Hacker News Reader

Comment by jiofj | Hacker News Reader

The future has always been DHT, but having no built-in search feature like Kademlia is a huge oversight imo.

There are websites that crawl DHT and you can search using them https://btdig.com but of course it would be better to have something decentralised.

View on HN

Me: What is DHT?

Also Me: Distributed hash table.

Me: Thanks.

Also Me: You're welcome, but don't be too impressed. I googled it.

DHT is a protocol that allows peers to exchange data about torrents and peers; you can download the contents of a torrent by its hash instead of having to download a .torrent file and connect to a server to find peers.

Kademlia is similar for eMule, only that it also allows search.

> you can download the contents of a torrent by its hash

How are hash collisions resolved? I'd hate to think I'm downloading my favorite TV show & find that I've downloaded something that makes ma attract the attention of law enforcement.

Aren't hash collisions supposed to be extremely unlikely in general?

Yes, but I don't want to explain to the FBI I was really trying to download a nature documentary.

It's sha1, collisions are unrealistic

Thanks, that’s the answer was looking for.

Kademlia, being a permissionless distributed search protocol, is also heavily polluted. Both by malware and people set out to make piracy harder. It's a hard problem.

Not my experience.

I love that most clients support just pasting the infohash into the 'add url' field.

Saved me a few times on shady-looking sites that demanded an account or something before showing a download link, but still listed the infohash on the page. Useful too when pasting it into a search engine actually gave results.

It was a product of the time. At the time you had the copyright trolls who would use the peer search function that was available on earlier p2p tools, and use that as the basis to blast out shakedown letters.

By removing search from the protocol it meant that they actually had to join the swarm. Also, this led to the creation of private trackers.

DHT means no central tracker to be taken down however each peer is still know when connecting and downloading. Not a problem for countries where downloading is legal but others can have a difficult time.

many VPN providers available.

There is: https://github.com/boramalper/magnetico. Working like a charm.

You also want to know which torrent looks legit, so you may want to query trackers ... Here you go: https://sr.ht/~rakoo/magneticos/

https://github.com/nbdy/dhtc ?

How do you get the DHT without at least a centralized bootstrap?

query a known (or attempt reaching a previously known) peer

Isn't that then the centralized authority?

Well, no:

- IPs of peers can be obtained from any source, not necessarily a centralized one. you could argue that this is centralized if you use only one, but there is no central authority and you can move to any other one or use a sizeable list of completely independent sources.

- torrent clients can persist previously contacted peers to contact them when starting up again from scratch, attempting connection in hopes that they are still around (which at least some usually are given that clients are usually long-running processes)

Reply on news.ycombinator.com