# Fierce (otlite)

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

- Takes: Domain, IP address
- Install: `otlite install fierce`, into its own virtualenv
- Pinned: [fierce==1.6.0](https://pypi.org/project/fierce/1.6.0/)
- Command: `fierce`
- Python: any otlite runs on (3.10 or newer)
- Verified: 24 Sept 2026, version 1.6.0 on Ubuntu 26.04 LTS, Python 3.12.14
- Licence: GPL-3.0; 1,812 GitHub stars
- Source: https://github.com/mschwager/fierce

otlite is the no-Docker edition of OTInstaller for Linux and macOS: [install it](https://otinstaller.com/otlite) with `curl -fsSL https://get.otinstaller.com/otlite | sh`.

## Run it

| Input | otlite command | Fierce receives |
| --- | --- | --- |
| Domain | `otlite run fierce -- d:example.com` | `fierce --domain example.com` |

Arguments after `--` that aren't typed inputs go to the tool unchanged.

## What a run leaves

- `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`

The envelope is the same shape for every tool: the tool and version, the input, timing, exit code and status, the emails, domains, IP addresses and URLs found in the output, and the output file's path, hash and size. `otlite results --tool fierce` lists saved runs, `otlite extract fierce` pulls out indicators and `otlite diff fierce example.com` compares the two latest runs.

## With other tools

`otlite run --all d:example.com` and `otlite auto example.com` run it with every other installed tool that takes the same input.

## Related tools

- [Spiderfoot](https://otinstaller.com/otlite/tools/spiderfoot.md): SpiderFoot automates OSINT for threat intelligence and mapping your attack surface
- [Bbot](https://otinstaller.com/otlite/tools/bbot.md): The recursive internet scanner for hackers
- [Dnstwist](https://otinstaller.com/otlite/tools/dnstwist.md): Domain name permutation engine for detecting homograph phishing attacks, typo squatting, and brand impersonation
- [Ivre](https://otinstaller.com/otlite/tools/ivre.md): Network recon framework
- [Finalrecon](https://otinstaller.com/otlite/tools/finalrecon.md): All In One Web Recon
- [Secator](https://otinstaller.com/otlite/tools/secator.md): secator - the pentester's swiss knife

[All 47 otlite tools](https://otinstaller.com/otlite/tools) · [otlite docs](https://otinstaller.com/docs/otlite.md)