Pour connaitre le système d'exploitation d'un serveur distant, vous pouvez utilisez NMAP ! avec l'option -O.

Mais si vous êtes allergiques aux programmes en ligne de commande, vous pouvez utiliser la version GUI : Zenmap (version GUI de nmap)

Allez sur nmap.org pour télécharger Nmap.

Ensuite ouvrez l'invite de commande, pour cela Aller dans le menu démarrer >> Exécuter >> taper CMD (cf. Invite de commande)

Vous n'avez plus qu'à exécuter ces commandes !

Microsoft Windows [version 6.0.6002]
Copyright (c) 2006 Microsoft Corporation. Tous droits réservés.

C:\Users\clintm>cd C:\Program Files\Nmap

C:\Program Files\Nmap>nmap -O -v scanme.nmap.org

Starting Nmap 5.21 ( http://nmap.org ) at 2010-03-21 01:09 Paris, Madrid
Initiating Ping Scan at 01:09
Scanning scanme.nmap.org (64.13.134.52) [4 ports]
Completed Ping Scan at 01:09, 0.56s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 01:09
Completed Parallel DNS resolution of 1 host. at 01:09, 0.00s elapsed
Initiating SYN Stealth Scan at 01:09
Scanning scanme.nmap.org (64.13.134.52) [1000 ports]
Discovered open port 80/tcp on 64.13.134.52
Discovered open port 53/tcp on 64.13.134.52
Completed SYN Stealth Scan at 01:09, 20.48s elapsed (1000 total ports)
Initiating OS detection (try #1) against scanme.nmap.org (64.13.134.52)
Nmap scan report for scanme.nmap.org (64.13.134.52)
Host is up (0.21s latency).
Not shown: 994 filtered ports
PORT      STATE  SERVICE
25/tcp    closed smtp
53/tcp    open   domain
70/tcp    closed gopher
80/tcp    open   http
113/tcp   closed auth
31337/tcp closed Elite
Device type: general purpose
Running: Linux 2.6.X
OS details: Linux 2.6.13 - 2.6.28
Uptime guess: 24.485 days (since Wed Feb 24 13:30:56 2010)
TCP Sequence Prediction: Difficulty=196 (Good luck!)
IP ID Sequence Generation: All zeros

Read data files from: C:\Users\*****\AppData\Local\Temp\nmap-5.21-win32\nmap-5.21
OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .

Nmap done: 1 IP address (1 host up) scanned in 24.40 seconds
           Raw packets sent: 3026 (134.690KB) | Rcvd: 38 (1984B)

C:\Program Files\Nmap>