subfinder is a subdomain enumeration tool written in the Go programming language. Subfinder is used for discovering passive subdomains of websites by using digital sources like Censys, Chaos, Recon.dev, Shodan, Spyse, Virustotal, and many other passive online sources. Subfinder is widely used by Ethical Hackers and Bug bounty hunters in the Information gathering Phase which is also known as Reconnaissance.
As subfinder is a Go tool you need to have the Go language package installed before installing subfinder.
1. From Source(Recommended)
All you need to do is open your terminal and paste this one line of code and press enter.
GO111MODULE=on go get -v github.com/projectdiscovery/subfinder/v2/cmd/subfinder
2. From Binary
Firstly download the release suitable for your OS from https://github.com/projectdiscovery/subfinder/releases/ and then unzip the folder and move the subfinder binary file to /usr/local/bin/ and you are good to go
# download release from https://github.com/projectdiscovery/subfinder/releases/ tar -xzvf subfinder-linux-amd64.tar.gz mv subfinder /usr/local/bin/ subfinder -h
3. From Github
Clone https://github.com/projectdiscovery/subfinder.git repository and change directory to subfinder/v2/cmd/subfinder and then type go build . (don’t forget to put a ‘.’ at the end ) now move the subfinder binary file to /usr/local/bin and subfinder is ready to use.
git clone https://github.com/projectdiscovery/subfinder.git cd subfinder/v2/cmd/subfinder go build . mv subfinder /usr/local/bin/ subfinder -h
Retrieving the Subfinder list of attributes
Working with SubFinder
Here we will find out subdomains of the domain geeksforgeeks.org and setting a concurrency of 50. I got around 73 subdomains for geeksforgeeks.org in 4 seconds 71 milliseconds.
subfinder -d geeksforgeeks.org -silent -t 50
Pros of subfinder over sublist3r: As subfinder is a Go Tool and sublist3r is a python tool and Go Language is faster than python and also Go language’s approach to concurrency is very easy to work with. Also, subfinder also provides various options that sublist3r doesn’t.