1) Get info about remote host ports and OS detection
nmap -sS -P0 -sV -O <target>
Where < target > may be a single IP, a hostname or a subnet
-sS TCP SYN scanning (also known as half-open, or stealth scanning)
-P0 option allows you to switch off ICMP pings.
-sV option enables version detection
-O flag attempt to identify the remote operating system Other option:
-A option enables both OS fingerprinting and version detection
-v use -v twice for more verbosity.
nmap -sS -P0 -A -v < target >
2) Get list of servers with a specific port open
nmap -sT -p 80 -oG – 192.168.1.* | grep open
Change the -p argument for the port number. See “man nmap” for different ways to specify address ranges.
3) Find all active IP addresses in a network
nmap -sP 192.168.0.*
There are several other options. This one is plain and simple.
Another option is:
nmap -sP 192.168.0.0/24
for specific subnets
4) Ping a range of IP addresses
nmap -sP 192.168.1.100-254
nmap accepts a wide variety of addressing notation, multiple targets/ranges, etc.
5) Find unused IPs on a given subnet
nmap -T4 -sP 192.168.2.0/24 && egrep “00:00:00:00:00:00″ /proc/net/arp
nmap -PN -T4 -p139,445 -n -v –script=smb-check-vulns –script-args safe=1 192.168.0.1-254
replace 192.168.0.1-256 with the IP’s you want to check.
7) Scan Network for Rogue APs.
nmap -A -p1-85,113,443,8080-8100 -T4 –min-hostgroup 50 –max-rtt-timeout 2000 –initial-rtt-timeout 300 –max-retries 3 –host-timeout 20m –max-scan-delay 1000 -oA wapscan 10.0.0.0/8
I’ve used this scan to successfully find many rogue APs on a very, very large network.
8) Use a decoy while scanning ports to avoid getting caught by the sys admin
sudo nmap -sS 192.168.0.10 -D 192.168.0.2
Scan for open ports on the target device/computer (192.168.0.10) while setting up a decoy address (192.168.0.2). This will show the decoy ip address instead of your ip in targets security logs. Decoy address needs to be alive. Check the targets security log at /var/log/secure to make sure it worked.
9) List of reverse DNS records for a subnet
nmap -R -sL 209.85.229.99/27 | awk ‘{if($3==”not”)print”(“$2″) no PTR”;else print$3″ is “$2}’ | grep ‘(‘This command uses nmap to perform reverse DNS lookups on a subnet. It produces a list of IP addresses with the corresponding PTR record for a given subnet. You can enter the subnet in CDIR notation (i.e. /24 for a Class C)). You could add “–dns-servers x.x.x.x” after the “-sL” if you need the lookups to be performed on a specific DNS server. On some installations nmap needs sudo I believe. Also I hope awk is standard on most distros.
10) How Many Linux And Windows Devices Are On Your Network?
sudo nmap -F -O 192.168.0.1-255 | grep “Running: ” > /tmp/os; echo “$(cat /tmp/os | grep Linux | wc -l) Linux device(s)”; echo “$(cat /tmp/os | grep Windows | wc -l) Window(s) devices”
Hope you have fun, and remember don’t practice these techniques on machines or networks that are not yours.
ref :
http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&gfns=1&q=nmap+scan+os+grep
