Nmap Cheat Sheet

Reference guide for scanning networks with Nmap.

Table of Contents

  1. What is Nmap?
  2. How to Use Nmap
    1. Command Line
  3. Basic Scanning Techniques
    1. Scan a Single Target
    2. Scan Multiple Targets
    3. Scan a List of Targets
    4. Scan a Range of Hosts
    5. Scan an Entire Subnet
    6. Scan Random Hosts
    7. Exclude Targets From a Scan
    8. Exclude Targets Using a List
    9. Perform an Aggresive Scan
    10. Scan an IPv6 Target
  4. Port Scanning Options
    1. Perform a Fast Scan
    2. Scan Specific Ports
    3. Scan Ports by Name
    4. Scan Ports by Protocol
    5. Scan All Ports
    6. Scan Top Ports
    7. Perform a Sequential Port Scan
    8. Attempt to Guess an Unknown OS
    9. Service Version Detection
    10. Troubleshoot Version Scan
    11. Perform a RPC Scan
  5. Discovery Options
    1. Perform a Ping Only Scan
    2. Do Not Ping
    3. TCP SYN Ping
    4. TCP ACK Ping
    5. UDP Ping
    6. SCTP INIT Ping
    7. ICMP Echo Ping
    8. ICMP Timestamp Ping
    9. ICMP Address Mask Ping
    10. IP Protocol Ping
    11. ARP Ping
    12. Traceroute
    13. Force Reverse DNS Resolution
    14. Disable Reverse DNS Resolution
    15. Alternative DNS Lookup
    16. Manually Specify DNS Server
    17. Create a Host List
  6. Firewall Evasion Techniques
    1. Fragment Packets
    2. Specify a Specific MTU
    3. Use a Decoy
    4. Idle Zombie Scan
    5. Manually Specify a Source Port
    6. Append Random Data
    7. Randomize Target Scan Order
    8. Spoof MAC Address
    9. Send Bad Checksums
  7. Advanced Scanning Functions
    1. TCP SYN Scan
    2. TCP Connect Scan
    3. UDP Scan
    4. TCP NULL Scan
    5. TCP FIN Scan
    6. Xmas Scan
    7. TCP ACK Scan
    8. Custom TCP Scan
    9. IP Protocol Scan
    10. Send Raw Ethernet Packets
    11. Send IP Packets
  8. Timing Options
    1. Timing Templates
    2. Set the Packet TTL
    3. Minimum Number of Parallel Operations
    4. Maximum Number of Parallel Operations
    5. Minimum Host Group Size
    6. Maximum Host Group Size
    7. Maximum RTT Timeout
    8. Initial RTT TImeout
    9. Maximum Number of Retries
    10. Host Timeout
    11. Minimum Scan Delay
    12. Maximum Scan Delay
    13. Minimum Packet Rate
    14. Maximum Packet Rate
    15. Defeat Reset Rate Limits
  9. Output Options
    1. Save Output to a Text File
    2. Save Output to a XML File
    3. Grepable Output
    4. Output All Supported File Types
    5. Periodically Display Statistics
    6. 1337 Output
  10. Compare Scans
    1. Comparison Using Ndiff
    2. Ndiff Verbose Mode
    3. XML Output Mode
  11. Troubleshooting and Debugging
    1. Get Help
    2. Display Nmap Version
    3. Verbose Output
    4. Debugging
    5. Display Port State Reason
    6. Only Display Open Ports
    7. Trace Packets
    8. Display Host Networking
    9. Specify a Network Interface
  12. Nmap Scripting Engine
    1. Execute Individual Scripts
    2. Execute Multiple Scripts
    3. Execute Scripts by Category
    4. Execute Multiple Script Categories
    5. Troubleshoot Scripts
    6. Update the Script Database

What is Nmap?

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 uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running. It was designed to rapidly scan large networks, but works fine against single hosts.

How to Use Nmap

Nmap can be used in a variety of ways depending on the user's level of technical expertise.

Technical ExpertiseUsage
BeginnerZenmap the graphical user interface for Nmap
IntermediateCommand line
AdvancedPython scripting with the Python-Nmap package

Command Line

nmap [ <Scan Type> ...] [ <Options> ] { <target specification> }

Basic Scanning Techniques

The -s switch determines the type of scan to perform.

Nmap SwitchDescription
-sAACK scan
-sFFIN scan
-sIIDLE scan
-sLDNS scan (a.k.a. list scan)
-sNNULL scan
-sOProtocol scan
-sPPing scan
-sRRPC scan
-sSSYN scan
-sTTCP connect scan
-sWWindows scan
-sXXMAS scan

Scan a Single Target

nmap [target]

Scan Multiple Targets

nmap [target1, target2, etc]

Scan a List of Targets

nmap -iL [list.txt]

Scan a Range of Hosts

nmap [range of IP addresses]

Scan an Entire Subnet

nmap [ip address/cdir]

Scan Random Hosts

nmap -iR [number]

Exclude Targets From a Scan

nmap [targets] --exclude [targets]

Exclude Targets Using a List

nmap [targets] --excludefile [list.txt]

Perform an Aggresive Scan

nmap -A [target]

Scan an IPv6 Target

nmap -6 [target]

Port Scanning Options

Perform a Fast Scan

nmap -F [target]

Scan Specific Ports

nmap -p [port(s)] [target]

Scan Ports by Name

nmap -p [port name(s)] [target]

Scan Ports by Protocol

nmap -sU -sT -p U:[ports],T:[ports] [target]

Scan All Ports

nmap -p 1-65535 [target]

Scan Top Ports

nmap --top-ports [number] [target]

Perform a Sequential Port Scan

nmap -r [target]

Attempt to Guess an Unknown OS

nmap -O --osscan-guess [target]

Service Version Detection

nmap -sV [target]

Troubleshoot Version Scan

nmap -sV --version-trace [target]

Perform a RPC Scan

nmap -sR [target]

Discovery Options

Host Discovery The -p switch determines the type of ping to perform.

Nmap SwitchDescription
-PIICMP ping
-PoNo ping
-PSSYN ping
-PTTCP ping

Perform a Ping Only Scan

nmap -sn [target]

Do Not Ping

nmap -Pn [target]


nmap -PS [target]


nmap -PA [target]

UDP Ping

nmap -PU [target]


nmap -PY [target]

ICMP Echo Ping

nmap -PE [target]

ICMP Timestamp Ping

nmap -PP [target]

ICMP Address Mask Ping

nmap -PM [target]

IP Protocol Ping

nmap -PO [target]

ARP ping

nmap -PR [target]


nmap --traceroute [target]

Force Reverse DNS Resolution

nmap -R [target]

Disable Reverse DNS Resolution

nmap -n [target]

Alternative DNS Lookup

nmap --system-dns [target]

Manually Specify DNS Server

Can specify a single server or multiple.

nmap --dns-servers [servers] [target]

Create a Host List

nmap -sL [targets]

Port Specification and Scan Order

Nmap SwitchDescription

Service/Version Detection

Nmap SwitchDescription
-sVEnumerates software versions

Script Scan

Nmap SwitchDescription
-sCRun all default scripts

OS Detection

Nmap SwitchDescription

Timing and Performance

The -t switch determines the speed and stealth performed.

Nmap SwitchDescription
-T0Serial, slowest scan
-T1Serial, slow scan
-T2Serial, normal speed scan
-T3Parallel, normal speed scan
-T4Parallel, fast scan

Not specifying a T value will default to -T3, or normal speed.

Firewall Evasion Techniques

Firewall/IDS Evasion and Spoofing

Nmap SwitchDescription

Fragment Packets

nmap -f [target]

Specify a Specific MTU

nmap --mtu [MTU] [target]

Use a Decoy

nmap -D RND:[number] [target]

Idle Zombie Scan

nmap -sI [zombie] [target]

Manually Specify a Source Port

nmap --source-port [port] [target]

Append Random Data

nmap --data-length [size] [target]

Randomize Target Scan Order

nmap --randomize-hosts [target]

Spoof MAC Address

nmap --spoof-mac [MAC|0|vendor] [target]

Send Bad Checksums

nmap --badsum [target]

Advanced Scanning Functions


nmap -sS [target]

TCP Connect Scan

nmap -sT [target]

UDP Scan

nmap -sU [target]


nmap -sN [target]


nmap -sF [target]

Xmas Scan

nmap -sA [target]


nmap -sA [target]

Custom TCP Scan

nmap --scanflags [flags] [target]

IP Protocol Scan

nmap -sO [target]

Send Raw Ethernet Packets

nmap --send-eth [target]

Send IP Packets

nmap --send-ip [target]

Timing Options

Timing Templates

nmap -T[0-5] [target]

Set the Packet TTL

nmap --ttl [time] [target]

Minimum NUmber of Parallel Operations

nmap --min-parallelism [number] [target]

Maximum Number of Parallel Operations

nmap --max-parallelism [number] [target]

Minimum Host Group Size

nmap --min-hostgroup [number] [targets]

Maximum Host Group Size

nmap --max-hostgroup [number] [targets]

Maximum RTT Timeout

nmap --initial-rtt-timeout [time] [target]

Initial RTT Timeout

nmap --max-rtt-timeout [TTL] [target]

Maximum Number of Retries

nmap --max-retries [number] [target]

Host Timeout

nmap --host-timeout [time] [target]

Minimum Scan Delay

nmap --scan-delay [time] [target]

Maxmimum Scan Delay

nmap --max-scan-delay [time] [target]

Minimum Packet Rate

nmap --min-rate [number] [target]

Maximum Packet Rate

nmap --max-rate [number] [target]

Defeat Reset Rate Limits

nmap --defeat-rst-ratelimit [target]

Output Options

Nmap SwitchDescription
-oNNormal output
-oXXML output
-oANormal, XML, and Grepable format all at once

Save Output to a Text File

nmap -oN [scan.txt] [target]

Save Output to a XML File

nmap -oX [scan.xml] [target]

Grepable Output

nmap -oG [scan.txt] [target]

Output All Supported File Types

nmap -oA [path/filename] [target]

Periodically Display Statistics

nmap --stats-every [time] [target]

1337 Output

nmap -oS [scan.txt] [target]

Compare Scans

Comparison Using Ndiff

ndiff [scan1.xml] [scan2.xml]

Ndiff Verbose Mode

ndiff -v [scan1.xml] [scan2.xml]

XML Output Mode

ndiff --xml [scan1.xml] [scan2.xml]

Troubleshooting and Debugging

Get Help

nmap -h

Display Nmap Version

nmap -V

Verbose Output

nmap -v [target]


nmap -d [target]

Display Port State Reason

nmap --reason [target]

Only Display Open Ports

nmap --open [target]

Trace Packets

nmap --packet-trace [target]

Display Host Networking

nmap --iflist

Specify a Network Interface

nmap -e [interface] [target]

Nmap Scripting Engine

Execute Individual Scripts

nmap --script [script.nse] [target]

Execute Multiple Scripts

nmap --script [expression] [target]

Execute Scripts by Category

nmap --script [category] [target]

Execute Multiple Script Categories

nmap --script [category1,category2,etc]

Troubleshoot Scripts

nmap --script [script] --script-trace [target]

Update the Script Database

nmap --script-updatedb

Reference Sites