Nmap : Explanation and uses with example

Nmap tutorial

Nmap hacker tool explanation usages with example

NAMP :- NMAP(network mapper) is a free and open source 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 is an important and powerful tool for hacking. It can be used in GUI mode and command line both.

Usages

Nmap is mainly use for network discovery and security auditing.

It is used for Vulnerability detection, penetration testing, host discovery, OS detection (you can know exist host in your network and which services they are using), port scanning(which port is open on your server or host like TCP,UDP).

Nmap uses row IP packet in novel ways to determine what host are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS version) they are running.

Most operating systems are supported Nmap including Linux, Microsoft Windows, FreeBSD, OpenBSD, Solaris, IRIX, Mac, NetBSD, Sun OS, Amiga and more.

Example of Nmap :-

First of all you have to install Nmap in your system. If you are using Kali Linux then it’s preinstalled in Kali Linux. If you don’t able to use Nmap in Kali Linux then you can also install it using terminal in Kali. So open terminal and run command sudo apt-get install nmap. To check Nmap is installed in your system or not, type in terminal nmap. It will open help of Nmap tool.

root@MikeyToTec:~#nmap

Nmap 5.61TEST5 ( 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 : 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

  -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 : 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,S:9

  -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-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=: Show help about scripts.

            is a comma separted 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  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 : Parallel host scan group sizes

  --min-parallelism/max-parallelism : Probe parallelization

  --min-rtt-timeout/max-rtt-timeout/initial-rtt-timeout : Specifies

      probe round trip time.

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

  --host-timeout : Give up on target after this long

  --scan-delay/--max-scan-delay : Adjust delay between probes

  --min-rate : Send packets no slower than  per second

  --max-rate : Send packets no faster than  per second

FIREWALL/IDS EVASION AND SPOOFING:

  -f; --mtu : fragment packets (optionally w/given MTU)

  -D : Cloak a scan with decoys

  -S : Spoof source address

  -e : Use specified interface

  -g/--source-port : Use given port number

  --data-length : Append random data to sent packets

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

  --ttl : Set IP time-to-live field

  --spoof-mac : Spoof your MAC address

  --badsum: Send packets with a bogus TCP/UDP/SCTP checksum

OUTPUT:

  -oN/-oX/-oS/-oG : Output scan in normal, XML, s|: 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)

  --log-errors: Log errors/warnings to the normal-format output file

  --append-output: Append to rather than clobber specified output files

  --resume : Resume an aborted scan

  --stylesheet : 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 : 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

Some example for usage of Nmap are given below :-

Ping scan :- For ping scan run command nmap -sP [ip range] (example nmap -sP 192.168.1.0/24). Ping scan scans the network, listing machines that respond to ping. It will check exist host in this network. It displays IP addresses, MAC addresses and name of exists hosts in the network.

OS detection :- You can scan and detect OS in your network using Nmap. You can also know the version of detected OS. For OS detection run command in terminal nmap -sS -A [host ip] (example nmap -sS -A 192.168.1.14), here -sS is used for port scan and -A is used for OS detection. This command will display information of the given IP host like open port, OS version, MAC address.

If you want to scan website for check open ports, IP address etc. then run command nmap url (example nmap nmap.org).