OS Detection

Nerd Cafe | نرد کافه

Purpose

Fingerprint the operating system via TCP/IP behavior.

Command

nmap -O scanme.nmap.org

Output example

Starting Nmap 7.94 ( https://nmap.org ) at 2026-02-19 19:15 Iran Standard Time
Nmap scan report for scanme.nmap.org (94.130.50.12)
Host is up (0.13s latency).
rDNS record for 94.130.50.12: static.12.50.130.94.clients.your-server.de
Not shown: 982 closed tcp ports (reset)
PORT      STATE SERVICE
80/tcp    open  http
443/tcp   open  https
465/tcp   open  smtps
563/tcp   open  snews
636/tcp   open  ldapssl
990/tcp   open  ftps
992/tcp   open  telnets
993/tcp   open  imaps
995/tcp   open  pop3s
1863/tcp  open  msnp
1935/tcp  open  rtmp
2196/tcp  open  unknown
5060/tcp  open  sip
5061/tcp  open  sip-tls
5222/tcp  open  xmpp-client
8443/tcp  open  https-alt
9090/tcp  open  zeus-admin
65000/tcp open  unknown
Device type: general purpose
Running (JUST GUESSING): Linux 4.X|2.6.X|3.X (85%)
OS CPE: cpe:/o:linux:linux_kernel:4.4 cpe:/o:linux:linux_kernel:2.6.39 cpe:/o:linux:linux_kernel:3.10
Aggressive OS guesses: Linux 4.4 (85%), Linux 2.6.39 (85%), Linux 3.10 (85%), Linux 3.10 - 3.16 (85%), Linux 2.6.32 or 3.10 (85%), Linux 4.0 (85%)
No exact OS matches for host (test conditions non-ideal).
Network Distance: 14 hops

OS detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 33.49 seconds

Improve accuracy

nmap -O --osscan-guess scanme.nmap.org

Requirements

• At least one open and one closed port

• Root privileges

💖 Support Our Work

If you find this post helpful and would like to support my work, you can send a donation via TRC-20 (USDT). Your contributions help us keep creating and sharing more valuable content.

TRC-20 Address: TAAVVf9ZxUpbyvTa6Gd5SGPmctBdy4PQwf

Thank you for your generosity! 🙏

Keywords

Nmap, Red Team, Blue Team, Reconnaissance, Port Scanning, Host Discovery, Service Enumeration, OS Fingerprinting, NSE Scripts, SYN Scan, IDS Detection, SIEM Correlation, Network Telemetry, Firewall Evasion, Timing Templates, Attack Surface, Defensive Monitoring, Incident Response, Purple Teaming, MITRE ATT&CK, nerd cafe , نرد کافه

Channel Overview

🌐 Website: www.nerd-cafe.ir

📺 YouTube: @nerd-cafe

🎥 Aparat: nerd_cafe

📌 Pinterest: nerd_cafe

📱 Telegram: @nerd_cafe

📝 Blog: Nerd Café on Virgool

💻 GitHub: nerd-cafe