonymous" torrenting (even encouraged it as it strengthens the network further) and will do so privately and securely without any need for a VPN. Adding support to QBittorrent makes it even easier to access I2P torrenting with very minimal set up required.
The only catch here is you can't go around downloading any old torrent from the Internet on I2P, someone needs to actually be seeding that torrent on the I2P network for you to get any data. There are fully functioning tracker sites exclusively within I2P that have a huge catalog of content but all is not lost for "clearnet" torrents either. Software like BiglyBT and now QBittorrent, allows users to "bridge" or "cross seed" torrents across the two networks, that way content is shared no matter what network you're a part of.
BiglyBT has been doing this for a while now but I'm so happy to see QBittorrent finally embracing this as well.
EDIT: https://geti2p.net/en/
Cooler and less cool because no exit nodes. It's fully separate from normal internet.
To summarise, I2P is similar to Tor, except that every client also serves as a node, and there are no exit nodes, so you can only access data shared by other I2P clients
Is my summary correct?
Took a quick look at the first few messages and the links: seems like BiglyBT is banned by a lot of private trackers because it's possible to mod it to spoof the numbers required to stay a member in the private tracker, while also being able to create a torrent file that allows others using the mod to utilize the private tracker without permission. Not sure if any of that functionality has to do with I2P.
Would that not be possible in every other client? Or is it just the easiest to do with BiglyBT?
Thanks for such a detailed answer! How does the I2P speeds compare to running torrents over VPN? I assume its a lot slower?
It varies wildly between torrents based on activity of the torrent and your I2P tunnel settings. Participation on I2P torrents is definitely significantly lower than normal clearnet torrents (at the moment) so a lot of times there are only 1-2 peers available which often results in roughly 35-60 KB/s but I've also seen some more popular torrents download at nearly 1 MB/s. I2P can self update from a torrent, that file generally has high participation, and on average, downloads at speeds above 150 KB/s. There definitely is some bandwidth lost just due to overhead of running the network, fewer hops and more tunnels helps with that though. I usually run about 10 tunnels with Snark, all with 3 hops. If I reduce that to two hops I can still have good privacy but with significantly less bandwidth overhead, I just personally feel the extra privacy of three hops is worth the sacrifice.
Speed and bandwidth rely heavily on the level of participation, more high-bandwidth peers torrenting over I2P will significantly speed things up. With my current setup, my router pushes around 450 KB/s on average just for participating traffic (traffic that is only contributing to other I2P peers) so it's definitely capable of comparable speeds to that of a VPN.
Oh and I should have mentioned this before, torrenting over I2P also helps strengthen your connection to the I2P network because it introduces you to more high-speed peers to communicate with. Really speeds things up if you're trying to bootstrap a new I2P router
I2P has quite a few internal torrents with large swarm sizes that you can stress test pretty reasonably with. Another fun thing you can try if you are using I2P Snark (java I2P built-in torrent handler), you can paste magnet links from the clearnet into your client and if you're lucky some beautiful people out there are cross seeding that torrent and it'll allow you to take part in downloading clearnet torrents over I2P.
So, if I set up an I2P router on my network and use Qbittorrent, would it theoretically be possible to contribute to I2P using the torrents that I already seed? Or is it not that easy?
You can cross-seed torrents by adding I2P trackers to the tracker list. What helps is when you upload the .torrent file to tracker2.postman.i2p (the only? i2p public torrent tracker) so that others can find the magnet/torrent link and start downloading. That way people can find the InfoHash and also have trackers embedded in the i2p .torrent file to allow you to find seeders.
Some info on this subject: https://old.reddit.com/r/i2p/comments/xfqvap/how_to_correctly_cross_seed_to_make_clearnet/
What I mean is if I create a new torrent of Big Buck Bunny with a InfoHash of b1946ac92492d2347c6235b4d2611184 for example, no one will find my torrent by searching for "Big Buck Bunny". Unless I post this hash somewhere, advertising "Hey, this torrent is Big Buck Bunny" like what 1337x and other torrent sites do, you won't "find" it. Basically, we have to use a torrent indexer like tracker2.postman.i2p to search the metadata and find torrents we want. If that makes sense.
I2P router means the I2P software on your computer. You don't have to buy a new router.
From my experience, some popular I2P torrents have gotten up to 1 MB/s download, but I usually average around 200 KB/s. While it is not blazing fast, it does provide a good deal of anonymity for everyone involved with the torrent.
Also, you can lower the anonymity and increase speeds by reducing the number of hops from 3 to 2 or 1. You can choose how "anonymous" you'd like to be while torrenting, at the cost of speed.
How are nodes chosen by the client?
What stops governments/LEO/copyright dragons from spinning up thousands of the fastest/most accessable i2p nodes so that clients connect to them first, then these hosts log the traffic paths to identify origin/destination?
https://geti2p.net/en/docs/how/threat-model#sybil
Good write-up from the I2P team on this topic. Page includes other attack vectors as well.
All traffic gets routed through multiple peers before reaching its destination
From the article that was posted:
The main new feature is support for I2P, the Invisble Internet Project. It uses a fully encrypted privacy network layer to hide user activity and locations. The network does not use servers. Peers contributed "a portion of their resources" to other network particpants.
The maintainers promise that "non one can see where traffic is coming from, where it is going, or what the contents are" when the Invisible Internet Project is active.
Private trackers see your ratio because your client tells it to them. If you cheat, you get banned. They can tell you cheat because the seeder reports upload but you don't report download. You must not use private tracker torrents except on their tracker because it looks like cheating because the other client isn't connected to their tracker, and you will get banned.
Maybe I'm a smooth brain - but I always thought private trackers were kept private/exclusive as a way of promoting seeding - the exclusivity of private trackers lowers risk/fear of seeding, so people seed, files are kept alive. - the ratios are a stick to enforce the rules and boot leechers. Centralizing seed logs with private trackers always gave me the creeps though.
Honestly, it sounds like there's essentially no risk of seeding on I2P. Wouldn't more people be willing to seed in general? And wouldn't that in turn obviate the need for private trackers?
Alas, perhaps my smooth brain brings naivety along with it.
This is a good point. I also feel like private trackers are meant for people who actually seed content they download, and just have good intentions to help share content. This also comes with hardware requirements (disk space) sometimes that not everyone has.
Private trackers promote seeding, but people don't seed for more reasons than getting caught. Public trackers are leechfests. Some of my public torrents, I have ratio 30 and I'm still the only seeder. Why should I bother with this, if nobody else will? I should put the torrent on a private tracker where other people will help spread it, and stop public seeding.
If it doesn't use servers, where is the content stored? Or stuff just disappears when a user whose computer used to serve the files is turned off?
It's BitTorrent. There are seeders.
I2P has servers to run websites, but they mean I2P itself has no central servers that control it, like Tor does.
It's a dark network. Instead of going to a website, you go to an "eepsite", and to get there you securely route through a bunch of random computers (as if you went through 10+ VPNs). It's similar to Tor, but the main difference Tor's primary goal is to visit websites (on Tor, "onion sites" exist, but unlike I2P, "onion sites" are not the primary focus of Tor).
the tor onion network. But no exits to clearnet.
Everybody contributes bandwith. And because everybody contributes bandwith, privacy is created because you can never know if you reached the end of the chain and found the creator of the first network request.
In theory it's a lot more secure than the tor network. In practice it gets 1/100th of the funding, because you have to be a computer nerd to even install it, need a computer to keep it running 24/7 (longer you run, more privacy) , while tor browser "Just works" and can start providing privacy to everybody right away.
Some documentation would be nice.
I've been trying to connect qbittorrent to my local i2pd node for the last 30 minutes and for the life of me I cannot get it to work, even though other services work via SAM in the same port. Everything just times out.
Edit: for anyone else struggling, you need to add your own trackers: https://old.reddit.com/r/qBittorrent/comments/13xmr84/tutorial_how_to_use_i2p_in_qbittorrent/
qbittorrent doesn't seem to be able to fetch those on its own yet
It is experimental indeed. While it "works", it is no where near the reliability and efficiency of other I2P torrent clients like I2Psnark or BiglyBT, both of which are Java based.
Guide for Linux: https://strict3443.codeberg.page/i2p-info/hugo/public/posts/how-to-use-i2p-on-qbittorrent-nox/
You can install i2pd with sudo apt install i2pd and then point your services towards your i2p router (Ex. 127.0.0.1) and you are good to go.
Thanks! And just so I understand this correctly, do I need a separate router for this + my normal router?
You can use one i2pd router for many clients/services, as long as your device can handle it.
Probably not. I2P doesn't connect to the clearnet like Tor does, it only works if the destination is on I2P as well.
I2P does connect to the clearnet, it just doesn't by default.
Outproxies are available and you can even host your own routing it through Tor. That way you get the best of both networks.
It requires running additional software, a so called "I2P router".
This can be ran on Linux and Windows systems too, on localhost or for your local network.
Is a torrent client behind i2p as reachable as if I had a VPN with port forwarding?
EDIT: is the use of i2p compatible with private trackers? So that they can keep track of what I'm seeding?
I think I'm answering myself as I just read i2p is closed from clearnet. So I suppose the private tracker would need to be connected to i2p.
Yup, unless you specifically set it to use one of the few outproxies then it's by default just for connecting to other peers within the I2P network
I don't believe 4.6 is available yet for -nox version (headless) on ubuntu? I don't see any update in apt update.
