Nmap (“Network Mapper”) is a free and open source (license) utility for network discovery and security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. It was designed to rapidly scan large networks, but works fine against single hosts. Nmap runs on all major computer operating systems, and official binary packages are available for Linux, Windows, and Mac OS X. In addition to the classic command-line Nmap executable, the Nmap suite includes an advanced GUI and results viewer (Zenmap), a flexible data transfer, redirection, and debugging tool (Ncat), a utility for comparing scan results (Ndiff), and a packet generation and response analysis tool (Nping).
Standard scan with OS/Version discovery using SYN messages (option -n implies DNS resolution)
nmap -A -sS [host] nmap -A -sS -n [host]
Scan without usual active hosts discovery
nmap -A -PN [host]
Scan of all opened UDP ports on host
nmap -A -sU [host]
Specify ports you want to scan (UDP and/or TCP)
nmap -pU:53,137,T:21-25,80,8080 [host]
Check if an host is existing on network
nmap -sP [host]
Scan an entire IP range
nmap -A 192.168.0-255
Usurp source IP address. Here, we are scanning [host] through eth1 interface using ip 192.168.0.1 from port 443
nmap -S 192.168.0.1 -g 443 -e eth1 -P0 [host]
Usurp MAC address
nmap --spoof-mac 00:01:02:03:04:05 [host] nmap --spoof-mac Cisco [host]
Trace packets and data you just sent/received (can be used when you are using usurpation)
nmap --packet-trace -S192.168.0.1 -eth1 [host]
Choose an output file for getting results
nmap -oN results [host] nmap -oX results.xml [host]
For each of previous commands, you can use:
- -v to get a verbose mode
- -T[0-5] to define an “aggressivity” profile for the scan (usually, T4 is used)
More information on official website : http://www.nmap.org