unperson [he/him]

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Joined 4 years ago
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Cake day: July 28th, 2020

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  • The big problem with disabling µTP is that because it uses UDP, under some kinds of NAT you can get incoming connections despite being NATted. So you will loose some peers if you’re behind a NAT. If you’re not NATted there’s no connectability advantage, because every client that implements µTP can fall back to TCP.

    The big advantage to disabling it that you can tweak these things. I don’t know of any client that lets you choose which congestion control algorithm that µTP uses. They all use one called LEDBAT that’s one of the first attempts to design one that avoids “bufferbloat”, i.e. that problem where the torrents fill up the buffers in routers and “clog up the Internet”. That’s nice however it doesn’t work well with networks with a lot of jitter like wi-fi, and it “loses” to algorithms that do fill up the buffer like the default TCP CUBIC. BBR avoids bufferbloat and is designed to keep working well with high jitter—Google’s intention was to make YouTube load faster on mobile phones. It also it wins over CUBIC, which is why almost every seedbox comes configured with no µTP and BBR congestion control. However, because it wins over CUBIC it will “clog up the Internet” in a different way: you may get lower speeds on everything else but don’t lose interactivity.

    Linux comes with a different version of BBR that’s tuned to always yield to other traffic called lp. You enable it with net.ipv4.tcp_congestion_control = lp. I think lp is the optimal choice for seeding public torrents: you give full speed to faraway peers, but only when there’s nobody else that can do it.


  • There are two low level tricks that make a huge difference for seeding, even if you can’t open ports. These are generic Linux tweaks, you may have to adapt them for QNAP depending on how customized it is. Ask me if you need help. As far as I can tell you need to ssh to the “admin” acount, so open a command line and type ssh admin@your-nas.

    To make both tweaks permanent you need to edit /etc/sysctl.conf. you can try editing them with nano. If you don’t have nano you’ll have to try with vi, but vi is not intuitive at all to use.

    nano /etc/sysctl.conf
    
    • The first tweak makes you a lot more effective to peers that are on unstable connections and on wi-fi. Google uses it for most of their infrastructure, originally on YouTube. You can read their article for more info on how it works.

      Add this line to /etc/sysctl.conf, close nano with ctrl-X, and reboot:

      net.ipv4.tcp_congestion_control = bbr
      
    • The second tweak decides how fast you can upload to people far away from you. If you calculate 2 * this value / your latency to them, you get the max speed you can upload to them. For simplicity I set it to be the same as my upload speed: let’s say you have 10 MB/s upload, that’s 10000000 bytes / second:

      Add this line to /etc/sysctl.conf, close nano with ctrl-X, and reboot:

      net.core.wmem_max = 10000000
      

      This way even someone in Australia with 500 ms of latency can download at 10 MB/s from you, (2 * 10000000 bytes / 0.500s = 10 MB/s)

    After rebooting you can check if the setting stuck with the command sysctl net.ipv4.tcp_congestion_control and sysctl net.core.wmem_max respectively.

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

    To me it makes an enormous difference, from barely any upload at all to 100 GB per day. And I’m sure it’s nice for whoever is downloading on the other side to get what they’re looking for super fast.


  • unperson [he/him]@hexbear.nettomain@midwest.socialWhat's the deal with Hexbear?
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    1 year ago

    They won’t just roll with it, awwwyissss thinks there’s an immutable “human nature” and that communism is not “compatible” with it. They think communism is anti-human, while they do not judge the current system as anti-human: it’s easy to see the little they would do of any political impact will only serve to keep the current barbarity going.