Tiny Robots WAF

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A minimal web application firewall plug used by Tiny Robots apps. It halts vulnerability-scanner requests with a plain 404 Not Found before they reach the Phoenix router, so probes like /.env and /wp-login.php never hit session/parser plugs, never raise Phoenix.Router.NoRouteError, and never create error-reporting noise.

What it blocks

  • Path segments that are not valid UTF-8 or contain a null byte
  • Dot segments such as /.env, /.git/config, /foo/.env — /.well-known/* is allowed
  • Segments with extensions an Elixir app never serves: .php, .php5, .php7, .phtml, .asp, .aspx, .jsp, .jspx, .cgi
  • Paths whose first segment is wp-*, wordpress, phpmyadmin, or cgi-bin (case-insensitive)

It is deliberately stateless: no IP tracking, no rate limiting, no logging. Blocked requests are simply answered early and cheaply.

Installation

def deps do
  [
    {:rbtz_waf, "~> 0.1"}
  ]
end

Usage

Put the plug early in your endpoint, before Plug.Parsers and Plug.Session:

defmodule MyAppWeb.Endpoint do
  use Phoenix.Endpoint, otp_app: :my_app

  # ...
  plug Plug.RequestId
  plug Rbtz.WAF
  # ...
  plug MyAppWeb.Router
end

Options

  • :allow_prefixes — first path segments exempt from the scanner rules, for routes that legitimately serve arbitrary external paths (the encoding rules still apply):
plug Rbtz.WAF, allow_prefixes: ["proxy"]

License

MIT — see LICENSE.