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Slowloris for nginx DoS. Written in go

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Statistics on goloris

Number of watchers on Github 158
Number of open issues 3
Main language Go
Average time to merge a PR 12 days
Open pull requests 4+
Closed pull requests 0+
Last commit over 3 years ago
Repo Created about 6 years ago
Repo Last Updated almost 2 years ago
Size 23 KB
Organization / Authorvalyala
Page Updated
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Goloris - slowloris[1] for nginx DoS


  • Features

    • Uses as low network bandwidth as possible.
    • Low CPU and memory usage.
    • Automatically and silently eats all the available TCP connections to the server.
    • Supports https.
    • Easily hackable thanks to clear and concise Go syntax and powerful Golang features.
  • Limitations

    • Can eat up to 64K TCP connections from a single IP due to TCP limitations. Just use proxies if you want overcoming this limitation :)
  • How it works?

It tries occupying and keeping busy as much tcp connections to the victim as possible by using as low network bandwidth as possible. If goloris is lucky enough, then eventually it should eat all the available connections to the victim, so no other client could connect to it. See the source code for more insights.

  • How quickly it can take down unprotected nginx with default settings?

In a few minutes with default config options.

  • Which versions of nginx are vulnerable?

All up to 1.5.9 if unprotected as described below (i.e. with default config).

  • How to protect nginx against goloris?

I know the following options:

  • Limit the number of simultaneous TCP connections from the same source ip. See, for example, connlimit in iptables or
  • Deny POST requests.
  • Patch nginx, so it drops connection if the client sends POST body at very slow rate.

    • How to use it?
go get -u -a
go build
./goloris -help

P.S. Don't forget adjusting ulimit -n before experimenting.

And remember - goloris is published for educational purposes only.


goloris open pull requests (View All Pulls)
  • Error check DialWorkersCount
  • Fix readme problem
  • fix block formatting
  • Fixed formatting in
goloris list of languages used
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