Nmap 3.96BETA3 ( http://www.insecure.org/nmap/ )
Usage: nmap [Scan Type(s)] [Options] {target specification}
TARGET SPECIFICATION:
  Can pass hostnames, IP addresses, networks, etc.
  Ex: scanme.nmap.org, microsoft.com/24, 192.168.0.1; 10.0.0-255.1-254
  -iL <inputfilename>: Input from list of hosts/networks
  -iR <num hosts>: Choose random targets
  --exclude <host1[,host2][,host3],...>: Exclude hosts/networks
  --excludefile <exclude_file>: Exclude list from file
HOST DISCOVERY:
  -sL: List Scan - simply list targets to scan
  -sP: Ping Scan - go no further than determining if host is online
  -P0: Treat all hosts as online -- skip host discovery
  -PS/PA/PU [portlist]: TCP SYN/ACK or UDP discovery to given ports
  -PE/PP/PM: ICMP echo, timestamp, and netmask request discovery probes
  -n/-R: Never do DNS resolution/Always resolve [default: sometimes]
  --dns_servers <serv1[,serv2],...>: Specify custom DNS servers
  --system_dns: Use OS's DNS resolver
SCAN TECHNIQUES:
  -sS/sT/sA/sW/sM: TCP SYN/Connect()/ACK/Window/Maimon scans
  -sN/sF/sX: TCP Null, FIN, and Xmas scans
  --scanflags <flags>: Customize TCP scan flags
  -sI <zombie host[:probeport]>: Idlescan
  -sO: IP protocol scan
  -b <ftp relay host>: FTP bounce scan
PORT SPECIFICATION AND SCAN ORDER:
  -p <port ranges>: Only scan specified ports
    Ex: -p22; -p1-65535; -p U:53,111,137,T:21-25,80,139,8080
  -F: Fast - Scan only the ports listed in the nmap-services file)
  -r: Scan ports consecutively - don't randomize
SERVICE/VERSION DETECTION:
  -sV: Probe open ports to determine service/version info
  --version_light: Limit to most likely probes for faster identification
  --version_all: Try every single probe for version detection
  --version_trace: Show detailed version scan activity (for debugging)
OS DETECTION:
  -O: Enable OS detection
  --osscan_limit: Limit OS detection to promising targets
  --osscan_guess: Guess OS more aggressively
TIMING AND PERFORMANCE:
  -T[0-5]: Set timing template (higher is faster)
  --min_hostgroup/max_hostgroup <size>: Parallel host scan group sizes
  --min_parallelism/max_parallelism <msec>: Probe parallelization
  --min_rtt_timeout/max_rtt_timeout/initial_rtt_timeout <msec>: Specifies
      probe round trip time.
  --max_retries <tries>: Caps number of port scan probe retransmissions.
  --host_timeout <msec>: Give up on target after this long
  --scan_delay/--max_scan_delay <msec>: Adjust delay between probes
FIREWALL/IDS EVASION AND SPOOFING:
  -f; --mtu <val>: fragment packets (optionally w/given MTU)
  -D <decoy1,decoy2[,ME],...>: Cloak a scan with decoys
  -S <IP_Address>: Spoof source address
  -e <iface>: Use specified interface
  -g/--source_port <portnum>: Use given port number
  --data_length <num>: Append random data to sent packets
  --ttl <val>: Set IP time-to-live field
  --spoof_mac <mac address/prefix/vendor name>: Spoof your MAC address
  --badsum: Send packets with a bogus TCP/UDP checksum
OUTPUT:
  -oN/-oX/-oS/-oG <file>: Output scan in normal, XML, s|<rIpt kIddi3,
     and Grepable format, respectively, to the given filename.
  -oA <basename>: Output in the three major formats at once
  -v: Increase verbosity level (use twice for more effect)
  -d[level]: Set or increase debugging level (Up to 9 is meaningful)
  --packet_trace: Show all packets sent and received
  --iflist: Print host interfaces and routes (for debugging)
  --append_output: Append to rather than clobber specified output files
  --resume <filename>: Resume an aborted scan
  --stylesheet <path/URL>: XSL stylesheet to transform XML output to HTML
  --webxml: Reference stylesheet from Insecure.Org for more portable XML
  --no_stylesheet: Prevent associating of XSL stylesheet w/XML output
MISC:
  -6: Enable IPv6 scanning
  -A: Enables OS detection and Version detection
  --datadir <dirname>: Specify custom Nmap data file location
  --send_eth/--send_ip: Send using raw ethernet frames or IP packets
  --privileged: Assume that the user is fully privileged
  -V: Print version number
  -h: Print this help summary page.
EXAMPLES:
  nmap -v -A scanme.nmap.org
  nmap -v -sP 192.168.0.0/16 10.0.0.0/8
  nmap -v -iR 10000 -P0 -p 80
SEE THE MAN PAGE FOR MANY MORE OPTIONS, DESCRIPTIONS, AND EXAMPLES