Sniff Wi-Fi

A common conundrum for enterprise WLAN administrators is guest access. You often want or need to provide it, but you want to make sure the guest WiFi has a minimal effect on the internal network. One way that people try to limit guest access is by specifying low speeds, but that is a bad idea that usually causes the internal WiFi to be worse off than it should be. I was doing some work at a hotel in the Chicagoland area recently when I came upon another example of bad guest WiFi. Bad guest WiFi is quite common, but this one was avoidable. I've seen bad guest WiFi because of under-covered areas and because of over-covered areas. I've seen some guest WLANs with  over-saturation of stations and others with under-saturation of broadband. As with any WiFi design, there is a little bit of art in the science. You have to look at numbers like signal-to-noise ratio and users-per-channel but in the spaces where desired numbers collide, the owner of the WLAN has to make good choices ...

In life, the opposite side of intellectualism is sometimes a good place to be. Analyzing a WLAN is not one of those times. When someone tells you that a boring movie is great because it was shot well or that a nil-nil draw in football (world, not American) was thrilling because of all the close chances, the best idea is often to sit back, draw a creamy bowl of vanilla ice cream and tell that nerd that you don't need a P.H.D. to know what makes you happy. This type of anti-intellectualism is almost certainly born as a rebellion against deep analysis (perhaps making the rest of this blog post intrinsically ironic). Sometimes, though, deep analysis is needed to prevent festering problems from bubbling over at bad times. It takes no great insight to point out that there is a penalty to eschewing analysis. The man who  avoids Oscar-bait movies may miss a work of great emotional power. Disregarding scoreless football matches would have caused fans to miss the most thrilling match of th...

I love free stuff. I love it even more when it works. And while I am a natural skeptic of the usefulness of free software (thus contradicting a timeless programmer's joke ), the ability to run KisMAC-ng with an AirPort Extreme interface in Monitor mode is quite nice. Not as nice as it could be if a few little tweaks were made to the software, but for a free product it remains the best WiFi sniffer for Mac OS X. Way back in January of this year (seems further back than that, which is interesting since years are supposed to feel faster as you get older, right?) I wrote about using a combination of KisMAC, Wireshark and a DWL-122 802.11b/g USB adapter to do WiFi sniffing when running Mac OS X . Six months later I wrote about sniffing with a Mac again , this time focusing on using a virtual machine. The basic gist of those updates was that running Windows on your Mac is the best way to sniff, but if you must run OS X then you can at least capture 802.11 b/g frames if you have a DWL...

The Internet wireless community was set aflutter last week when Eric Butler , a freelance developer from Seattle, introduced Firesheep , a Firefox extension that is advertised as a way to perform sidejacking attacks over unencrypted wireless networks. The software is super slick and all, but what interests me is the way it handles frame capture.  For those who may have missed it, Firesheep is a Firefox extension that allows users to view web sessions that are active on the channel. It works via a wired or wireless channel, but the prospect for wireless viewing received much more press because, A) nobody uses hubs anymore, and B) wireless vulnerabilities always get much more press. The tool is slick and, as far as I can tell, a better name for it would be, "Screw Facebook". From the unscientific tests I've done, Firesheep users are able to gain limited access to other people's accounts on a number of popular sites, but the real eye opener is the ability to view an...

A Twitter follower asked a while back if I could use the blog to give some tips on using WildPackets OmniPeek. Seeing as how I'm always in need of interesting stuff to write about, I figured I'd give it a shot. Here, then, is a quick look at how to analyze station performance in OmniPeek. There are a lot of metrics that can be used to analyze a station's performance. You might look at whether the station is using high or low rates. You could look at how much channel bandwidth the station is consuming. You should look at how many retransmitted frames are being sent and received by the station. All of these different ways to analyze a station's performance have one thing in common: you have to configure a filter on your sniffer that captures only your station's traffic. The first step of creating such a filter in OmniPeek is to find out what channel your station is on. Start out by finding out your station's MAC address (for my laptop, it's 00:1f:5b:cc:3b...

The CWNP Program gave their CWSP (certified wireless security professional) exam a refresh earlier this year, and I finally got a chance to take the test a while back. I found it to be a good exam that requires deep knowledge of the 802.11i amendment. The CWSP certification is one of three professional level certifications from the CWNP Program. CWNP's professional level certifications require the candidate to pass the CWNA (certified wireless network administrator) exam along with a professional level exam. The three professional level exams are CWSP, CWAP (analysis) 1 and CWDP (design). Currently only the CWSP exam is available, with the other two exams scheduled to be available later this year or early next year. This is the fourth version of the CWSP exam , and in my opinion it is in line with versions two and three of the exam. If I had to give exact ratings, it would be the best of the four versions by a narrow margin over version two.  It is almost unfair to com...

I dislike Google. It may be unfashionable, it may betray my corporatism and it may be ironic (especially considering that I'm taking advantage of Google's wonderful Blogspot tools at the very moment), but it's true. I dislike their faux-openness and I dislike their bullying of old, unfashionable companies and I dislike their disingenuous approach to lobbying. That's why it's so hard for me to write this: Google is a victim. People are trashing them over their capturing of data while sniffing WiFi networks and they deserve better.   Attacking Google has become what praising Google was back in 2007: the fashionable thing to do. People dislike their position on wireless Net Neutrality, their search rankings and, yes, their WiFi sniffing habits. For me, it's been quite the reversal. I began disliking Google because of their support for Net Neutrality and the so-called "open" requirements for the 2007 wireless spectrum auctions. That put me at odds with...