Fierce

1.6.0

A DNS reconnaissance tool for locating non-contiguous IP space.

Verified 24 Sept 2026
pip 1.6.0
GPL-3.0
1.8k stars

Source on GitHub · PyPI release · Markdown

Install and run

otlite install fierce
Installs fierce==1.6.0 into its own virtualenv. otlite lists what it will install and asks before it starts.
otlite run fierce -- d:example.com
fierce receives fierce --domain example.com

No otlite yet? Install it in one line

curl -fsSL https://get.otinstaller.com/otlite | sh

Linux and macOS, no Docker. It uses your Python and pipx when both are there, and otherwise brings its own Python. About otlite · otlite docs

What it takes

Typed inputs after -- become Fierce's own arguments. Anything else after -- passes through unchanged, so every option of the tool still works.

Input	With otlite	`fierce` receives
Domain`d:`	`otlite run fierce -- d:example.com`	`fierce --domain example.com`

What a run leaves

Every run is saved under results/ where you run otlite (or --output, or OTLITE_RESULTS_DIR): what the tool printed, a sidecar with how it ran, and an envelope.

results/fierce/example.com/<time>_fierce_example.com_<run id>.txt
results/fierce/example.com/<time>_fierce_example.com_<run id>.meta.json
results/fierce/example.com/<time>_fierce_example.com_<run id>.envelope.json

{
  "envelope": 1,
  "tool": "fierce@1.6.0",
  "runtime": "otlite",
  "input": { "target": "example.com" },
  "case": null,
  "started_at": "…", "ended_at": "…", "duration_ms": …,
  "exit_code": 0,
  "status": "complete",
  "entities": [{ "type": "url", "value": "…" }, …],
  "warnings": [],
  "output": { "path": "results/fierce/example.com/<time>_fierce_example.com_<run id>.txt", "sha256": "…", "bytes": … }
}

The envelope's shape, the same for every tool; values elided. Its entities are the emails, domains, IP addresses and URLs found in the output, or the tool's own when it prints them.

otlite results --tool fierce

otlite extract fierce

otlite diff fierce example.com

List the saved runs, pull out every indicator, or compare the two latest runs against the same target.

With other tools

These run it with every other installed tool that takes the same input, a few at a time, and save each run:

otlite run --all d:example.com

otlite auto example.com

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