Basic Nmap on Linux

Nmap stands for Network Mapper. It  is a free and open source utility for network discovery and security auditing. More details click here

To install the Nmap,

manivel@manivel ~ $ sudo apt-get install nmap

After installation of nmap, simply type the nmap command on the terminal and you will get help page.

manivel ~ #  nmap 

Nmap 7.01 ( https://nmap.org )

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

  -sn: Ping Scan - disable port scan

  -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 <serv1[,serv2],...>: 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 <flags>: Customize TCP scan flags

  -sI <zombie host[:probeport]>: Idle scan

  -sY/sZ: SCTP INIT/COOKIE-ECHO scans

  -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,S:9

  --exclude-ports <port ranges>: Exclude the specified ports from scanning

  -F: Fast mode - Scan fewer ports than the default scan

  -r: Scan ports consecutively - don't randomize

  --top-ports <number>: Scan <number> most common ports

  --port-ratio <ratio>: Scan ports more common than <ratio>

SERVICE/VERSION DETECTION:

  -sV: Probe open ports to determine service/version info

  --version-intensity <level>: 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=<Lua scripts>: <Lua scripts> is a comma separated list of

           directories, script-files or script-categories

  --script-args=<n1=v1,[n2=v2,...]>: provide arguments to scripts

  --script-args-file=filename: provide NSE script args in a file

  --script-trace: Show all data sent and received

  --script-updatedb: Update the script database.

  --script-help=<Lua scripts>: Show help about scripts.

           <Lua scripts> is a comma-separated list of script-files or

           script-categories.

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 <time> are in seconds, or append 'ms' (milliseconds),

  's' (seconds), 'm' (minutes), or 'h' (hours) to the value (e.g. 30m).

  -T<0-5>: Set timing template (higher is faster)

  --min-hostgroup/max-hostgroup <size>: Parallel host scan group sizes

  --min-parallelism/max-parallelism <numprobes>: Probe parallelization

  --min-rtt-timeout/max-rtt-timeout/initial-rtt-timeout <time>: Specifies

      probe round trip time.

  --max-retries <tries>: Caps number of port scan probe retransmissions.

  --host-timeout <time>: Give up on target after this long

  --scan-delay/--max-scan-delay <time>: Adjust delay between probes

  --min-rate <number>: Send packets no slower than <number> per second

  --max-rate <number>: Send packets no faster than <number> per second

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

  --proxies <url1,[url2],...>: Relay connections through HTTP/SOCKS4 proxies

  --data <hex string>: Append a custom payload to sent packets

  --data-string <string>: Append a custom ASCII string to sent packets

  --data-length <num>: Append random data to sent packets

  --ip-options <options>: Send packets with specified ip options

  --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/SCTP 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 -vv or more for greater effect)

  -d: Increase debugging level (use -dd or more for greater effect)

  --reason: Display the reason a port is in a particular state

  --open: Only show open (or possibly open) ports

  --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 Nmap.Org for more portable XML

  --no-stylesheet: Prevent associating of XSL stylesheet w/XML output

MISC:

  -6: Enable IPv6 scanning

  -A: Enable OS detection, version detection, script scanning, and traceroute

  --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

  --unprivileged: Assume the user lacks raw socket privileges

  -V: Print version number

  -h: Print this help summary page.

EXAMPLES:

  nmap -v -A scanme.nmap.org

  nmap -v -sn 192.168.0.0/16 10.0.0.0/8

  nmap -v -iR 10000 -Pn -p 80

SEE THE MAN PAGE (https://nmap.org/book/man.html) FOR MORE OPTIONS AND EXAMPLES

manivel ~ #

If you get the above screen, it means you have installed the nmap successfully.