Top 30 Basic NMAP Commands for Beginners

Nmap is a free tool that can be used to conduct various sorts of scans on networks. Normally, when people think of Nmap, they assume it’s used to conduct some sort of nefarious network reconnaissance in preparation for an attack. But as with all powerful tools, Nmap can be used for far more than breaking into networks.

One very important aspect of NMAP to remember is that these scans should be ran with Root or Administrator access depending on the type of system you are using. This is required because the scans send raw packets which require privileged system access.

Of the scan types listed below table, only the connect and ftp bounce scans can be ran without privileged access. The last thing to remember is that these scans can only be ran one at a time except if you are running a UDP and TCP scan at the same time.

Now let us take a look at the parameters NMAP uses to perform the different types of system scans. Remember the basic command line format for nmap is:

Syntax: nmap <scan type> <options> <target>

S.No	Title	Command Syntax
Target Selection
1	Scan a single IP	nmap 192.168.20.128
2	Scan a host	nmap www.example.com
3	Scan a range of IPs	nmap 192.168.20.120-128
4	Scan a subnet	nmap 192.168.20.2/24
5	Scan targets from Text file	nmap -iL ips.txt
Port Selection
6	Scan a single port	nmap -p 22 192.168.20.128
7	Scan a range of ports	nmap -p 1-100 192.168.20.128
8	Scan 100 common ports	nmap -F 192.168.20.128
9	Scan all ports	nmap -p- 192.168.20.128
10	Specify UDP or TCP scan	nmap -p U:137,T:139 192.168.20.128
Scan Types
11	Scan using TCP connect	nmap -sT 192.168.20.128
12	Scan using TCP SYN scan	nmap -sS 192.168.20.128
13	Scan UDP ports	nmap -sU -p 123,161,162 192.168.20.128
14	Scan Selected ports (Ignore Discovery)	nmap -Pn -F 192.168.20.128
Service and OS Detection
15	Detect OS and Services	nmap -A 192.168.20.128
16	Standard service detection	nmap -sV 192.168.20.128
17	Aggressive service detection	nmap -sV –version-intensity 5 192.168.20.128
Output Formats
18	Save default output to file	nmap -oN result.txt 192.168.20.128
19	Save results as XML	nmap -oX resultxml.xml 192.168.20.128
20	Save formatted results (Grep)	nmap -oG formattable.txt 192.168.20.128
21	Save in all formats	nmap -oA allformats 192.168.20.128
Scripting Engine
22	Scan using default safe scripts	nmap -sV -sC 192.168.20.128
23	Get help for a script	nmap –script-help=ssl-heartbleed
24	Scan using a specific script	nmap -sV -p 443 -script=ssl-heartbleed 192.168.20.133
25	Update script database	nmap –script-updatedb
Some Useful NSE Scripts
26	Scan for UDP DDOS reflectors	nmap -sU -A -PN -n -pU:19,53,123,161 -script=ntp-monlist,dns-recursion,snmp-sysdescr 192.168.20.2/24
27	Gather page titles from HTTP Servers	nmap –script=http-title 192.168.20.128
28	Get HTTP headers of web services	nmap –script=http-headers 192.168.20.128
29	Find web apps from known paths	nmap –script=http-enum 192.168.20.128
30	Find exposed Netbios servers	nmap -sU –script nbtstat.nse -p 137 192.168.20.128

The thing to remember is that running different types of scans may produce different results as firewalls may limit the responses allowed from the specific hosts it protects.

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