cyber-security-resources/cheat_sheets/NMAP_cheat_sheet.md

NMAP Cheat Sheet

Base nmap Syntax:

nmap [ScanType] [Options] {targets}

If no port range is specified, Nmap scans the 1,000 most popular ports.

• -p <port1>-<port2>: Scans a port range
• -p <port1>,<port2>,...: Scans a port list
• -pU:53,U:110,T20-445: Mix TCP and UDP
• -r: Scans linearly (does not randomize ports)
• --top-ports <n>: Scan n most popular ports
• -p-65535: Leaving off the initial port in range makes Nmap scan start at port 1
• -p-: Leaving off the end port in range makes Nmap scan all ports
• -F: (Fast (limited port) scan)

Port Status

• Open: This indicates that an application is listening for connections on this port.
• Closed: This indicates that the probes were received but there is no application listening on this port.
• Filtered: This indicates that the probes were not received and the state could not be established. It also indicates that the probes are being dropped by some kind of filtering.
• Unfiltered: This indicates that the probes were received but a state could not be established.
• Open/Filtered: This indicates that the port was filtered or open but Nmap couldn’t establish the state.
• Closed/Filtered: This indicates that the port was filtered or closed but Nmap couldn’t establish the state.

Scan Types

• -sn: Probe only (host discovery, not port scan)
• -sS: SYN Scan
• -sT: TCP Connect Scan
• -sU: UDP Scan
• -sV: Version Scan
• -O: Used for OS Detection/fingerprinting
• --scanflags: Sets custom list of TCP using URG ACK PSH RST SYN FIN in any order

Probing Options

• -Pn: Don't probe (assume all hosts are up)
• -PB: Default probe (TCP 80, 445 & ICMP)
• -PS<portlist> : Checks if ssytems are online by probing TCP ports
• -PE: Using ICMP Echo Request
• -PP: Using ICMP Timestamp Request
• -PM: Using ICMP Netmask Request

Timing Options

• -T0 (Paranoid): Very slow, used for IDS evasion
• -T1 (Sneaky): Quite slow, used for IDS evasion
• -T2 (Polite): Slows down to consume less bandwidth, runs ~10 times slower than default
• -T3 (Normal): Default, a dynamic timing model based on target responsiveness
• -T4 (Aggressive): Assumes a fast and reliable network and may overwhelm targets
• -T5 (Insane): Very aggressive; will likely overwhelm targets or miss open ports

Fine-Grained Timing Options

• --min-hostgroup/max-hostgroup <size> : Parallel host scan group sizes
• --min-parallelism/max-parallelism <numprobes>: Probes parallelization
• --min-rtt-timeout/max-rtttimeout/initial-rtt-timeout <time>: Specifies probe round trip time.
• --max-retries <tries>: Caps number of port scan probe retransmissions.
• --host-timeout <time>: Gives up on target after this long
• --scan-delay/--max-scan-delay <time>: Adjusts 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

Nmap Scripting Engine

The full list of Nmap Scripting Engine scripts: http://nmap.org/nsedoc/

nmap -sC runs default scripts...

Running individual or groups of scripts: nmap --script=<ScriptName>| <ScriptCategory>|<ScriptDir>

Using the list of script arguments: nmap --script-args=<Name1=Value1,...>

Updating the script database: nmap --script-updatedb

Some particularly useful scripts include:

• dns-zone-transfer: Attempts to pull a zone file (AXFR) from a DNS server.

$ nmap --script dns-zonetransfer.nse --script-args dns-zonetransfer.domain=<domain> -p53 <hosts>

• http-robots.txt: Harvests robots.txt files from discovered web servers.

$ nmap --script http-robots.txt <hosts>

• smb-brute: Attempts to determine valid username and password combinations via automated guessing.

$ nmap --script smb-brute.nse -p445 <hosts>

• smb-psexec: Attempts to run a series of programs on the target machine, using credentials provided as scriptargs.

$ nmap --script smb-psexec.nse –script-args=smbuser=<username>,smbpass=<password>[,config=<config>] -p445 <hosts>

Nmap Scripting Engine Categories

The most common Nmap scripting engine categories:

• auth: Utilize credentials or bypass authentication on target hosts.
• broadcast: Discover hosts not included on command line by broadcasting on local network.
• brute: Attempt to guess passwords on target systems, for a variety of protocols, including http, SNMP, IAX, MySQL, VNC, etc.
• default: Scripts run automatically when -sC or -A are used.
• discovery: Try to learn more information about target hosts through public sources of information, SNMP, directory services, and more.
• dos: May cause denial of service conditions in target hosts.
• exploit: Attempt to exploit target systems.
• external: Interact with third-party systems not included in target list.
• fuzzer: Send unexpected input in network protocol fields.
• intrusive: May crash target, consume excessive resources, or otherwise impact target machines in a malicious fashion.
• malware: Look for signs of malware infection on the target hosts.
• safe: Designed not to impact target in a negative fashion.
• version: Measure the version of software or protocols on the target hosts.
• vul: Measure whether target systems have a known vulnerability.

Output Options

• -oN: Standard Nmap output
• -oG: Greppable format
• -oX: XML format
• -oA: Generate Nmap, Greppable, and XML output files using basename for files

Additional Options

• -n: Disables reverse IP address lookups
• -6: Uses IPv6 only
• -A: Uses several features, including OS Detection, Version Detection, Script Scanning (default), and traceroute
• --reason: Displays the reason Nmap thinks that the port is open, closed, or filtered