Nmap is one of the most popular network mappers in the infosec world. It’s utilized by cybersecurity professionals and newbies alike to audit and discover local and remote open ports, as well as hosts and network information.
Some of this tool’s best features are that it’s open-source, free, multi-platform and receives constant updates each year. It also has a big plus: it’s one of the most complete host and network scanners available. It includes a large set of options to enhance your scanning and mapping tasks, and brings with it an incredible community and comprehensive documentation to help you understand this tool from the very start. Nmap can be used to:
- Create a complete computer network map.
- Find remote IP addresses of any hosts.
- Get the OS system and software details.
- Detect open ports on local and remote systems.
- Audit server security standards.
- Find vulnerabilities on remote and local hosts.
It was mentioned in the Top 20 OSINT Tools article we published, and today we’ll explore a little bit more about this essential security tool with some practical terminal-based Nmap commands.
Best 15 Nmap command examples
Let’s get to know a few useful command-line based scans that can be performed using Nmap.
1. Basic Nmap Scan against IP or host
Now, if you want to scan a hostname, simply replace the IP for the host, as you see below:
These kinds of basic scans are perfect for your first steps when starting with Nmap.
2. Scan specific ports or scan entire port ranges on a local or remote server
nmap -p 1-65535 localhost
In this example, we scanned all 65535 ports for our localhost computer.
Nmap is able to scan all possible ports, but you can also scan specific ports, which will report faster results. See below:
nmap -p 80,443 22.214.171.124
3. Scan multiple IP addresses
Let’s try to scan multiple IP addresses. For this you need to use this syntax:
nmap 126.96.36.199 188.8.131.52
You can also scan consecutive IP addresses:
nmap -p 184.108.40.206,2,3,4
This will scan
4. Scan IP ranges
You can also use Nmap to scan entire CIDR IP ranges, for example:
nmap -p 220.127.116.11/28
This will scan 14 consecutive IP ranges, from
An alternative is to simply use this kind of range:
You can even use wildcards to scan the entire C class IP range, for example:
This will scan 256 IP addresses from
If you ever need to exclude certain IPs from the IP range scan, you can use the “–exclude” option, as you see below:
nmap -p 8.8.8.* --exclude 18.104.22.168
5. Scan the most popular ports
Using “–top-ports” parameter along with a specific number lets you scan the top X most common ports for that host, as we can see:
nmap --top-ports 20 192.168.1.106
Replace “20” with the desired number. Output example:
[root@securitytrails:~]nmap --top-ports 20 localhost Starting Nmap 6.40 ( http://nmap.org ) at 2018-10-01 10:02 EDT Nmap scan report for localhost (127.0.0.1) Host is up (0.000016s latency). Other addresses for localhost (not scanned): 127.0.0.1 PORT STATE SERVICE 21/tcp closed ftp 22/tcp closed ssh 23/tcp closed telnet 25/tcp closed smtp 53/tcp closed domain 80/tcp filtered http 110/tcp closed pop3 111/tcp closed rpcbind 135/tcp closed msrpc 139/tcp closed netbios-ssn 143/tcp closed imap 443/tcp filtered https 445/tcp closed microsoft-ds 993/tcp closed imaps 995/tcp closed pop3s 1723/tcp closed pptp 3306/tcp closed mysql 3389/tcp closed ms-wbt-server 5900/tcp closed vnc 8080/tcp closed http-proxy
6. Scan hosts and IP addresses reading from a text file
In this case, Nmap is also useful to read files that contain hosts and IPs inside.
Let’s suppose you create a list.txt file that contains these lines inside:
192.168.1.106 cloudflare.com microsoft.com securitytrails.com
The “-iL” parameter lets you read from that file, and scan all those hosts for you:
nmap -iL list.txt
7. Save your Nmap scan results to a file
On the other hand, in the following example we will not be reading from a file, but exporting/saving our results into a text file:
nmap -oN output.txt securitytrails.com
Nmap has the ability to export files into XML format as well, see the next example:
nmap -oX output.xml securitytrails.com
8. Disabling DNS name resolution
If you need to speed up your scans a little bit, you can always choose to disable reverse DNS resolution for all your scans. Just add the “-n” parameter.
[root@securitytrails:~]nmap -p 80 -n 22.214.171.124 Starting Nmap 7.60 ( https://nmap.org ) at 2018-10-01 09:15 -03 Nmap scan report for 126.96.36.199 Host is up (0.014s latency). PORT STATE SERVICE 80/tcp filtered http
See the difference with a normal DNS-resolution enabled scan:
[root@securitytrails:~]nmap -p 80 188.8.131.52 Starting Nmap 7.60 ( https://nmap.org ) at 2018-10-01 09:15 -03 Nmap scan report for google-public-dns-a.google.com (184.108.40.206) Host is up (0.014s latency). PORT STATE SERVICE 80/tcp filtered http
9. Scan + OS and service detection with fast execution
Using the “-A” parameter enables you to perform OS and service detection, and at the same time we are combining this with “-T4” for faster execution. See the example below:
nmap -A -T4 cloudflare.com
This is the output we got for this test:
10. Detect service/daemon versions
This can be done by using -sV parameters
nmap -sV localhost
As you can see here:
[root@securitytrails:~]nmap -sV localhost Starting Nmap 7.60 ( https://nmap.org ) at 2018-10-01 09:28 -03 Nmap scan report for localhost (127.0.0.1) Host is up (0.000020s latency). Other addresses for localhost (not scanned): ::1 Not shown: 997 closed ports PORT STATE SERVICE VERSION 111/tcp open rpcbind 2-4 (RPC #100000) 631/tcp open ipp CUPS 2.2 902/tcp open ssl/vmware-auth VMware Authentication Daemon 1.10 (Uses VNC, SOAP) Service detection performed. Please report any incorrect results at https://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 7.96 seconds
11. Scan using TCP or UDP protocols
One of the things we love most about Nmap is the fact that it works for both TCP and UDP protocols. And while most services run on TCP, you can also get a great advantage by scanning UDP-based services. Let’s see some examples.
Standard TCP scanning output:
[root@securitytrails:~]nmap -sT 192.168.1.1 Starting Nmap 7.60 ( https://nmap.org ) at 2018-10-01 09:33 -03 Nmap scan report for 192.168.1.1 Host is up (0.58s latency). Not shown: 995 closed ports PORT STATE SERVICE 80/tcp open http 1900/tcp open upnp 20005/tcp open btx 49152/tcp open unknown 49153/tcp open unknown Nmap done: 1 IP address (1 host up) scanned in 1.43 seconds
UDP scanning results using “-sU” parameter:
[root@securitytrails:~]nmap -sU localhost Starting Nmap 7.60 ( https://nmap.org ) at 2018-10-01 09:37 -03 Nmap scan report for localhost (127.0.0.1) Host is up (0.000021s latency). Other addresses for localhost (not scanned): ::1 Not shown: 997 closed ports PORT STATE SERVICE 68/udp open|filtered dhcpc 111/udp open rpcbind 5353/udp open|filtered zeroconf
12. CVE detection using Nmap
One of Nmap’s greatest features that not all the network and systems administrators know about is something called “Nmap Scripting Engine” (known as NSE). This scripting engine allows users to use a pre-defined set of scripts, or write their own using Lua programming language.
Using NSE is crucial in order to automate system and vulnerability scans. For example, if you want to run a full vulnerability test against your target, you can use these parameters:
nmap -Pn --script vuln 192.168.1.105
[root@securitytrails:~]nmap -Pn --script vuln 192.168.1.105 Starting Nmap 7.60 ( https://nmap.org ) at 2018-10-01 09:46 -03 Pre-scan script results: | broadcast-avahi-dos: | Discovered hosts: | 220.127.116.11 | After NULL UDP avahi packet DoS (CVE-2011-1002). |_ Hosts are all up (not vulnerable). Nmap scan report for 192.168.1.105 Host is up (0.00032s latency). Not shown: 995 closed ports PORT STATE SERVICE 80/tcp open http |_http-csrf: Couldn't find any CSRF vulnerabilities. |_http-dombased-xss: Couldn't find any DOM based XSS. | http-slowloris-check: | VULNERABLE: | Slowloris DOS attack | State: LIKELY VULNERABLE | IDs: CVE:CVE-2007-6750 | Slowloris tries to keep many connections to the target web server open and hold | them open as long as possible. It accomplishes this by opening connections to | the target web server and sending a partial request. By doing so, it starves | the http server's resources causing Denial Of Service. | | Disclosure date: 2009-09-17 | References: | http://ha.ckers.org/slowloris/ |_ https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-6750 |_http-stored-xss: Couldn't find any stored XSS vulnerabilities. |_http-vuln-cve2014-3704: ERROR: Script execution failed (use -d to debug) 1900/tcp open upnp 20005/tcp open btx 49152/tcp open unknown 49153/tcp open unknown
As you can see, in this vulnerability test we were able to detect one CVE (Slowloris DOS attack).
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13. Launching DOS with Nmap
Nmap features never seem to end, and thanks to the NSE, that even allows us to launch DOS attacks against our network testings.
In our previous example (#12) we found the host was vulnerable to Slowloris attack, and now we’ll try to exploit that vulnerability by launching a DOS attack in a forever loop:
nmap 192.168.1.105 -max-parallelism 800 -Pn --script http-slowloris --script-args http-slowloris.runforever=true
14. Launching brute force attacks
NSE is really fascinating – it contains scripts for everything you can imagine. See the next three examples of BFA against WordPress, MSSQL, and FTP server:
WordPress brute force attack:
nmap -sV --script http-wordpress-brute --script-args 'userdb=users.txt,passdb=passwds.txt,http-wordpress-brute.hostname=domain.com, http-wordpress-brute.threads=3,brute.firstonly=true' 192.168.1.105
Brute force attack against MS-SQL:
nmap -p 1433 --script ms-sql-brute --script-args userdb=customuser.txt,passdb=custompass.txt 192.168.1.105
FTP brute force attack:
nmap --script ftp-brute -p 21 192.168.1.105
15. Detecting malware infections on remote hosts
Nmap is able to detect malware and backdoors by running extensive tests on a few popular OS services like on Identd, Proftpd, Vsftpd, IRC, SMB, and SMTP. It also has a module to check for popular malware signs inside remote servers and integrates Google’s Safe Browsing and VirusTotal databases as well.
A common malware scan can be performed by using:
nmap -sV --script=http-malware-host 192.168.1.105
Or using Google’s Malware check:
nmap -p80 --script http-google-malware infectedsite.com
80/tcp open http |_http-google-malware.nse: Host is known for distributing malware.
Nmap is one of the most complete and accurate port scanners used by infosec professionals today. With it, you can perform simple port scan tasks or use its powerful scripting engine to launch DOS attacks, detect malware or brute force testings on remote and local servers.
Today we covered the top fifteen Nmap commands to scan remote hosts, but there’s a lot more to discover if you’re starting to use Nmap in your OSINT strategy.