nmap command magic linux

nmap : Network exploration tool and security / port scanner
   Display open port number and protocol, service name, and state
  
   Syantax:
   nmap options hostnames/IPaddresses/networks
   -A, to enable OS and version detection(A detailed scan)
   -T4 for faster execuation of cmd
   -iL InputFileName contain list of IPS/hostname etc..
   --excludefile ExcludeFileName
   -sL: List Scan
   -sP: Ping Scan
   -pPortNo  EG: -P22 etc...
   -e eth0 : scan particulat interface
   --packet-trace  IP/Hostname : Show all packets sent and received
   --iflist : list all active links info MAc add etc..
  
If system ports have been changed for a particular application service
and is open then you can trace it
EG:
server1.example.com : vi /etc/ssh/sshd_conf
#Port 22  --> Port 1022 (For ssh changed to 22 to 1022 )

Now scan from system1.example.com:
# nmap -v -A server1.example.com  (An detailed OS scan)

1022/tcp open  ssh         OpenSSH 4.3 (protocol 2.0)
  
OR:
#nmap -T4 -sV server1.example.com (An detailed open port scan)

Examples:  
# nmap -T4 -p22 192.168.8.10          :Scan for port 22
# nmap 192.168.8.10 |grep -i tcp      :Opend TCP ports

# nmap -sP 192.168.8.*                :Which hosts in my subnet
eg. output:
Host ntp.example.com (192.168.8.7) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host ns1.example.com (192.168.8.8) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host mail.example.com (192.168.8.9) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host server.example.com (192.168.8.10) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host client.example.com (192.168.8.20) appears to be up.
Nmap finished: 256 IP addresses (5 hosts up) scanned in 9.375 seconds


# Faced any problem Feedback in above contact me
#===============================Scratch===============================#
# AND Many More .....................Linux is Endless                 #
#========================== Hope you Liked IT ========================#
#                                       nmap cmd -- BY Shirish Shukla #
#                                                   RHC Engineer 2010 #
#                                             shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
# "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#=====================================================================#
# TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk     #
#=====================================================================#