Automatically monitoring your home network
The Watcher
To discover possibly undesirable arrivals and departures on their networks, a Perl daemon periodically stores the data from Nmap scans and passes them on to Nagios via a built-in web interface.
The practical Nmap network scanner is used not only by the bad boys in exciting thrillers to detect intrusion targets [1], it also tells admins what devices are actually reachable on their home networks. If you regularly launch Nmap on your subnets and compare the output, you can keep track of newly added or removed devices and proactively ward off nasty surprises.
The fact that nmap has a -oX option that tells it to output the results in XML format is something I was unaware of until I read an Nmap manual that was recently released as a Kindle book [2]. Because an Nmap scan across multiple networks can take a few minutes, I got the idea of building a daemon that finds all the nodes once an hour, keeps the data in memory, and sends it via a built-in web server to requesting clients, such as a Nagios script.
Lean Script Defines the Search Space
The script in Listing 1 [3] does this, mainly by resorting to the NmapServer module (which is loaded in line 7 and discussed later on) and its start() method. Before the call, it defines the IP range of the home network that nmap needs to scan in the constructor – in this case the subnets are 192.168.14.x and 192.168.27.x.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia
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
-
Fedora 43 Has Finally Landed
The Fedora Linux developers have announced their latest release, Fedora 43.
-
KDE Unleashes Plasma 6.5
The Plasma 6.5 desktop environment is now available with new features, improvements, and the usual bug fixes.
-
Xubuntu Site Possibly Hacked
It appears that the Xubuntu site was hacked and briefly served up a malicious ZIP file from its download page.
-
LMDE 7 Now Available
Linux Mint Debian Edition, version 7, has been officially released and is based on upstream Debian.
-
Linux Kernel 6.16 Reaches EOL
Linux kernel 6.16 has reached its end of life, which means you'll need to upgrade to the next stable release, Linux kernel 6.17.
-
Amazon Ditches Android for a Linux-Based OS
Amazon has migrated from Android to the Linux-based Vega OS for its Fire TV.
-
Cairo Dock 3.6 Now Available for More Compositors
If you're a fan of third-party desktop docks, then the latest release of Cairo Dock with Wayland support is for you.
-
System76 Unleashes Pop!_OS 24.04 Beta
System76's first beta of Pop!_OS 24.04 is an impressive feat.
-
Linux Kernel 6.17 is Available
Linus Torvalds has announced that the latest kernel has been released with plenty of core improvements and even more hardware support.
-
Kali Linux 2025.3 Released with New Hacking Tools
If you're a Kali Linux fan, you'll be glad to know that the third release of this famous pen-testing distribution is now available with updates for key components.