Target Specification
Switch | Example | Description |
|---|---|---|
nmap 192.168.1.1 | Scan a single IP | |
nmap 192.168.1.1 192.168.2.1 | Scan specific IPs | |
nmap 192.168.1.1-254 | Scan a range | |
nmap scanme.nmap.org | Scan a domain | |
nmap 192.168.1.0/24 | Scan using CIDR notation | |
-iL | nmap -iL targets.txt | Scan targets from a file |
-iR | nmap -iR 100 | Scan 100 random hosts |
--exclude | nmap --exclude 192.168.1.1 | Exclude listed hosts |
Scan Techniques
Scan Techniques
Switch | Example | Description |
|---|---|---|
-sS | nmap 192.168.1.1 -sS | TCP SYN port scan (Default) |
-sT | nmap 192.168.1.1 -sT | TCP connect port scan |
-sU | nmap 192.168.1.1 -sU | UDP port scan |
-sA | nmap 192.168.1.1 -sA | TCP ACK port scan |
-sW | nmap 192.168.1.1 -sW | TCP Window port scan |
-sM | nmap 192.168.1.1 -sM | TCP Maimon port scan |
Host Discovery
Host Discovery
Switch | Example | Description |
|---|---|---|
-sL | nmap 192.168.1.1-3 -sL | No Scan. List targets only |
-sn | nmap 192.168.1.1/24 -sn | Disable port scanning. Host discovery only. |
-Pn | nmap 192.168.1.1-5 -Pn | Disable host discovery. Port scan only. |
-PS | nmap 192.168.1.1-5 -PS22-25,80 | TCP SYN discovery on port x. Port 80 by default |
-PA | nmap 192.168.1.1-5 -PA22-25,80 | TCP ACK discovery on port x. Port 80 by default |
-PU | nmap 192.168.1.1-5 -PU53 | UDP discovery on port x. Port 40125 by default |
-PR | nmap 192.168.1.1-1/24 -PR | ARP discovery on local network |
-n | nmap 192.168.1.1 -n | Never do DNS resolution |
Port Specification
Port Specification
Switch | Example | Description |
|---|---|---|
-p | nmap 192.168.1.1 -p 21 | Port scan for port x |
-p | nmap 192.168.1.1 -p 21-100 | Port range |
-p | nmap 192.168.1.1 -p U:53,T:21-25,80 | Port scan multiple TCP and UDP ports |
-p- | nmap 192.168.1.1 -p- | Port scan all ports |
-p | nmap 192.168.1.1 -p http,https | Port scan from service name |
-F | nmap 192.168.1.1 -F | Fast port scan (100 ports) |
--top-ports | nmap 192.168.1.1 --top-ports 2000 | Port scan the top x ports |
-p-65535 | nmap 192.168.1.1 -p-65535 | Leaving off initial port in range |
-p0- | nmap 192.168.1.1 -p0- | Leaving off end port in range makes the scan go through to port 65535 |
Service and Version Detection
Service and Version Detection
Switch | Example | Description |
|---|---|---|
-sV | nmap 192.168.1.1 -sV | Attempts to determine the version of the service running on port |
-sV --version-intensity | nmap 192.168.1.1 -sV --version-intensity 8 | Intensity level 0 to 9. Higher number increases possibility of correctness |
-sV --version-light | nmap 192.168.1.1 -sV --version-light | Enable light mode. Lower possibility of correctness. Faster |
-sV --version-all | nmap 192.168.1.1 -sV --version-all | Enable intensity level 9. Higher possibility of correctness. Slower |
-A | nmap 192.168.1.1 -A | Enables OS detection, version detection, script scanning, and traceroute |
OS Detection
OS Detection
Switch | Example | Description |
|---|---|---|
-O | nmap 192.168.1.1 -O | Remote OS detection using TCP/IP |
-O --osscan-limit | nmap 192.168.1.1 -O --osscan-limit | If at least one open and one closed |
-O --osscan-guess | nmap 192.168.1.1 -O --osscan-guess | Makes Nmap guess more aggressively |
-O --max-os-tries | nmap 192.168.1.1 -O --max-os-tries 1 | Set the maximum number x of OS |
-A | nmap 192.168.1.1 -A | Enables OS detection, version detection, script scanning, and traceroute |
Timing and Performance
Timing and Performance
Switch | Example | Description |
|---|---|---|
-T0 | nmap 192.168.1.1 -T0 | Paranoid (0) Intrusion Detection |
-T1 | nmap 192.168.1.1 -T1 | Sneaky (1) Intrusion Detection System |
-T2 | nmap 192.168.1.1 -T2 | Polite (2) slows down the scan to use |
-T3 | nmap 192.168.1.1 -T3 | Normal (3) which is default speed |
-T4 | nmap 192.168.1.1 -T4 | Aggressive (4) speeds scans; assumes |
-T5 | nmap 192.168.1.1 -T5 | Insane (5) speeds scan; assumes you |
Switch | Example input | Description |
|---|---|---|
--host-timeout <time> | 1s; 4m; 2h | Give up on target after this long |
--min-rtt-timeout/max-rtt-timeout/initial-rtt-timeout <time> | 1s; 4m; 2h | Specifies probe round trip time |
--min-hostgroup/max-hostgroup <size<size> | 50; 1024 | Parallel host scan group |
--min-parallelism/max-parallelism <numprobes> | 10; 1 | Probe parallelization |
--scan-delay/--max-scan-delay <time> | 20ms; 2s; 4m; 5h | Adjust delay between probes |
--max-retries <tries> | 3 | Specify the maximum number |
--min-rate <number> | 100 | Send packets no slower than <numberr> per second |
--max-rate <number> | 100 | Send packets no faster than <number> per second |
NSE Scripts
NSE Scripts
Switch | Example | Description |
|---|---|---|
-sC | nmap 192.168.1.1 -sC | Scan with default NSE scripts. Considered useful for discovery and safe |
--script default | nmap 192.168.1.1 --script default | Scan with default NSE scripts. Considered useful for discovery and safe |
--script | nmap 192.168.1.1 --script=banner | Scan with a single script. Example banner |
--script | nmap 192.168.1.1 --script=http* | Scan with a wildcard. Example http |
--script | nmap 192.168.1.1 --script=http,banner | Scan with two scripts. Example http and banner |
--script | nmap 192.168.1.1 --script "not intrusive" | Scan default, but remove intrusive scripts |
--script-args | nmap --script snmp-sysdescr --script-args snmpcommunity=admin 192.168.1.1 | NSE script with arguments |
Useful NSE Script Examples
Command | Description |
|---|---|
nmap -Pn --script=http-sitemap-generator scanme.nmap.org | http site map generator |
nmap -n -Pn -p 80 --open -sV -vvv --script banner,http-title -iR 1000 | Fast search for random web servers |
nmap -Pn --script=dns-brute domain.com | Brute forces DNS hostnames guessing subdomains |
nmap -n -Pn -vv -O -sV --script smb-enum*,smb-ls,smb-mbenum,smb-os-discovery,smb-s*,smb-vuln*,smbv2* -vv 192.168.1.1 | Safe SMB scripts to run |
nmap --script whois* domain.com | Whois query |
nmap -p80 --script http-unsafe-output-escaping scanme.nmap.org | Detect cross site scripting vulnerabilities |
nmap -p80 --script http-sql-injection scanme.nmap.org | Check for SQL injections |
Firewall / IDS Evasion and Spoofing
Firewall / IDS Evasion and Spoofing
Switch | Example | Description |
|---|---|---|
-f | nmap 192.168.1.1 -f | Requested scan (including ping scans) use tiny fragmented IP packets. Harder for packet filters |
--mtu | nmap 192.168.1.1 --mtu 32 | Set your own offset size |
-D | nmap -D 192.168.1.101,192.168.1.102, | Send scans from spoofed IPs |
-D | nmap -D decoy-ip1,decoy-ip2,your-own-ip,decoy-ip3,decoy-ip4 remote-host-ip | Above example explained |
-S | nmap -S www.microsoft.com www.facebook.com | Scan Facebook from Microsoft (-e eth0 -Pn may be required) |
-g | nmap -g 53 192.168.1.1 | Use given source port number |
--proxies | nmap --proxies http://192.168.1.1:8080, http://192.168.1.2:8080 192.168.1.1 | Relay connections through HTTP/SOCKS4 proxies |
--data-length | nmap --data-length 200 192.168.1.1 | Appends random data to sent packets |
Example IDS Evasion command
nmap -f -t 0 -n -Pn –data-length 200 -D 192.168.1.101,192.168.1.102,192.168.1.103,192.168.1.23 192.168.1.1
Output
Output
Switch | Example | Description |
|---|---|---|
-oN | nmap 192.168.1.1 -oN normal.file | Normal output to the file normal.file |
-oX | nmap 192.168.1.1 -oX xml.file | XML output to the file xml.file |
-oG | nmap 192.168.1.1 -oG grep.file | Grepable output to the file grep.file |
-oA | nmap 192.168.1.1 -oA results | Output in the three major formats at once |
-oG - | nmap 192.168.1.1 -oG - | Grepable output to screen. -oN -, -oX - also usable |
--append-output | nmap 192.168.1.1 -oN file.file --append-output | Append a scan to a previous scan file |
-v | nmap 192.168.1.1 -v | Increase the verbosity level (use -vv or more for greater effect) |
-d | nmap 192.168.1.1 -d | Increase debugging level (use -dd or more for greater effect) |
--reason | nmap 192.168.1.1 --reason | Display the reason a port is in a particular state, same output as -vv |
--open | nmap 192.168.1.1 --open | Only show open (or possibly open) ports |
--packet-trace | nmap 192.168.1.1 -T4 --packet-trace | Show all packets sent and received |
--iflist | nmap --iflist | Shows the host interfaces and routes |
--resume | nmap --resume results.file | Resume a scan |
Helpful Nmap Output examples
Command | Description |
|---|---|
nmap -p80 -sV -oG - --open 192.168.1.1/24 | grep open | Scan for web servers and grep to show which IPs are running web servers |
nmap -iR 10 -n -oX out.xml | grep "Nmap" | cut -d " " -f5 > live-hosts.txt | Generate a list of the IPs of live hosts |
nmap -iR 10 -n -oX out2.xml | grep "Nmap" | cut -d " " -f5 >> live-hosts.txt | Append IP to the list of live hosts |
ndiff scanl.xml scan2.xml | Compare output from nmap using the ndif |
xsltproc nmap.xml -o nmap.html | Convert nmap xml files to html files |
grep " open " results.nmap | sed -r 's/ +/ /g' | sort | uniq -c | sort -rn | less | Reverse sorted list of how often ports turn up |
Miscellaneous Options
Miscellaneous Options
Switch | Example | Description |
|---|---|---|
-6 | nmap -6 2607:f0d0:1002:51::4 | Enable IPv6 scanning |
-h | nmap -h | nmap help screen |
Other Useful Nmap Commands
Other Useful Nmap Commands
Command | Description |
|---|---|
nmap -iR 10 -PS22-25,80,113,1050,35000 -v -sn | Discovery only on ports x, no port scan |
nmap 192.168.1.1-1/24 -PR -sn -vv | Arp discovery only on local network, no port scan |
nmap -iR 10 -sn -traceroute | Traceroute to random targets, no port scan |
nmap 192.168.1.1-50 -sL --dns-server 192.168.1.1 | Query the Internal DNS for hosts, list targets only |
Nathan House
Nathan House is the founder and CEO of Station X a cyber security training and consultancy company. He has over 25 years experience in cyber security where he has advised some of largest companies in the world, assuring security on multi-million and multi-billion pound projects. Nathan is the author of the popular "The Complete Cyber Security Course" which has been taken by over 200,000 students in 195 countries. Winner of the AI "Cyber Security Educator of the Year 2020" award. Over the years he has spoken at a number of security conferences, developed free security tools, and discovered serious security vulnerabilities in leading applications. PGP Fingerprint : CBA3FBF729FB00CB21D64FB00E7955AE6E37FEF1
Thanks a lot for the information. it is very useful.
That will be a helpful tipsheet. Thank you so much. I can learn more about it. looking forward to the hacking course from you.
Looking forward to it. I use nmap most days but only use a limited number of switches.
Keep the good hands-on stuff coming
Thank you very much in deed, very useful, I will buy your course on nmap, I want to insist about a Firewall course there aren’t around, I guess it is a good investment for you, I bought already all your courses and they are the best! Please keep going!
Great news.
In expectation of this course.
As usual ,
Thanks for what you doing.
I think this is very Useful,Thank you soo much.Am enjoying the training and practice.
Love it. Thank you Nathan!
Muchas gracias ,,, me fue de utilidad,,,
How to test .net Web services using ZenMap
You will need to expand on this question as I’m not clear what you are asking?
Thank you for sharing this information!
Thank you for this cheatsheet.
I think there is a mistake concerning the -sS switch. It is not the default one.
Normally, -sT is the default one and -sS needs root privileges.
Default with root. I assume you are running as root!
Hi
This is very helpful. Thanks a lot!
Sir this is very helpfull and very important for firewall point of view,
But what about port knock if a system or server is using port knock to active its any port for a client. Any method by nmap that can bypass port knock.
Thank you
The basic port knocking method uses a fixed sequence of ports. This method is not protected cryptographically so there are the following attacks possible:
brute-force — If you use the full range of possible ports 1—65535 then even very short knocking sequences give impressive number of combinations to test. For example for 3 knocks with randomly generated sequence it is 65535³ ≈ 2.8×10¹⁴. Another aspect to consider is that the port which will open after the knocking could be unknown so the attacker would have to repeatedly scan the ports during the port knocking attempts. — The number of combinations to try can be lowered if some information about the ports being used is known (for example a subset of ports) or if there is a successful random number generator attack.
Measure against such attacks except securing the mentioned possible vulnerabilities could be disabling of the access from the attacker source IP address after certain number of unsuccessful attempts during certain time period. Unfortunately this makes the system vulnerable to DoS attacks by attacker locking your access by using your IP address as a spoofed source address.
sniffing — The port knocking sequence is not protected cryptographically so an attacker can sniff the successful port knocking sequence. The port knocking sequence could also leak from logs of the destination system itself of from a network monitoring system.
Measure against this attack is use of one-time knocking sequences (analogy of one-time passwords). The one-time sequence could be a hash computed from a secret and some of the following: source IP address, time, event counter etc.
man in the middle — Captured one-time knocking sequences cannot be reused but a port-knocking access can be exploited by a man-in-the-middle attack. The attacker in the path of your communication (possibly redirected) can relay your successful communication, see and modify anything.
The port-knocking itself is performed by one-way communication as such it cannot be protected against MITM. Also the communication following the port knocking must be secured against MITM to retain the security. To ensure this we can use standard encrypted protocols like SSL or SSH.
Great stuff!
Can you please help me understand the main difference between
nmap 192.168.1.1 -O and nmap 192.168.1.1 -A
nmap 192.168.1.1 -O = Remote OS detection using TCP/IP stack fingerprinting
nmap 192.168.1.1 -A = Enables OS detection PLUS – version detection, script scanning, and traceroute
So -O is only OS detection, -A is OS detection PLUS – version detection, script scanning, and traceroute
Thanks Man , That’s Help me a lot .
i wanna ask , what is the main different between -sn AND -Pn ;
what is the network discovery do exactly and port scan !!
-sn just finds hosts that are up. No port scan. -Pn is the opposite. No host discovery. Port scan if it appears up or not.
hi sir ,
i just wanna know , is there any benefit for this -sL option ? and when do i use -P0 ?
-sL does no scan and just lists targets only to be scanned.
The list scan is a degenerate form of host discovery that simply lists each host of the network(s) specified, without sending any packets to the target hosts. By default, Nmap still does reverse-DNS resolution on the hosts to learn their names. It is often surprising how much useful information simple hostnames give out. For example, fw.chi is the name of one company’s Chicago firewall. Nmap also reports the total number of IP addresses at the end. The list scan is a good sanity check to ensure that you have proper IP addresses for your targets. If the hosts sport domain names you do not recognize, it is worth investigating further to prevent scanning the wrong company’s network. Since the idea is to simply print a list of target hosts, options for higher level functionality such as port scanning, OS detection, or ping scanning cannot be combined with this. If you wish to disable ping scanning while still performing such higher level functionality, read up on the -Pn (skip ping) option.
-PO (IP Protocol Ping)
One of the newer host discovery options is the IP protocol ping, which sends IP packets with the specified protocol number set in their IP header. The protocol list takes the same format as do port lists in the previously discussed TCP, UDP and SCTP host discovery options. If no protocols are specified, the default is to send multiple IP packets for ICMP (protocol 1), IGMP (protocol 2), and IP-in-IP (protocol 4). The default protocols can be configured at compile-time by changingDEFAULT_PROTO_PROBE_PORT_SPEC in nmap.h. Note that for the ICMP, IGMP, TCP (protocol 6), UDP (protocol 17) and SCTP (protocol 132), the packets are sent with the proper protocol headers while other protocols are sent with no additional data beyond the IP header (unless any of –data, –data-string, or –data-length options are specified). This host discovery method looks for either responses using the same protocol as a probe, or ICMP protocol unreachable messages which signify that the given protocol isn’t supported on the destination host. Either type of response signifies that the target host is alive.
Yea i read this , but i dont get it , in short words give me what is -P0 used for ??
Do you know what IP protocols are? like 1 ICMP Internet Control Message Protocol RFC 792, 2 IGMP Internet Group Management Protocol RFC 1112.
It sends IP packets with the specified protocol number set in the IP header. It’s an alternative discovery method.
I AM YOUR BIG FAN SIR..LOVE U
Great! I was just wondering “gosh, if there could be a pdf version and – woah, there is”
Gald to help!
sirr i need your help
i thing u help mee
How can I help?
Very good article
Thank you Nathan.
Very great article I tried to build, an online command simulator
This is so awesome! I’m taking your course now and my only regret is I didn’t do this sooner! This could’ve saved me soooo much headache and time! But it’s ok! Best way to learn is through error lol. Now that I know all the things NOT to do, you are showing the way. Thank you Mr. House.
Glad you are enjoying the course! 🙂
Great article and quite good presentation
I built and online version of nmap here so such commands
like described here i like them.
man u may live long , may God bless u ok
Appreciate it Arthur.
When was the last time you updated your course Nathan?
nmap doesn’t change quickly in terms of how you use the tool. The last major release Nmap 7.00 was November 9, 2015. We are still on 7 now. The course was created well after this.
Sir, plez show bobs en vagene.. thank kindly sir I owe you, you r best god bless sir
I assume you mean “Bobs and Vegana”. Any reason I should do that?
Wow – this is awesome. I was in the throes of creating my own, and well, yours looks much better than mine. Much appreciated!
Thank you Tim
thank you sir nathan!
Thank you very much Sir, for this NMAP Cheat sheet, I am from India, and enrolled in your the Complete Cyber Security Volume 1,2,3,4, loved your content and way of explaining #StaySafeOnline
My pleasure. Great to have you on the course.
What does nmap do other than scan for vunerailitites?
It’s not really a vulnerability scanner, although it can do that with a script. It is for discovering hosts and open ports.
thank you for the detailed nmap cheat sheet.
N.e.e.d.s