Nmap

Nmap is a tool for scaning and monitoring host. Nmap is stand for Network Mapper. Main utilities of Nmap is to audit for each host. This tool is developed from time to time. The usefulness of Nmap that favorite is OS Fingerprinting ( To verify what os of the destination host are running ) Nmap can mapping network to determine what hosts are available. This tool is popular in hackker world including administrator because it's very profitably and creditably for securities scanning

Example of nmap command

It's useful for sweep ping of your network
#nmap -sP 192.168.1.*

Ping over tcp connection
#nmap -PT[port_number] host
ex
#nmap -PT6000 192.168.1.1

TCP-Connect
#nmap -sT 192.168.1.1

TCP SYN
#nmap -sS 192.168.1.1

Source Port
#nmap -sS 192.168.1.1

FIN Scan
#nmap -sF 192.168.1.1

Reverse Ident Scans
#nmap -I -sS -p 80 192.168.1.1

XMAS Scan
#nmap -sX 192.168.1.1

How to NULL SCAN
#nmap -sN 192.168.1.1

How to RPC Scan
#nmap -sR 192.168.1.1

IP Protocol Scan
#nmap -sO 192.168.1.1

How to ACK Scan
#nmap -sA target_address

How to UDP Port Scan
#nmap -sU 192.168.1.1

Check OS (Operating System)
#nmap -o 192.168.1.1