Sunday, January 06, 2013

Where Has All the Bandwidth Gone? Free Apps to Inventory Your Home Network

Everything is Internet-capable these days, from handheld gaming devices to refrigerators with built-in Pandora.  Surprisingly, however, most folks don't really know what they have, or haven't, connected to their home network, especially where Wi-Fi networking is concerned.  Well, this isn't necessarily a good thing, especially if your neighbors are leeching your bandwidth through an unprotected wireless access point (Shame on them, and shame on you for not securing it properly!), so here are three free apps that can, among other things, take a quick-and-easy inventory of your home network.

First, for the Windows platform, the folks at Fluke Networks offer IP Inspector.  This is a nice little app that simply reports every active device on the specified network, and does so rather quickly; it required less than 1 minute to scan my /24 home network.  IP Inspector can also do some limited port scanning; however, it only provides a list of 30 or so commonly used ports.  You can grab IP Inspector from Fluke's promotions page; while you're there, you might want to take a look at some of their other free packages.  (I found that their Switch Port Monitor worked quite well to watch my SNMP-capable DSL router...)

Moving to the handheld/tablet world, I recommend Fing Network Scanner for iOS.  Fing not only does the basic inventory-by-IP-address, but allows you to name individual devices (useful for identifying newcomers), maintain a history and run complete port scans.  If you're using Wake-on-LAN with any of your devices, Fing can trigger them as well.  It will even do reverse DNS lookups and 'remembers' disconnected devices!  Fing runs on any iPhone, iPod Touch or iPad running iOS 4.0 or later.  I've only had Fing for two weeks or so, and I've already inventoried several networks out of idle curiosity (think local McDonalds and hotel wi-fi...)

Finally, for the truly serious, there's Nmap.  Nmap is, in my estimation, simply the best network scanning software to be had.  It does EVERYTHING, from simple IP inventories to elaborate port scans, OS identification through IP fingerprinting, and penetration testing.  One can even write scripts to drive particular test methodologies.  Nmap is so complete that the original author had to write a book to explain it all.  Best of all, Nmap is open source; its download page includes precompiled distributions for Windows, Mac OS and Linux, with full-blown source code distributions to boot!

You may have noticed that I rarely discuss Android apps; well, I don't own an Android device, so I can't test anything on that platform.  If you have a recommendation for Android, PLEASE share it in the comments!

(UPDATE: In the comments, I learned that Fing is available for Android - thanks, Peter!)

ONE WORD OF CAUTION: You should not use ANY of these tools on networks where such scanning/inventories would be unwelcome!  While many public access networks are fairly lax in their security, most enterprises of any size DO run active intrusion detection systems (IDS), and a far-ranging address/port scan WILL set off their alarms.  You do NOT want to have a meeting with Corporate IT Security folks to explain yourself - trust me on this one.

Having said that, I think that any of these tools will do a fine job of helping the typical "I got Internet at my house" user to better understand exactly what devices are using their network.

PS: If you're curious, here's my home network: 1 desktop PC, 3 iPhones, 4 iPads (3 school-issued), 2 iPods, 1 Blackberry Bold, 1 Blackberry Playbook, 1 Nintendo Wii, 3 Nintendo DS/3DS, 1 Lexmark printer, 1 HP laptop, 2 ThinkPads, 1 IdeaPad, plus my "work kit" of 1 ThinkCentre, 3 ThinkPads and 2 IBM xSeries servers.  Toss in the wireless AP and the DSL router, and that's 29 devices...
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