4 ms·

How would that work for malicious nodes in a distributed network? A torrent will be DoSed if there are 10,000 leechers for every seeder.

• killin_dan 10y ago
  Just set your peer limit to a small number. Your client shouldn't be connected to more than a couple peers at a time, and the tracker should be able to make sure you can find good peers.
• tw04 10y ago
  The same way private trackers already work. You don't seed, you quickly get banned.
• the8472 10y ago
  you are assuming that torrents only work when there are seeders, but that's not true at all. Seeders simply provide surplus bandwidth, allowing a torrent to operate on altruism. In the worst case where almost everyone is downloading it degrades into tit-for-tat behavior where everyone gets as much as others are willing to provide based on their current contribution, which still scales with the number of downloaders. Maybe I should have mentioned one other condition. The network must be distributed and consist of nodes with symmetric bandwidth. If you have symmetric bandwidth you can upload as fast as you download and thus on average the network won't need altruistic nodes to saturate everyone's downlink. We could go even further and demand ISP-local source-specific multicast, then you would have massive bandwidth multiplication for uploaders, making it trivial to replicate popular content. Alas, that seems to be a pipe dream.
  • x1798DE 10y ago
    > you are assuming that torrents only work when there are seeders, but that's not true at all. No, I'm saying that if someone is trying to DDoS your torrent, the bandwidth doesn't scale with the number of downloaders because all the malicious nodes are using download bandwidth but (deliberately) not providing upload bandwidth. I was playing a bit fast and loose with the term "leecher" (I meant someone downloading but <i>not uploading at all</i>, as opposed to active participants in the swarm), but I thought that was understood. Even if you had a system where people were prioritized based on how much they were sharing, there are a lot of ways to get around that protocol with a big enough botnet. Don't get me wrong, the built-in scaling features of things like torrents are great, I'm just saying I don't see an easy way for it to solve DDoS because it relies on cooperation from the participants.
    • the8472 10y ago
      Well, that depends on what kind of ddos we're talking about. The primitive ones simply pick a server and flood it with some kind of request. The distributed part makes it harder to block and provides more bandwidth than most single points can take If you make your content distributed it can be mirrored by many more nodes than are needed to satisfy demand, removing some of the asymmetry while also making it more difficult for the attacker to pick his targets. Note that p2p networks can also respond to demand. E.g. in torrents clients don't seed all the content they have all the time, they first check statistics which swarms could use the bandwidth most. So if there were some content under attack by fake downloaders it would look like a swarm in need of extra bandwidth and thus more real nodes would join it to serve content, thus making the attack more costly. > Even if you had a system where people were prioritized based on how much they were sharing, there are a lot of ways to get around that protocol with a big enough botnet. With a big enough botnet you can also take out any ddos protection service.
    • user5994461 10y ago
      The P2P protocols are penalizing leechers. Or to be accurate, your client is giving priority (for you to upload) to people who are uploading contents to you.
    • nebabyte 10y ago
      > because all the malicious nodes are using download bandwidth but (deliberately) not providing upload bandwidth And avoiding being throtted how?