Unicornscan — Asynchronous Scanner for Security Research
What it is
Unicornscan is a network reconnaissance tool built with a focus on speed and detail. Unlike traditional port scanners, it uses an asynchronous stateless design that allows it to send and analyze a massive number of packets very quickly. It’s popular among penetration testers and researchers who need visibility into large address ranges without waiting for hours.
How it actually works
At the core, Unicornscan separates packet generation and response handling. It doesn’t wait for each probe to finish before sending the next — instead, it floods the target range with crafted packets and collects responses asynchronously. This lets it uncover open ports, running services, and even some quirks of TCP/IP stacks much faster than classic tools.
The scanner can also log raw packet data, making it useful for research or feeding results into other tools. Admins often pair it with Nmap: Unicornscan for fast discovery, Nmap for deep service fingerprinting.
Main uses
– Fast port discovery across wide IP ranges.
– Baseline network mapping before a penetration test.
– Research into TCP/IP behavior, OS fingerprinting quirks, and protocol edge cases.
– Feeding other tools like Nmap or custom analyzers with pre-scanned data.
Installation quick notes
On Debian/Ubuntu:
sudo apt update && sudo apt install unicornscan -y
On CentOS/RHEL:
sudo yum install epel-release -y
sudo yum install unicornscan -y
Basic scan example (all TCP ports on a host):
sudo unicornscan -Iv -p1-65535 target.example.com
Strengths and caveats
Unicornscan’s asynchronous engine is its biggest strength — it can probe huge ranges in a fraction of the time. It also provides raw access to responses, which is handy for custom analysis.
On the downside, it’s not actively maintained, so documentation is dated and newer OS quirks may not be handled perfectly. Output formatting isn’t as polished as Nmap, and it’s best used as part of a toolkit rather than a standalone solution.
Comparison
| Tool | Edge | Best fit |
| Unicornscan | Very fast, async scanning, raw packet access | Researchers, large-scale scans |
| Nmap | Deep service detection, scripts, fingerprints | Detailed probing after discovery |
| Masscan | Insanely fast, internet-wide scans | Wide internet sweeps, huge ranges |
| ZMap | Specialized fast single-protocol scans | Academic research, large census scans |