$ sudo nmap -v -O -sS 69.169.91.15

Starting Nmap 5.00 ( http://nmap.org ) at 2012-06-06 17:00 EDT
NSE: Loaded 0 scripts for scanning.
Initiating Ping Scan at 17:00
Scanning 69.169.91.15 [4 ports]
Completed Ping Scan at 17:00, 0.32s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 17:00
Completed Parallel DNS resolution of 1 host. at 17:00, 0.60s elapsed
Initiating SYN Stealth Scan at 17:00
Scanning 69.169.91.15 [1000 ports]
Discovered open port 80/tcp on 69.169.91.15
Completed SYN Stealth Scan at 17:00, 6.17s elapsed (1000 total ports)
Initiating OS detection (try #1) against 69.169.91.15
Retrying OS detection (try #2) against 69.169.91.15
Host 69.169.91.15 is up (0.028s latency).
Interesting ports on 69.169.91.15:
Not shown: 994 closed ports
PORT     STATE    SERVICE
25/tcp   filtered smtp
80/tcp   open     http
135/tcp  filtered msrpc
139/tcp  filtered netbios-ssn
445/tcp  filtered microsoft-ds
4444/tcp filtered krb524
Device type: general purpose|specialized|WAP|broadband router
Running (JUST GUESSING) : Linux 2.6.X|2.4.X (92%), Infoblox NIOS 4.X (85%)
Aggressive OS guesses: Linux 2.6.18 (CentOS 5.1, x86) (92%), Infoblox NIOS Release 4.1r2-5-22263 (85%), DD-WRT v23 (Linux 2.4.34) (85%), OpenWrt Kamikaze 8.09 (Linux 2.6.25.20) (85%), Linux 2.6.23 (85%), Linux 2.6.9 (85%), Linux 2.6.9 - 2.6.24 (85%)
No exact OS matches for host (test conditions non-ideal).
Uptime guess: 4.211 days (since Sat Jun  2 11:57:06 2012)
Network Distance: 11 hops
TCP Sequence Prediction: Difficulty=260 (Good luck!)
IP ID Sequence Generation: All zeros

Read data files from: /usr/share/nmap
OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 11.53 seconds
           Raw packets sent: 1141 (52.088KB) | Rcvd: 1022 (42.344KB)