nmap Command: Scan A Single IP Address or Host

How do I use nmap command to scan a single server using a host name or an IP address under Unix like operating systems?

You can use a nmap command to scan a single server using a host name such as server1.sxi.io or an IP address such as The syntax is:

nmap host-name-here


nmap IP-address-here

This example demonstrates port scanning using an IP address:
$ nmap
This example demonstrates port scanning using a host name:
$ nmap router
Sample outputs:

Fig.01: nmap command output

Understanding nmap command output

  • Not shown: 998 closed ports – By default nmap will show open ports only in the following format.
    • PORT – Port number with protocol.
    • STATE -The state is either open, filtered, closed, or unfiltered. Open state means that an application on the target machine is listening for connections/packets on that port. Filtered state means that a firewall, filter, or other network obstacle is blocking the port so that Nmap cannot tell whether it is open or closed.
    • SERVICE The service name. For example, the port # 22 is often used by ssh service such as OpenSSH server or the port # 80 is often used by a web server such as Apache.

To scan multiple IP addresses or hosts names:
$ nmap server1 server2 server2.nixcraft.net.in
$ nmap

Sample outputs:

Fig.02: nmap scan for multiple hosts

Tip: You can use nmap,2 instead of typing nmap, as both IP addresses are part of the same subnet

To speed up nmap execution pass the -T4 option as follows:
$ nmap -T4

Posted by: SXI ADMIN

The author is the creator of SXI LLC and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

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