What is Slowloris?

Slowloris is basically an HTTP Denial of Service attack that affects threaded servers. It works like this:

  1. We start making lots of HTTP requests.
  2. We send headers periodically (every ~15 seconds) to keep the connections open.
  3. We never close the connection unless the server does so. If the server closes a connection, we create a new one keep doing the same thing.

This exhausts the servers thread pool and the server can’t reply to other people.

How to install and run?

You can clone the git repo or install using pip. Here’s how you run it.

  • sudo pip3 install slowloris
  • slowloris

That’s all it takes to install and run

If you want to clone using git instead of pip, here’s how you do it.

  • git clone
  • python3

SOCKS5 proxy support

However, if you plan on using the -x option in order to use a SOCKS5 proxy for connecting instead of a direct connection over your IP address, you will need to install the PySocks library (or any other implementation of the socks library) as well. PySocks is a fork from SocksiPy by GitHub user @Anorov and can easily be installed by adding PySocks to the pip command above or running it again like so:

  • sudo pip3 install PySocks

You can then use the -x option to activate SOCKS5 support and the --proxy-host and --proxy-port option to specify the SOCKS5 proxy host and its port, if they are different from the standard

Configuration options

It is possible to modify the behaviour of slowloris with command-line
arguments. In order to get an up-to-date help document, just run
slowloris -h.

  • -p, –port
    • Port of webserver, usually 80
  • -s, –sockets
    • Number of sockets to use in the test
  • -v, –verbose
    • Increases logging (output on terminal)
  • -ua, –randuseragents
    • Randomizes user-agents with each request
  • -x, –useproxy
    • Use a SOCKS5 proxy for connecting
  • –https
    • Use HTTPS for the requests
  • –sleeptime
    • Time to sleep between each header sent


The code is licensed under the MIT License.


View Github