root@thehacksparrow:~/writeups$ SYSTEM ONLINE
root@sparrow:~/writeups$ cat sublist3r.md
// recon

Sublist3r

22 Jul 2026 · 2 min read

Sublist3r is a passive OSINT tool for enumerating subdomains using multiple search engines and external services. Fast, lightweight, and heavily used in the initial recon phase.

TypeCLI (Python)
PlatformKali / Linux
Sublist3r cheat sheet

Basic commands

CommandWhat it does
sublist3r -d domain.comEnumerate the domain's subdomains
sublist3r -d domain.com -o subdomains.txtSave results to a file
sublist3r -d domain.com -t 50Speed up with more threads

Advanced commands

CommandWhat it does
sublist3r -d domain.com -b -w /usr/share/wordlists/dnsmap.txtActive subdomain brute force
sublist3r -d domain.com -e google,yahoo,bingUse specific search engines
sublist3r -d domain.com -o output.txt -nSilent mode (results only)

Pros and limitations

ProsLimitations
Very fast and lightweightDoesn't find internal subdomains
Passive OSINT (no noise generated)Depends on public info, may return stale entries
Many compatible sourcesDoesn't detect services or ports

Notes: combine it with Amass and Subfinder for maximum coverage. After getting subdomains, run Nmap against them; to know which are alive, pair it with httprobe/httpx.

Responsible use

These commands are for systems you own or have explicit written authorisation to test (labs, CTFs, contracted engagements). Using them against third-party infrastructure without permission is illegal in most countries.