Nmap Cheatsheet

Written by Alireza Liaghat || Reviewed by Dale Hobbs

This blog is part of Offensive Tooling Cheatsheets: An Infosec Survival Guide Resource. You can learn more and find all of the cheatsheets HERE: https://www.blackhillsinfosec.com/offensive-tooling-cheatsheets/

Nmap Cheatsheet: PRINT-FRIENDLY PDF

Find the tool here: https://nmap.org/

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Nmap is a powerful open-source tool commonly used by system/network administrators and security professionals to perform network discovery, security auditing, and basic vulnerability assessment. Nmap allows you to quickly identify live hosts, open ports, running services, operating systems, and potential security risks within a network. This cheatsheet provides a reference to essential Nmap commands, scanning techniques, and common use cases to help streamline your network reconnaissance and troubleshooting tasks.

The Nmap Formula

Nmap + Target + Type + Port + Detection + Timing + Scripts + Evasion

TARGET

What do you want to scan?

Example	Description	Use Case
192.168.x.x	Scan the specified IP address	Used when there is only one target IP address.
domain.com	Scan the specified domain	Used when there is only one target domain.
-iL target.txt	Scan from a list of host addresses	Used when searching a known range of hosts.
--unique	Scans each address only once	Used in combination with lists. Avoids duplicate scans to speed up the scan.
-n	No DNS resolution	Speeds up scanning by skipping reverse DNS resolution.

TYPE

How do you want to scan?

Example	Description	Use Case
-sT	Full TCP 3-Way Handshake Scan	Most reliable scan. Use when not worried about firewalls.
-sS	“Stealth” scan. Impartial 3-Way Handshake	Does not establish a full handshake. “Dumb” firewalls will only see this as regular poor connection.
-sU	Scan using UDP	Preferred for scanning DNS (53), SNMP (161), DHCP (67), TFTP (69), etc.

PORT

What port do you want to scan?

Example	Description	Use Case
-p 80,443	Scans only the comma-separated ports	Useful for when scanning a host for a specific attack surface.
-p 1-65535	Scans all possible ports	Useful for all ports in use, including ephemeral (temporary) ports.

DETECTION

What do you want to detect?

Example	Description	Use Case
-sV	Probe for service/version	Useful for when mapping and identifying a network
--version-light	Try the most likely probes for detection	Useful for when mapping and identifying a network.
--version-all	Try every available probe (max intensity)	Useful for when mapping and identifying a network..
-O	OS Detection	Useful for when mapping and identifying a network.

TIMING

How fast do you want to scan?

Example	Description	Use Case
--max-rate 5	Sends a maximum of 5 probes per second	Limits network traffic to avoid disruptions to the network.
--scan-delay 1	Adds 1 second delay between probes	Limits network traffic to avoid disruptions to the network.
--host-timeout 1	Give up on a particular port after 1 second	Limits network traffic and useful for slow responding devices.

SCRIPTS

What additional scripts do you want?

Example	Description	Use Case
--script=whois	Spoofs the source IP address	Used when mapping a network.
--scripts=smb-enum-shares	Adds random data to packets	Identifies SMB shares that might be exposed.
--script=vulners	Uses a proxy to scan	Identifies known/unpatched vulnerabilities in a network.

EVASION

How sneaky do you want to be?

Example	Description	Use Case
-spoof-mac 00:0C:29:6F:F3:6B	Spoofs the source MAC address	Useful for when the network switch restricts connectivity using MAC addresses
S 192.168.1.1	Spoofs the source IP address	Useful for when the network switch restricts connectivity using IP addresses
--data-length 5	Adds random data to packets	Useful for when trying to camouflage the network traffic caused by the scan
--proxies 192.168.5.5	Uses a proxy to scan	Useful for when navigating a scan through an IP-based filter

Example formula of a slow and thorough search:

nmap 192.168.10.50 -sT -p1-65535 -version-light -max-rate 5 --script=vulners -S 192.168.1.1 

Common Port States

open:	An application is actively accepting TCP connections or UDP datagrams on this port.
closed:	The port is accessible. Nmap probes received a response but was indicated that there is no application listening.
filtered:	Nmap cannot determine if the port is open. This could be caused by firewalls dropping packets or by network congestion.

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