Subdomain Scanner using Bash and the crt.sh API

This script is an automated subdomain scanner that uses public data from the crt.sh API to search for subdomains of a given domain. Equipped with parallel search, connectivity checking, and email notification features, this script helps pentesters or security administrators find and verify subdomains quickly and efficiently.

Key Features:

• Unique subdomain search using crt.sh API.
• Connectivity check in parallel with ping.
• Automatic output to file and statistics of results.
• Retry handling and error logging.
• Email notification (optional) for scan results.
• Automatic subdomain search via crt.sh API.
• Filtering unique subdomains to avoid duplication.
• Output to a neatly formattedfile.
• Automatic logging to keep a log of each execution.
• Connectivity check (ping) to make sure the subdomain is active or not.
• Warning notification if the domain or subdomain is not found.
• Argument parsing to allow the use of arguments from the command line.

Explanation of New Features:

1. Parallel Execution:We use parallel to run the ping command simultaneously for up to 10 subdomains at a time. This improves performance if there are many subdomains to scan.
2. Retry Handling:The --retry 3 option on the curl command ensures the request is repeated up to 3 times in case of failure.
3. Execution Time Statistics:The script records the start time and end time to provide information on how long the scanning process took.
4. Email Delivery (Optional):Users can add an email address as the second argument to receive the scan results via email. If the address is not provided, this feature is skipped.
5. Dependency Handling:The script checks for the presence of all required tools: curl, jq, xargs, parallel, and mail. If one is not found, the script stops and gives an error message.

Installation Steps

Clone Repository from GitHubFirst, make sure you have Git on your system. If not, install Git:

sudo apt update && sudo apt install git -y

Clone project repository from GitHub:

git clone https://github.com/lamcodeofpwnosec/subdomain-scanner.git
cd subdomain-scanner

Make sure Dependencies are Installed This script requires several tools: curl, jq, parallel, and mail. Install all these tools using the following command:

sudo apt update
sudo apt install curl jq parallel mailutils -y

Grant Execution Permission to Scripts Change the access rights so that the script can be executed:

chmod +x subdomain_scanner.sh

Usage of features

Run without Email Notification To run the script without sending the results via email:

./subdomain_scanner.sh contoh.com

Run with Email Notification Run by sending the scan results to email (for example: email@example.com):

./subdomain_scanner.sh contoh.com email@example.com

Help Options If you want to see how to use:

./subdomain_scanner.sh

Explanation of Generated Output Files

Subdomain List file Contains a list of unique subdomains found from crt.sh:

$ cat contoh.com_subdomains.txt

www.contoh.com
mail.contoh.com
api.contoh.com

Connectivity Result File Contains subdomains that are on or off after being checked with ping:

$ connectivity_result.txt

[LIVE] www.contoh.com
[DEAD] api.contoh.com
[LIVE] mail.contoh.com

Terminal Statistics Once the scan is complete, you will see a summary like this:

=====================================
     Advanced Subdomain Scanner
=====================================
[+] Memulai pencarian subdomain untuk: contoh.com
[+] Ditemukan 5 subdomain untuk contoh.com.
[+] Memeriksa konektivitas subdomain secara paralel...
[+] 3 subdomain aktif dan 2 subdomain tidak aktif.
[+] Pemindaian selesai dalam waktu 8 detik.

Conclusion

With these steps, you can easily:

• Install dependencies and run scripts.
• Perform an automated subdomain scan.
• Save results into a file and check connectivity status.
• Send reports via email for more effective monitoring.

This script is perfect for testers and administrators to enumerate subdomains efficiently. 🚀

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