A useful linux/unix tool, `nmap` scans ips and ports of given hosts:
Nmap 5.21 ( http://nmap.org )
Usage: nmap [Scan Type(s)] [Options] {target specification}
TARGET SPECIFICATION:
Can pass hostnames, IP addresses, networks, etc.
Ex: scanme.nmap.org, 192.168.0.1; 10.0.0-255.1-254
-iL : Input from list of hosts/networks
-iR : Choose random targets
–exclude : Exclude hosts/networks
–excludefile : 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
-PN: Treat all hosts as online — skip host discovery
-PS/PA/PU/PY[portlist]: TCP SYN/ACK, UDP or SCTP discovery to given ports
-PE/PP/PM: ICMP echo, timestamp, and netmask request discovery probes
-PO[protocol list]: IP Protocol Ping
-n/-R: Never do DNS resolution/Always resolve [default: sometimes]
–dns-servers : Specify custom DNS servers
–system-dns: Use OS’s DNS resolver
–traceroute: Trace hop path to each host
SCAN TECHNIQUES:
-sS/sT/sA/sW/sM: TCP SYN/Connect()/ACK/Window/Maimon scans
-sU: UDP Scan
-sN/sF/sX: TCP Null, FIN, and Xmas scans
–scanflags : Customize TCP scan flags
-sI : Idle scan
-sY/sZ: SCTP INIT/COOKIE-ECHO scans
-sO: IP protocol scan
-b : FTP bounce scan
PORT SPECIFICATION AND SCAN ORDER:
-p : Only scan specified ports
Ex: -p22; -p1-65535; -p U:53,111,137,T:21-25,80,139,8080
-F: Fast mode – Scan fewer ports than the default scan
-r: Scan ports consecutively – don’t randomize
–top-ports : Scan most common ports
–port-ratio : Scan ports more common than
SERVICE/VERSION DETECTION:
-sV: Probe open ports to determine service/version info
–version-intensity : Set from 0 (light) to 9 (try all probes)
–version-light: Limit to most likely probes (intensity 2)
–version-all: Try every single probe (intensity 9)
–version-trace: Show detailed version scan activity (for debugging)
SCRIPT SCAN:
-sC: equivalent to –script=default
–script=: is a comma separated list of
directories, script-files or script-categories
–script-args=: provide arguments to scripts
–script-trace: Show all data sent and received
–script-updatedb: Update the script database.
OS DETECTION:
-O: Enable OS detection
–osscan-limit: Limit OS detection to promising targets
–osscan-guess: Guess OS more aggressively
TIMING AND PERFORMANCE:
Options which take
