Introduction:

subfinder is a subdomain discovery tool that returns valid subdomains for websites, using passive online sources. It has a simple, modular architecture and is optimized for speed. subfinder is built for doing one thing only - passive subdomain enumeration, and it does that very well. (https://github.com/projectdiscovery/subfinder)

Installation:

1. Locate https://github.com/projectdiscovery/subfinder

2. Open terminal

3. Enter the following command:

    go install -v github.com/projectdiscovery/subfinder/v2/cmd/subfinder@latest
   

Usage:

1. -h

   This is the most common tag that is used to display all the available options which can be used with the tool.

subfinder -h

1. -d

   It is used to specify the domain name or website

subfinder -d google.com

1. -dL

   It is used to specify the list of domains contained in a file

subfinder -dL domain_list.txt
#domain_list contains all the domains.

1. -s

   It is used to specify the source to fetch the subdomains

subfinder -s github

1. -all

   It is used to search subdomains from all sources ( note: takes more time)

subfinder -d google.com -all

1. -es

   It is used to exclude the source to fetch subdomains

subfinder -d google.com -es

1. -rl

   It is used to specify the number of HTTP requests per second

subfinder -d google.com -rl <any_number>

1. -timeout

   It is used to specify the number of seconds before timing out

subfinder -d google.com -timeout <any_number>

1. -o

   It specifies the file to append the output

subfinder -d google.com -o output.txt

1. -oJ

   It specifies the target output file, but the result will be in JSON format

subfinder -d google.com -oJ output_in_json.txt

These are the top 10 flags used in the subfinder tool

Other flags

Explore other flags using the -h flag.

Want more subdomains?

Non - configured subfinder will yield fewer subdomains only !!!

1. Locate $HOME/.config/subfinder/provider-config.yaml

   &

2. Locate $HOME/.config/subfinder/config.yaml

Configure these .yaml files with your API keys.

Happy Learning. Cheers🙌❤️