Subsystem

To create a program in Go that scans for subsystems (e.g., PHP, Python, or other technologies running on a web server), you need to create a few files: main.go for the main logic, and optionally, a server.go file for the scanning functionality. Here is a step-by-step guide:

Step 1: Initialize the Go Module

First, create a new directory for your project and initialize the Go module.

mkdir subsystem
cd subsystem
mkdir lib
go mod init github.com/username/subsystem

Step 2: Create the `subsystem.go` File

Create a lib/server.go file to handle the functionality of identifying subsystems.

package lib

import (
	"fmt"
	"net/http"
	"strings"
)

// GetServerInfo fetches the headers of the given URL and tries to identify the server and its version.
func GetServerInfo(url string) {
	// Ensure the URL starts with http:// or https://
	if !strings.HasPrefix(url, "http://") && !strings.HasPrefix(url, "https://") {
		url = "http://" + url
	}

	resp, err := http.Get(url)
	if err != nil {
		fmt.Printf("Error fetching URL %s: %v\n", url, err)
		return
	}
	defer resp.Body.Close()

	fmt.Printf("Headers for %s:\n", url)
	for key, values := range resp.Header {
		for _, value := range values {
			fmt.Printf("%s: %s\n", key, value)
		}
	}

	// Try to extract specific information
	server := resp.Header.Get("Server")
	if server != "" {
		fmt.Printf("\nDetected Server: %s\n", server)
	} else {
		fmt.Println("\nServer information not found in headers.")
	}

	xPoweredBy := resp.Header.Get("X-Powered-By")
	if xPoweredBy != "" {
		fmt.Printf("Detected Subsystem (e.g., PHP, Python): %s\n", xPoweredBy)
	} else {
		fmt.Println("Subsystem information not found in headers.")
	}
}

Step 3: Create the `main.go` File

Create a main.go file to use the subsystem scanning functionality.

package main

import (
	"fmt"
	"os"

	"github.com/username/subsystem/lib"
)

func main() {
	var url string

	if len(os.Args) > 1 {
		url = os.Args[1]
	} else {
		fmt.Print("Enter the URL (e.g., example.com): ")
		fmt.Scanln(&url)
	}

	lib.GetServerInfo(url)
}

Step 4: Run the Program

Run the program using the go run command.

go run main.go example.com

The program will fetch the headers from the specified URL and attempt to detect:

The subsystem (e.g., PHP, Python) using the X-Powered-By header.
The web server software using the Server header.

Example Output

For a server running Apache with PHP:

Headers for http://example.com:
Server: Apache/2.4.41 (Ubuntu)
X-Powered-By: PHP/7.4.3
...

Detected Server: Apache/2.4.41 (Ubuntu)
Detected Subsystem (e.g., PHP, Python): PHP/7.4.3

Notes

This program relies on the headers provided by the server. If the server suppresses or obfuscates headers for security reasons, detection may be limited.
The program can be extended to include fingerprinting techniques for more detailed subsystem identification.

Last modified: 08 January 2025