Nmap null scan example

We have published a tutorial showing different ways to scan all ports using Nmap. One of these methods to scan all ports on a target requires the implementation of the -p- option as shown in the following example. The following example shows a NULL scan against linuxhint. The Xmas scan with Nmap was deeply explained in this article. Nmap contains a suite of scripts with additional functionalities.

This suite is known as Nmap NSE. Two Windows XP computers were found, great candidates for a Idle scan which will be explained later below in this tutorial. The following example shows how to search for a zombie candidate to execute an Idle scan by scanning the last octet of the This example shows how to use the Nmap scripting engine to bruteforce the target ssh.

As you can see, NSE will read a list including username and password pairs. Of course, you can provide NSE your custom list. It prints the scan report for UDP port only. You can specify a range of ports with -p option to scan using nmap command. It scans for all the available ports between the specified range. It is useful to debug routing problems and device mischaracterization.

You must specify IPv6 address in order to perform IPv6 scanning. Otherwise, it will fail to resolve the address. You can specify the maximum number of IP addresses you wish to scan using -iR option. It scans the specified number of random IP addresses. The number 0 is used to set the unlimited number of IP addresses. It only prints out the list of hosts that responded to the scan. It is also called a "ping scan". These are the most used nmap command examples in Linux.

It is a powerful tool that is also used by hackers. You can use this tool to get detailed information on the network, find the number of ports available on the network, detect OS and services and get the list of live hosts.

If my articles on GoLinuxCloud has helped you, kindly consider buying me a coffee as a token of appreciation. Don't count on this though—most modern IDS products can be configured to detect them. The big downside is that not all systems follow RFC to the letter. A number of systems send RST responses to the probes regardless of whether the port is open or not. This causes all of the ports to be labeled closed. This scan does work against most Unix-based systems though.

Since Nmap OS detection tests for this quirk, you can learn whether the scan works against a particular type of system by examining the nmap-os-db file. If the T2 line is longer, the system violated the RFC by sending a response and these scans won't work. Another downside of these scans is that they can't distinguish open ports from certain filtered ones. But most filters simply drop banned probes without any response, making the ports appear open. Since Nmap cannot be sure which is the case, it marks non-responsive ports as open filtered.

Adding version detection -sV can disambiguate as it does with UDP scans, but that defeats much of the stealthy nature of this scan. If you are willing and able to connect to the ports anyway, you might as well use a SYN scan. Using these scan methods is simple. Just add the -sN , -sF , or -sX options to specify the scan type.