Sniff Wi-Fi

Eleven months ago, I wrote about Fluke Networks' Ethernet testing tool, the LinkSprinter .  Now there's a new model, the LinkSprinter 300 , and Fluke was nice enough to send me one to test.   LinkSprinter 300 is basically the same as the LinkSprinter 200, except it costs an extra $100 and it has two extra features: one cool and one that I haven't tested. I really, really hate it when people say "read this" in the middle of a discussion.  It is sauce of the weakest variety.  Just frickin' summarize it.  People tend to give me the ol' "read this" either when discussing a topic that they've written about or in an attempt to cite evidence.  In both cases, a summary will do.  If you are discussing Wi-Fi sniffing with me on Twitter and you wrote a white paper saying that Wireshark is the bee's knees, then tell me why on Twitter.  If you believe that it wasn't a fact that the Earth is round until Greek philosophers proved it a few th...

I wrote about using Discovery software , and then it dawned on me: many people prefer pictures. Here, then, is how I use Discovery software when troubleshooting Wi-Fi, illustrated. First, I figure out which device needs troubleshooting.  In this case, let's pretend it's one or more iPhones. (That #nofilter picture was taken by me at about 4:50 a.m. on the morning of January 20, 2009.  It was COLD a.f. out there.) Notice how my iPhone shows RSSI instead of signal bars.   Your iPhone/iPod/iPad can , too. Once I know which device needs troubleshooting (and, PLEASE, do not skip that first step.  Troubleshooting without using the actual device that needs to use the Wi-Fi is a big waste of time that annoys users), then I need some Discovery software. iOS: Airport Utility (Apple) Mac OS X: Wireless Diagnostics (Apple), WiFi Explorer (Adrian Granados - $15) Windows: Acrylic WiFi (Tarlogic), inSSIDer (Metageek - $20) Android: WiFi Analyzer ( farpr...

Who wants some free stuffffffff?!? You're reading a free blog, so I'm guessing the answer is, "all of us".  And that's good.  You've come to the right place.  Because the first part of my three-part series on Essential Wi-Fi Troubleshooting Tools is going to be about the free (or, very inexpensive) one: Discovery Software. Discovery software, which is also called Scanner software, is software that records and displays information that a Wi-Fi radio gathers during 802.11 Discovery.  There are two ways that 802.11 Discovery can be done: Active Scanning and Passive Scanning.  (Hence, the term "Scanner" software.)  Passive Scanning involves a device listening for Beacon frames that have been sent by APs.  Active Scanning involves a device sending Probe Request messages as a broadcast in the hopes of getting APs to respond with Probe Response messages.  Beacon frames and Probe Response frames carry essentially the same thing: information about th...

Clickbaitttttttttt! "Three Essential Tools"...  Brilliant!  Years ago, I would've been embarrassed to have such a click-baity headline.  No longer. Why the change, you ask?  I don't know.  It could be that I'm in the Money stage of my career.  (You see, I relate most things in life to pro wrestling.  A pro wrestler's career has three stages: Titles, Money and Legacy.  When you're young and you don't know any better, you want titles.  Being " Intercontinental Champion " [or, in the case of an IT guy, " Network Administrator "] fulfills you.  Management takes advantage of that by underpaying people who are in the Titles stage.  Once someone reaches the Money stage, they are no longer impressed by titles.  "You want to make me Intercontinental Champion?  Great.  What's my paycheck?"  The final stage is the Legacy stage, which most of us never reach.   The Rock is in the Legacy stage.  He has won titl...

If there's one recent change in the Wi-Fi world that has brought some heat and light to your humble blogger's cold, dark heart, it's the awareness of device differences.  But there's a difference between understanding that Wi-Fi devices have differences and creating an infrastructure that supports them.  And an important step in setting up a good Wi-Fi infrastructure is finding out whether the APs' transmit power is too high, too low or juuuuuuust right.  It has long been the recommended to have matching transmit power for devices engaging in two-way wireless communication, but with Wi-Fi that rule is often broken.  Breaking the rule is understandable because Wi-Fi environments are often vendor-neutral.  Most Wi-Fi deployments are not like the beaches of Normandy, where everyone had the same model of radio. Sometimes we need really, really good Wi-Fi, and matching the transmit power levels of APs and stations can go a long way towards fulfilling that need....

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There is a dirty little secret in the world of enterprise Wi-Fi: auto-channel selection doesn't work very well.  Every wireless LAN vendor has it.  Every wireless LAN vendor promotes it.  But when the Wi-Fi gets busy or crowded of full of mobile devices, auto channels will leave users frustrated and admins confused.   What to do about enterprise auto-channel?  Why, fix it, of course.  Here are some tips for getting it fixed the right way. First, the positive side of auto-channel: it saves you time.  Auto-channel selection is one of the two primary parts of auto-RF protocols that are supported by enterprise controllers, APs and management systems.  (The other part is auto-transmit power.)  Auto-RF protocols automatically adjust channel numbers and transmit power levels on APs.  Auto-RF protocols use information received by a large number of APs to decide when to adjust.  What that means is that if an AP senses a microwave oven b...