Subfinder

Subfinder provides a wide range of flags to control input, sources, filtering, rate-limiting, and output formats. Use subfinder -h to view the full help menu.

Usage:
  ./subfinder [flags]

Flags:
INPUT:
  -d, -domain string[]  domains to find subdomains for
  -dL, -list string     file containing list of domains for subdomain discovery

SOURCE:
  -s, -sources string[]           specific sources to use for discovery (-s crtsh,github). Use -ls to display all available sources.
  -recursive                      use only sources that can handle subdomains recursively (e.g. subdomain.domain.tld vs domain.tld)
  -all                            use all sources for enumeration (slow)
  -es, -exclude-sources string[]  sources to exclude from enumeration (-es alienvault,zoomeyeapi)

FILTER:
  -m, -match string[]   subdomain or list of subdomain to match (file or comma separated)
  -f, -filter string[]   subdomain or list of subdomain to filter (file or comma separated)

RATE-LIMIT:
  -rl, -rate-limit int  maximum number of http requests to send per second
  -rls value            maximum number of http requests to send per second for providers in key=value format (-rls "hackertarget=10/s,shodan=15/s")
  -t int                number of concurrent goroutines for resolving (-active only) (default 10)

UPDATE:
  -up, -update                 update subfinder to latest version
  -duc, -disable-update-check  disable automatic subfinder update check

OUTPUT:
  -o, -output string       file to write output to
  -oJ, -json               write output in JSONL(ines) format
  -oD, -output-dir string  directory to write output (-dL only)
  -cs, -collect-sources    include all sources in the output (-json only)
  -oI, -ip                 include host IP in output (-active only)

CONFIGURATION:
  -config string                flag config file (default "$CONFIG/subfinder/config.yaml")
  -pc, -provider-config string  provider config file (default "$CONFIG/subfinder/provider-config.yaml")
  -r string[]                   comma separated list of resolvers to use
  -rL, -rlist string            file containing list of resolvers to use
  -nW, -active                  display active subdomains only
  -proxy string                 http proxy to use with subfinder
  -ei, -exclude-ip              exclude IPs from the list of domains
  -mr, -max-results int         limit the number of results per source (0 = unlimited; honored by paginating sources)

DEBUG:
  -silent             show only subdomains in output
  -version            show version of subfinder
  -v                  show verbose output
  -nc, -no-color      disable color in output
  -ls, -list-sources  list all available sources (-oJ for JSON)

OPTIMIZATION:
  -timeout int                  seconds to wait before timing out (default 30)
  -max-time int                 minutes to wait for enumeration results (default 10)
  -rsr, -response-size-read int max response body size to read in bytes from passive sources (0 = unlimited)

Developers can integrate Subfinder's enumeration capabilities into their own Go applications by using the pkg/runner package. The core workflow involves:

1. Parsing options using runner.ParseOptions().
2. Initializing a new runner instance with runner.NewRunner(options).
3. Executing the enumeration via newRunner.RunEnumeration().

Note: The runner attempts to increase OS file descriptors automatically via the fdmax package to handle high concurrency.

package main

import (
	"github.com/projectdiscovery/subfinder/v2/pkg/runner"
	"github.com/projectdiscovery/gologger"
)

func main() {
	// 1. Parse command line flags and config files
	options := runner.ParseOptions()

	// 2. Create a new runner instance
	newRunner, err := runner.NewRunner(options)
	if err != nil {
		gologger.Fatal().Msgf("Could not create runner: %s\n", err)
	}

	// 3. Run the enumeration
	err = newRunner.RunEnumeration()
	if err != nil {
		gologger.Fatal().Msgf("Could not run enumeration: %s\n", err)
	}
}