Setting Up a Minimal Web Server for Logging Information with BusyBox

by

Setting Up a Minimal Web Server for Logging Information with BusyBox

Creating a simple logging server doesn’t have to be complicated. With the right tools and a minimal amount of code, you can quickly set up a system to capture and store information sent to your server. This guide walks through the process using BusyBox’s built-in HTTP daemon.

Getting Started with BusyBox

BusyBox is an excellent lightweight utility for systems with limited resources. At just 1-1.5 megabytes, it contains core tools including a web server (HTTPD) that can be easily installed on routers, modems, ARM devices, and phones.

To start the BusyBox web server, use the following command:

busybox httpd -p 3333 -f -v

The parameters are:

  • -p 3333: Sets the server port (use higher ports if 80 is already in use)
  • -f: Forces the server to run in the foreground
  • -v: Enables verbose mode to see incoming requests

Creating Basic Web Content

Once your server is running, you’ll need an index.html file in your current directory. This file will be served when someone accesses your server:

echo "Hello world" > index.html

You can enhance this file with HTML formatting as needed:

<h1>Title</h1>
Hello world

Setting Up the Logging Script

The real power comes from creating a script to capture incoming data. Follow these steps:

  1. Create a cgi-bin directory in your current folder
  2. Create a script file inside this directory (e.g., logger.cgi)
  3. Make the script executable with chmod +x logger.cgi

Here’s the minimal code needed for the logging script:

#!/bin/bash
echo "Content-type: text/html"
echo ""
cat >> ../log.text
echo >> ../log.text

This script will:

  • Tell the browser it’s receiving HTML content
  • Capture all information passed to it
  • Append this information to a log file in the parent directory
  • Add a new line after each entry for readability

Sending Data to the Server

You can send information to your logging server using various methods. One simple approach is using wget:

wget -qO- --post-data="name=john&phone=55555555" http://localhost:3333/cgi-bin/logger.cgi

You can also send custom text:

wget -qO- --post-data="The cat ran and it was fast" http://localhost:3333/cgi-bin/logger.cgi

Every request will be captured in your log.text file, with each entry on a new line.

Security Considerations

While this minimal setup works for basic logging, be aware of these security concerns:

  • The web server runs with the permissions of the user who started it
  • No encryption is used, so data is transmitted in plain text
  • No user authentication is implemented
  • Input isn’t sanitized, which could lead to security vulnerabilities

For production environments, you should consider:

  • Running the server as a limited-permission user
  • Implementing HTTPS with security certificates
  • Adding user authentication
  • Sanitizing all input data
  • Possibly using a database instead of a simple log file

This minimal approach demonstrates how little code is needed to accomplish basic logging functionality, providing a foundation you can build upon for more robust solutions.

Leave a Comment