Network Scanning
Core Technology
Network scanning may carry a negative connotation, but it doesn't mean you shouldn't look for weak spots in your network.
Imagine you are administering a small office or home network. Perhaps you want to know what hosts in this subnet are currently online, or which service that Internet of Things (IoT) device keeps open to the world. Network scanners are tools built to do just that.
Even if a host is properly secured and has unused ports closed, a network scanner may tell quite a lot about it. There are slight discrepancies in how popular operating systems (OSs) implement network protocols such as TCP. A tool that knows these nuances can make an educated guess about which OS the host runs. This is known as OS fingerprinting, and many network scanners implement it as well. Sometimes, it can even give you an uptime estimate!
As you guessed already, this Core Tech is about network scanning. Before we dive in, a usual word of warning: As with many technologies, network scanning can be used for good and for evil. Many network attacks begin with it, so it is deemed illegal in some provider and corporate networks. Never scan a network you don't really own unless you have permission to do so. When in doubt, a purpose-built scan target, scanme.nmap.org, is a good choice.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

News
-
openSUSE Tumbleweed Ditches AppArmor for SELinux
If you're an openSUSE Tumbleweed user, you can expect a major change to the distribution.
-
Plasma 6.3 Now Available
Plasma desktop v6.3 has a couple of pretty nifty tricks up its sleeve.
-
LibreOffice 25.2 Has Arrived
If you've been hoping for a release that offers more UI customizations, you're in for a treat.
-
TuxCare Has a Big AlmaLinux 9 Announcement in Store
TuxCare announced it has successfully completed a Security Technical Implementation Guide for AlmaLinux OS 9.
-
First Release Candidate for Linux Kernel 6.14 Now Available
Linus Torvalds has officially released the first release candidate for kernel 6.14 and it includes over 500,000 lines of modified code, making for a small release.
-
System76 Refreshes Meerkat Mini PC
If you're looking for a small form factor PC powered by Linux, System76 has exactly what you need in the Meerkat mini PC.
-
Gnome 48 Alpha Ready for Testing
The latest Gnome desktop alpha is now available with plenty of new features and improvements.
-
Wine 10 Includes Plenty to Excite Users
With its latest release, Wine has the usual crop of bug fixes and improvements, along with some exciting new features.
-
Linux Kernel 6.13 Offers Improvements for AMD/Apple Users
The latest Linux kernel is now available, and it includes plenty of improvements, especially for those who use AMD or Apple-based systems.
-
Gnome 48 Debuts New Audio Player
To date, the audio player found within the Gnome desktop has been meh at best, but with the upcoming release that all changes.