(root@Mallard:duckwing)# nmap -O -sS 192.168.1.0/24

Starting nmap V. 2.54BETA22 ( www.insecure.org/nmap/ )
Host   (192.168.1.0) seems to be a subnet broadcast address (returned 2 extra pings). Skipping host.
Insufficient responses for TCP sequencing (3), OS detection may be less accurate
Insufficient responses for TCP sequencing (3), OS detection may be less accurate
Insufficient responses for TCP sequencing (3), OS detection may be less accurate
Interesting ports on Mallard (192.168.1.25):
(The 1533 ports scanned but not shown below are in state: closed)
Port       State       Service
9/tcp      open        discard           
13/tcp     open        daytime                 
22/tcp     open        ssh
25/tcp     open        smtp
37/tcp     open        time
111/tcp    open        sunrpc
113/tcp    open        auth
139/tcp    open        netbios-ssn
631/tcp    open        cups                    

No exact OS matches for host (If you know what OS is running on it, see http://w
ww.insecure.org/cgi-bin/nmap-submit.cgi).
TCP/IP fingerprint:
SInfo(V=2.54BETA22%P=i586-pc-linux-gnu%D=5/30%Time=3B15D633%O=9%C=1)
T1(Resp=Y%DF=Y%W=7FFF%ACK=S++%Flags=AS%Ops=MNNTNW)
T2(Resp=N)
T3(Resp=Y%DF=Y%W=7FFF%ACK=S++%Flags=AS%Ops=MNNTNW)
T4(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
T5(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
T6(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
T7(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
PU(Resp=Y%DF=Y%TOS=C0%IPLEN=164%RIPTL=148%RID=E%RIPCK=E%UCK=E%ULEN=134%DAT=E)



Uptime 17.255 days (since Sun May 13 16:20:10 2001)

Warning:  OS detection will be MUCH less reliable because we did not find at least
 1 open and 1 closed TCP port
All 1542 scanned ports on  (192.168.1.33) are: closed
Too many fingerprints match this host for me to give an accurate OS guess
Interesting ports on  (192.168.1.254):
(The 1537 ports scanned but not shown below are in state: closed)
Port       State       Service
9/tcp      open        discard                 
13/tcp     open        daytime                 
23/tcp     open        telnet                  
37/tcp     open        time                    
113/tcp    open        auth                    

Remote operating system guess: Linux 2.1.122 - 2.2.16
Uptime 49.211 days (since Wed Apr 11 17:24:45 2001)
Host   (192.168.1.255) seems to be a subnet broadcast address (returned 2 extra pi
ngs). Skipping host.

Nmap run completed -- 256 IP addresses (3 hosts up) scanned in 113 seconds