Tag Archives: wifi

The Rule of 10s and 3s

A while back I wrote a blog post explaining how an antenna works when it is connected to a wireless access point. Today I’m going to add to that lesson by explaining The Rule of 10s and 3s. Essentially, you can use this rule to figure out what your transmit power is going to be when you add various connectors, cables, and external antennas to your access points. Without further ado:

Please remember that using The Rule of 10s and 3s does not give you exact figures. It should only be used to perform rough calculations. Also, this video is not intended to be a technical deep-dive into the field of RF mathematics. Instead, my goal is to explain the basics of a complex topic so that almost anyone can understand it. (I’ve assumed knowledge of milliwatts and decibels though).

Dan C.

Bonus marks if you can explain why having this knowledge is important for anyone working with WLANs. Leave your answer in the comments section and share this video with anyone you think might benefit from knowing this rule.

Thoughts After Passing the CWSP PW0-204 Exam

After putting it off until the very last moment, I finally wrote and passed the Certified Wireless Security Professional (CWSP) PW0-204 exam. This was important since it had been almost 3 years since I passed the CWSP (PW0-200) exam and my credentials were set to expire on the 25th of June. Crisis averted! With the exam out of the way, I thought it would be worthwhile to share some thoughts on my experiences while preparing for it.

In no specific order, here are a few things I found very interesting about my time studying for PW0-204: 

  1. Wireless security was much less complicated 3 years ago. When I took the PW0-200 exam, I didn’t have to know anything about 802.11n, 802.11k, 802.11w, or 802.11r. All of these, now ratified, IEEE standard amendments come with their own set of additional security settings and concerns that must be taken into consideration when securing a WLAN. Continuing to educate yourself and staying on top of the latest industry developments is the easiest way to ensure that a certification’s body of knowledge doesn’t leave you behind.
  2. Experience in the field helps immensely with this exam. When I first wrote the PW0-200 exam, 3 years ago, I had a great interest in the subject but very little real-world WLAN experience. This time around, after living and breathing WLANs for 3 years, I found I was able to quickly skim or review a lot of the CWSP Study Guide since I deal with 802.1X/EAP, PKI, and WIDS/WIPS solutions quite frequently in my role as a security consultant. In my opinion, the CWSP certification is a great example of an exam that goes beyond ‘textbook studying’ and really tries to incorporate lessons that can only truly be learned through hands-on experience. Certifications like that rock because they signify practical/useful knowledge instead of just the ability to memorize answers for a test.
Next Step

Keeping my existing CWNA and CWSP credentials was just stop number one on this journey. With that out of the way, I’m now beginning my assault on the Certified Wireless Network Expert (CWNE) designation. Last time I check there were less than 100 CWNEs globally so it’s definitely going to be a challenge. I have to pass both the CWDP and CWAP exams first. Wish me luck and I look forward to posting my thoughts and insights on my next exam this summer.

Dan C.


NCI’s @SimplyWifi Attending Wireless Field Day 2

The time has come. Today, one of NCI’s own will head to San Jose to attend the Wi-Fi Mobility Symposium and then be a delegate at Wireless Field Day 2!

This promises to be an amazing event and we are thrilled to have one of our own attending. Just look at the schedule:

Wednesday, January 25 – Wi-Fi Mobility Symposium

This event will cover important topics such as: Mobile Devices & BYOD, Gigabit Wi-Fi, and Hotspot 2.0.

Thursday, January 26 to Friday, January 27 – Wireless Field Day 2

Two days of in-depth, technical presentations and discussions with many of the wireless industries most exciting vendors (in order of presentations): Aerohive, MetaGeek, Ekahua, Meraki, Aruba Networks, HP, and Ruckus Wireless.

This even will also be streamed live (see display below):

NCI looks forward to sharing all that we learn from this event with our current and future clients. Wireless networking is set to really explode in 2012 and we are proud to be right in the middle of it!

The NCI Blogging Robot


WPS Brute Force follow-up information

On January 1st we posted a little bit of information regarding the Wi-Fi Protected Setup (WPS) brute force vulnerability. As a follow-up, I have performed a bit more research and analysis on the vulnerability and the attack tools. Here is a list of resources you might want to check out for more information: 

No Strings Attached Podcast 

I was privileged enough to participate in the @NSAShow’s episode 2 podcast: Wi-Fi Protected Setup, Battered or Broken? I highly recommend giving the podcast a listen as it contains a lot of good information. I’d also like to thank the host @revolutionwifi and the other guest @matthewsgast for a fun and insightful 45 minutes. 

Simply Wi-Fi 

We’ve already shared my video demonstration of how a WPS brute force attack works. Since then, I’ve created another video, seen below, demonstrating the use of a tool that identifies vulnerable wireless routers. I’ve also taken some frame captures of an attack and provided an explanation of the frames at different stages of the attack. Sample frames have also been made available for anyone who wants to take a closer look in Wireshark.


United States Computer Response Team (US-Cert) 

Here is the original vulnerability note created on December 27, 2011. It details the basic purpose of WPS and describes the vulnerability. 

Dan C.

If you are aware of any additional resources, please share them in the comments section below.

WPS Brute Force Concerns and Solution

Recently, a white paper was written by Stefan Viehböck which documented a few implentation weaknesses in the Wi-Fi Alliance’s Wi-Fi Protected Setup (WPS). Immediately following the release of the whitepaper, a new tool (called Reaver) was released publicly that could be used to brute force the WPS PIN, and therefore, gain access to the WPA/WPA2 pre-shard key (PSK). The attack takes 4-10 hours on average and has an extremely high success rate.

What does this mean for you?

If you are a home user with a relatively new wireless router, you are probably susceptible to this attack. Basically, if your wireless router is WPS-capable you should assume you are vulnerable.

How do you defend against this attack?

The solution is quite simple: disable WPS on your wireless router. This renders the attack useless and it becomes a non-issue for you.

Hey, wait a minute. How come you only mentioned home users?

WPS is a system designed specifically for non-technical people. It is widely implemented in SOHO wireless routers but is generally not an enterprise wireless feature. If you happen to be running SOHO gear in the enterprise, then you will need to see if you are vulnerable as well.

Just how easy is it to perform the attack?

Easy. Here is a quick video demonstration showing how the attack works, and how to protect against it. This video was created using freely, and readily available how-to documentation on the reaver code page.

The Bottom Line

If you are running enterprise gear, you probably have nothing to worry about. If you are running SOHO gear, then you need to look into this a bit further. Increasing the length and complexity of your PSK does not protect against this attack. You need to disable WPS until the protocol can be strengthened.

Oh yeah, and Happy New Year!

The NCI Blogging Robot

Questions? Concerns? Comments? Get it in touch with us below.


Wireless Field Day 2

I was originally going to post this in January, but I just couldn’t wait any longer. From January 25th to 27th, I will be a delegate at Wireless Field Day 2 (WFD2) in San Jose, CA.

My day job focuses primarily on Aruba Networks and Meraki, but I have always made an effort to keep up-to-speed with what everyone else is doing in the wireless industry. WFD2 will be a tremendous opportunity to do so. Sponsoring vendors include:

If the opportunity to get all these vendors in the same room and have a pointed, no-BS discussion about wireless technology wasn’t enough, there’s more! Along with the vendors, there will also be a list of delegates that is nothing short amazing! So far, delegates include:

That’s a lot of wireless knowledge to cram into a single room. Seriously, my Wi-Q will increase just by hanging out with these people for a few days – awesome!

I’ll be tweeting and blogging during the entire event to help make sure that everyone gets to benefit from this amazing event. If you’re interested, you can also check out the official WFD2 channels.

Dan C.

Be sure to check back for more news on WFD2 as we get closer to the event date.

Falsely Accused: The Wireless Controller Story

Every day, innocent wireless controllers are framed for crimes they didn’t commit. This is the story of how one WLAN controller was falsely accused of connection murder…

The Crime Scene – WLAN Connection Murder

Testimony: A user is having difficulty connecting his brand new laptop to the lab WLAN using WPA2-PSK. He has been able to connect to the corporate WLAN but all attempts at the connecting to the lab have failed. Also, the user has been able to connect to other WPA2-PSK protected networks in the past.

Prime Suspect: Bystanders report seeing a WLAN Controller fleeing the scene.

Investigation performed by Detective @SimplyWifi

Are other clients having a similar issue? – No.

Are there comments in the controller’s release notes regarding this issue? – No.

Had client submit to a connectivity test and sent logs to the lab for analysis. Lab results below:

Deauth from sta: 24:77:03:xx:yy:zz: AP xxx.yyy.yyy.zzz-00:24:6c:aa:bb:cc-NameChanged-AP Reason Unspecified Failure

Offender Profile

Based on the resulting debug lab results, it was determined that the wireless client was successfully connecting. However, it would immediately disconnect itself due to an: ‘Unspecified Failure’. The important take-away was, the controller was not initiating the disconnect; it was the client deciding to disconnect. This information allowed the detective to provide the following offender profile:

Age: Less than 1 month old.

Height: ~1 ft.

Build: Standard corporate image.

Behavioural Patterns: The offender is highly mobile but tends to spend a lot of time resting on a docking station on a desk. When connected to the docking station, the offender will likely be physically connected to the wired network via an Ethernet cable.

The Takedown

The offender was located and, as predicted, it was found connected to a docking station. Upon removal from the docking station, the client was able to successfully connect to all corporate and lab WLANs. Detective @SimplyWifi told reporters: “This is another tragic case of the victim turning out to be our perp. Once we started looking at the evidence, it was clear that the WLAN controller was being falsely accused. After that, it was a simple matter of following the evidence back to the victim.”

Final Comments:

In this case, it turned out that an application on the client was blocking the ability to connect to both a wired and wireless network at the same time. As is usually the case, the issue was a client-side issue and required no controller changes to resolve the issue. It serves as a great reminder of the importance of performing detailed victimology in any wireless investigation.

Dan C.

Do you have a story about spending time troubleshooting the WLAN controller only to eventually determine that the issue was with the client? If so, we’d love to hear it in the comments section. Also, if you are having troubles resolving issues on your own WLAN, please contact us and we’d be happy to assist.

DHCP Fingerprinting with ArubaOS

If you’ve read any of my previous blog posts, you have probably noticed that I make an effort to confine my posts to vendor-neutral topics. However, every now and then I come across vendor-specific technology implementations that are so cool that I just have to say something about them. In this case, it is DHCP fingerprinting by Aruba Networks.

Without getting into too much technical detail, this technology watches the DHCP requests of wireless clients and identifies the operating system based on the way each device asks for an address. This feature is really cool because it means you can allow a user to connect to the same ESSID (read: wireless network), using the same username/password, with a variety of different devices, and get different levels of access depending on the specific device type. For example, if the user connects to the WLAN with a company issued laptop then they get access to the internal network. However, if they connect using an iPad they get Internet access only. Didn’t I say this was cool?

Enough typing, I recorded a little demonstration of DHCP fingerprinting for your viewing enjoyment:

As BYOD becomes more prevalent, I think we are going to start seeing technologies like this popping up all over the place. This is a good thing since it gives administrators the ability to allow BYODs onto the network without having to give up on security and control.

Dan C.

How do you deal with BYODs in your environment? If you have thoughts or comments regarding the proper way of dealing with BYODs please share them in the comments section. Also, as usual, please share this post with others if you found it useful or interesting.

A Universal Wifi User Experience Index (UWUX Index)

Back in August I posted my thoughts on some different ways to measure the success of a WLAN deployment. My main argument was that we needed to start finding ways to measure the overall user experience (UX) in addition to all the speeds and feeds. To my delight, my thoughts were generally well received in the wireless industry and the overall consensus was that UX should be one of the primary concerns when designing a WLAN. With that in mind, I think it is time to take this to the next level and try to come up with a standard way of measuring and communicating the UX of a WLAN; I call it the Universal Wireless User Experience Index (UWUX).

To highlight the potential value of this type of index, begin by asking yourself the following two questions. If you answer yes to either of them, then having a UWUX could have helped you.

  1. Consultants: Have you ever tried to talk a client out of certain WLAN UX design choices but failed because you couldn’t find a way to communicate just how user-unfriendly their WLAN was going to turn out?
  2. Administrators: Have you ever been forced to go back and redesign the way your end users register, sign-in, authenticate, and gain authorization to your WLAN after it has already been deployed? Was it, by chance, because the users complained that the WLAN was just too hard or complicated to use?

As I stated above, having a standard way of scoring the UX of WLAN and showing how it compares to other networks could be a very valuable tool when it comes to design and deploying an end product that will live or die by the opinions and comments of the end users. Imagine being able to demonstrate how requiring proxy settings changes on an uncontrolled guest WLAN will lower the UWUX score below a certain threshold; resulting in a dramatic increase in helpdesk requests. The results could be shown in a numerical format and a graphical scale formatso that anyone could understand regardless of technical knowledge.

The benefits of the UWUX Index increase dramatically as more people adopt it. It’s a lot like IQ scoring since no single score has any real meaning. Only when we compare a score to the rest of the scores in the index are we able to start deriving meaning. It’s because of this that I’ve decided to share my plans with the community in the hopes that there will be others who want to help design a universal index that can be used by all WLAN professionals and administrators regardless of company affiliation.

Will it be a challenge to come up with repeatable measurements? Yes.

Will it be hard to create an index that serves everyone’s needs? Yes, but the goal is to have an index that serves most common needs instead of all needs.

Will the end result be incredibly useful? Time will tell but I think the answer is yes. In my opinion, if the end result is that we all focus more on designing for user and business needs, then it is well worth it.

More to come…

Dan C. (@SimplyWifi)

If you would like to contribute ideas on what the UWUX Index should include please feel free to leave a comment below, DM me, or contact me through our website. I already have some ideas but am in the very early brainstorming stages so all ideas will be considered. Also, if you think this could fly, please retweet or share the post with WLAN, UX designers, or end-users so that we can gather ideas from as many different viewpoints as possible.

Wireless Hacking with Fruit

A while back I delivered a short wireless security presentation, at a Toastmasters meeting, designed to explain a technical subject to a non-technical audience. The presentation went well enough that I’ve decided to record a modified version to place here.

This video is a very high-level explanation of how wireless networks operate. This is by design as I want to keep the information accessible to everyone and not just to those individuals who already have a deep technical understanding of wireless networking and information security.

Dan C.

Do you have additional tips for protecting yourself from this type of wireless attack? Leave your tip in the comments section and, as always, please be sure to share this post with anybody you think would benefit from viewing it.