I'm Ben Miller, a Wi-Fi expert. Ask me anything.

I blog at http://www.sniffwifi.com

I teach Wi-Fi for Global Knowledge. Here is one of the courses I've written and now teach: http://www.globalknowledge.com/training/course.asp?pageid=9&courseid=16300&country=United+States

I am a co-author of the CWAP Study Guide, which prepares people for an advanced Wi-Fi analysis certification: http://www.amazon.com/Certified-Wireless-Analysis-Professional-Official/dp/0470769033

My Twitter is http://twitter.com/ben_sniffwifi

Comments: 1336 • Responses: 70  • Date: 

dannyboylee89 karma

If my wife sees things better when they're further away, does that mean she's farsighted? Also- my wife has three eyes. Explain.

benjamiller65 karma

Is that your way of saying she enjoyed 127 HOURS?

Noxate86 karma

What is the best router on the market?

benjamiller191 karma

I prefer the Apple Airport Extreme, but it is expensive. A good value is a e2500 from Linksys, but if you like DD-WRT firmware use the e2000 instead.

Tentra18 karma

Why do you prefer the e2000 over the e2500 for DD-WRT? I've been running DD-WRT build 21676 on my e2500 and haven't had any problems aside from the lack of my 5GHz antenna functioning, which I understand to be a DD-WRT issue rather than being a router-specific issue.

benjamiller30 karma

You hit the nail on the head. 5 GHz doesn't work well for the e2500. It works fine for me on the e2000.

Euphoric_Doctor51 karma

can you give me a few tips for strengthening internet/wifi security

benjamiller88 karma

At home, longer passwords are more important than capital numbers or non-alphanumeric characters. In the enterprise, enforce mutual authentication if you use static passwords. For guest WiFi, use WPA2 Personal instead of a splash page so that your guests' data is encrypted.

Bat_turd49 karma

What is your day job?

benjamiller61 karma

WLAN pro.

Teaching. Post-install consulting. Little bit of pre-install surveying. Blogging. Writing whitepapers, books & courses.

Bat_turd20 karma

How did you get started in IT? What was your path to this point?

Thanks!

benjamiller25 karma

I got a job with a large consulting firm where I did some IT after graduating from USC (Fight On!), but really it was a friend who got me into wireless and a career in IT. Being able to write well, having a positive attitude towards users and attention to detail are three things that have helped me a lot.

kimota6836 karma

As we are nearing a 5 GHz-heavy future, what do you recommend to avoid over-deploying dual-band APs (and thus oversupplying 2.4 GHz)? Trust a vendor's implementation or....?

benjamiller42 karma

Turn off the 2.4 GHz radios on all but 3-4 of your APs that cover a given location.

benjamiller23 karma

Thank you for the questions, all.

krazykoo20 karma

What is the coolest thing you can do with WiFi most people don't know about?

benjamiller20 karma

Most devices can be used as APs to share broadband wireless (3G/4G) Internet connections. You can also decrypt anyone's wireless traffic as long as you know the WPA2 Personal passphrase.

J-B_Say18 karma

Can you please dispel my dad's belief that google chrome causes our router to crash?

benjamiller16 karma

I cannot. I have had laptops bluescreen because of a wireless router's firmware and it is possible that it could happen in reverse. It is unlikely, however.

J-B_Say10 karma

damn... well can you confirm my (probably irrational) belief that really cold weather, say 0 degrees F, makes it slower?

benjamiller32 karma

It is possible that the wireless router/modem will malfunction at that temp. The low temperature won't affect the radio waves, though.

tenurestudent14 karma

why does my Wi-fi crap out when I run the microwave? It was a big issue living on a sailboat, but it still happens now that we are back in an apartment.

benjamiller18 karma

Microwave ovens use 2.4 GHz radio waves, just like 802.11b/g/n wireless routers. When two devices transmit on the same frequency at the same time in the same place, interference occurs.

You can try a wireless router that uses 5 GHz radio waves (802.11a/n/ac) or get a new microwave oven. Microwave ovens usually emit interference because the shielding has worn out.

pujolsrox1114 karma

is 5 Mbps up/down enough internet for 6 males who play games online?

benjamiller5 karma

I am a WiFi guy more than a broadband or video game guy, so you'd have to ask someone else.

Wellpaidrichguy10 karma

why do my customers call it a rooter?

benjamiller13 karma

They are British.

sunrise_sunset10 karma

What's your opinion on wifi and health? Do you think the signals pose a risk to developing memory loss, brain damage, etc.

benjamiller24 karma

It's a subject I have yet to study, so I'll be speculating here. Wi-Fi signals are so low (most devices require about 0.0000000001 Watt received to have a solid connection) that I have a hard time believing that they are worthy of worrying about health risks.

yuxuibbs10 karma

How do you connect two computers together so that you can control another computer through your own computer that's using the same wifi and is in the same house?

And is there a reason why the school wifi at the public schools are so slow other than there are too many devices using the wifi at the same time?

benjamiller13 karma

First question I'm useless on. I'm a WiFi more than a software guy.

Second question the problem is the RF. It was probably planned haphazardly or an incorrect site survey was done. And in most cases it was done without directional antennas.

herpderpherpderp9 karma

If you link to product, can you please not use amazon links? The embedded affiliate codes qualify as spam links. Thanks!

Alenola9 karma

[deleted]

benjamiller12 karma

Lots of times it's an old or cheap wireless router/modem. Do the signal bars go out? Or does the signal stay up but the Internet access go out?

jpe775 karma

for mine, I think the signal stays. I don't do much heavy internet stuff (just blogs and junk), but I have a cell tower hooked to the modem and every 5 minutes or so there's a hiccup and the cell connection cuts.

could it be the router? (which is both cheap and old......)

benjamiller12 karma

Yes, cheap and old wireless routers do get inconsistent. The cable/phone company will ask you to connect with a wire to test if it is their fault. Try that and if the signal is solid, then the problem is probably your wireless router.

GodofIrony9 karma

when do you think we'll get complete and total wifi coverage across the globe?

benjamiller27 karma

The same day we use the last drop of oil.

tedshuo8 karma

what are the differences between WIFI and WLAN? On Iphone, there is a feature called 'iTunes WLAN Sync',but same feature on Ipad is called 'iTunes Wi-Fi Sync', I am confused.

benjamiller12 karma

WLAN is a technology. The technology of extending a local area network (LAN) wirelessly. WiFi is a product certification for standardized devices. Companies that make WLAN products that are designed to work with other companies' WLAN products may get their products tested by the WiFi Alliance for WiFI certification.

Carvinrawks8 karma

Let's call my wifi signal at work "connection X" and call my 4g cell signal "connection Y."

Why isn't there something in my phone that makes this the case:

When more than one connection is available
If connection Y is stronger than connection X use connection Y
If connection X is stronger than connection Y use connection X

It's maddening. If my wifi signal cuts out, my phone gets stuck trying to load something forever, then eventually decides it can't load the page. WHY NOT JUST USE THE OTHER PERFECTLY FINE SIGNAL?!

This drives me crazy all day.

benjamiller8 karma

Turn the transmit power on your wireless router/modem down to about 25 mW (14 dBm). It could be that your phone can receive just fine but has too low a Tx power to reach back to the AP.

Hellview1528 karma

Is going to school for 1 year (transfer credits to cut off a year) for a Computer Information Systems Associates of Science Degree worth it?

benjamiller15 karma

For some larger companies it is a nice way to get an entry-level, low paying position. In general degrees are of less value in IT, however. I have a friend w/ no college degree who makes well into 6 figures + got lucrative stock options doing what I do and he has no degree past high school.

greglyon8 karma

How does a splash screen authentication work exactly? For example does it capture the MAC address of the connecting device? I am because I'd love to get a chromecast working on hotel wifi, and have so far been unsuccessful.

benjamiller15 karma

Splash page security is based on MAC address, but there may be additional security that blocks MAC address spoofing. Try changing your laptop's MAC address to match the Chromecast's client MAC address (Chromecasts have 2 MAC addresses: 1 AP and 1 client) and see if it can connect after you authenticate your laptop. Alternatively, if you have a Windows laptop, try using hostednetwork to turn your laptop into an AP that the Chromecast can connect to while simultaneously using your laptop as a client for Internet access.

InVivoVeritas5 karma

I was having a lot of issues using my Apple Airport express with my time warner service, and when I installed a cheap D-link router it worked much better. Are these compatibility issues with the airport express and time warner cable?

Also, is it possible to set up a wifi relay so that areas that are behind walls can get wifi from a router on the other side of the wall?

benjamiller9 karma

I agree that the AirPort Express was probably malfunctioning.

To extend coverage behind walls, use a Powerline connection between two wireless routers instead of a repeater.

electronicpersuasion5 karma

Could a powerline work for an outbuilding 200' from the main house powered off a subpanel from the main house? How far apart can these things be?

benjamiller7 karma

Powerline is all about the electrical wiring. I'd say try it and see if the electrical wiring is linked somehow, but I kind of doubt it.

erikturk5 karma

I finished CWNA. Which next SP,DP,AP ? What do you think the minimum of hardware I should have for the next step? A WiSpy for design, a MacBook Pro for analysis.

benjamiller9 karma

CWSP is the most widely known, but I prefer CWAP. I am biased because I co-authored the study guide for CWAP.

For CWAP, an Apple laptop with Wireshark + a partition for Windows + WiSpy is a great place to start. For CWSP, I used trial versions of AirMagnet WiFI Analyzer for the WIDS and an AP with a built in RADIUS server for EAP.

Shadowhawk1094 karma

I've worked on alternate WiFi standards in academia; since the invention of Wireless-G, we've had N (with a focus on dual-antenna) and AC (with a focus on lower-energy/more battery-life).

My focus was more on the power of using RTS/CTS handshakes to help manage network traffic and get all given nodes to cooperate. This was a good 3 years ago.

What do you think the next "big thing" for WiFi will be? What do you think the biggest thing lately has been?

benjamiller3 karma

802.11ac is less about battery life and more about speed and capacity increases.

RTS/CTS is an underused technology, but so many devices lack support for setting RTS thresholds that it has become marginalized.

I think the next big thing is a move away from MIMO. It is such a battery drain. Already tablets and smartphones are made without MIMO. I am expecting a lot of laptops to follow suit.

jar-is-a-door4 karma

My wifi just stopped working on my laptop - I can only get the internet on it when I directly plug it in. The diagnostic trouble-shooting doesn't do anything - are there any steps I can take to get it up and running again?

benjamiller9 karma

WiFi radios on laptops die sometimes. Try to connect your smartphone to your wireless router to ensure that it's not the router. If the router is fine, try the Network Preferences (Apple) or Network Connections (Windows) to make sure your WiFi is enabled. If you have a Windows laptop, this WiFi USB adapter is small, fast and relatively inexpensive: http://www.amazon.com/AE6000-Linksys-Wireless-Mini-Adapter/dp/B00BWT1IFE

jar-is-a-door20 karma

Dear lord, it was just disabled. Thank you. Also, I'm an idiot with these things. Thanks.

benjamiller12 karma

You're welcome. I've done that several times so don't feel bad.

Sit-Rep3 karma

BEN! I was one of the Marines that took your Wifi Class in North Carolina. I remember you! We took it in 2006 or early 2007 if I remember correctly. We gave you tons of shit, but you were a supremely good sport about it.

Reddit: This guy knows what he is talking about.

benjamiller3 karma

Hey hey! I remember that class fondly. Camp LeJeune, was it?

bigbankhank23 karma

What is your favorite tool for measuring CCI? WiSpy? Airmagnet wifi analyzer? What are your tools of choice for measuring the "performance" of the RF? Do you ever find yourself modifying patch antenna's to reduce the back-lobes (in an effort to limit CCI?).

benjamiller2 karma

WildPackets OmniPeek is my favorite for hardcore analysis. AirMagnet WiFi Analyzer is great for field work that requires a quick solution.

ifiwasajedi2 karma

hey what do you think of that study that proved wireless routers stop plant growth and actually cause them to die?

benjamiller2 karma

It sounds like faulty science from an activist organization, but who can say?

benjamiller2 karma

Keep posting questions if you have anything new. I am taking off for now but I will check in periodically. Thank you for all of the questions.

benjamiller2 karma

I just noticed how many unanswered questions I have. I'm going to start skipping long questions and questions that have already been answered. If someone can put together an FAQ, I would appreciate it. Otherwise I'll put one together eventually.

silvrenithron2 karma

Any advice on getting multiple routers to play nice on the same network? I have an airport extreme as my primary and an e2000 and an e3000 as secondaries. My main issue is there's a huge lag with the signal switching over when I walk from the room where the airport signal is strongest into the room where the e3000 signal is strongest. I want to avoid dd-wrt if possible.

benjamiller2 karma

I use Powerline to link up multiple wireless routers. For the wireless router that is near my cable modem, I have it set up like normal. For the other wireless router, I turn off DHCP service and I set the SSID to match. I use different channels on the two wireless routers.

AaronFPS2 karma

Why does torrenting fuck up my 4mbps (50kbps up) connection?

benjamiller3 karma

I am less knowledgable about home Internet connections than about WiFi.

v1no2 karma

I've tried to change my fragmentation length and my RTS threshold of my NETGEAR router at home as there were wierd speed issues occuring on our wireless network.

Everything is better now, as I've returned the values to default (although the NETGAR website has some conflicting information, look at what they recommend and the default values).

Could you explain what these two things are though? I've been curious for ages...

benjamiller2 karma

Fragmentation sets a maximum transmission length for everything that goes through the air. If you set Frag threshold to 300, then a 1500 byte frame would have to be split into 300 byte fragments before it is sent. Positive: fewer collisions. Negative: more overhead from headers and interframe quiet periods. It is designed to help when interference from non-802.11 sources is a problem. I generally avoid it.

RTS/CTS is where two headers (one from the transmitter and one from the receiver) are sent before data is sent. All frames larger than your RTS threshold use RTS/CTS. It is designed to mitigate problems from nearby 802.11 devices causing interference. I have used it on several occasions, but it may cause unnecessary overhead if the channel is relatively clean.

wieschie2 karma

I have a 17 dbi antenna i bought separately for the wireless card in my computer (I understand that the common rating is 3-5).

How well can this really scale reception quality? I'm sure the benefits fall off at some point.

Does adding multiple antennas help on a receiver, or is it more for routers to keep them omnidirectional?

benjamiller2 karma

You should check the beamwidth on that antenna. A higher gain antenna is great if your stations are within the beam.

Usually you want omnidirectional antennas on stations.

thechubbmeister1 karma

Is wifi harmful?

benjamiller1 karma

Answered below.

EDITED: I'm new to Reddit. Just figured out Permalink. Here's the answer: http://www.reddit.com/r/IAmA/comments/1oguh2/im_a_wifi_expert_ask_me_anything/ccrwtoi

GodofIrony1 karma

My laptop connects to my wifi at a functional ( I.E. fast load times) level only when plugged in. This is at my home connection, and doesn't affect other signals that I can connect to.

Any idea why this is?

benjamiller1 karma

If you use a wireless modem from the cable/phone company, try using a separate wireless router. My parents had a similar situation until they complained to TimeWarner. TWC installed a separate wireless router and things improved.

The problem could also be your laptop. Try your laptop away from home to verify that it has good WiFi.

Celti1 karma

I know I'm a little late to the party, but what do you think about the Ubiquiti AirRouter? Is it a solid device or would I have been better off trying the AirPort Extreme even though I don't have a Mac in the house?

benjamiller1 karma

I tend to avoid Ubiquiti. I have less experience with it than with other stuff, but it seems to be designed for hackers.

In my experience the AirPort Extreme works great with Macs and non-Macs. My girlfriend has a HP Windows laptop and I have an Android tablet & a Chromecast that both connect great.

VoRicebowl1 karma

Is it true that the limit on most routers for wi-fi is 20 mbps?

Would it be the router at fault or the wi-fi card?

I called up Verizon and that's what the rep said but I was still unsure.

benjamiller4 karma

The wireless link of wireless routers can go well above 20 Mbps, but you may have to be close and you need one that supports 802.11n or 802.11ac.

booloo221 karma

I live in a big house (fraternity) and we have a regular router/modem but the provider says its super charged, it works great in the rooms by the hardware but gets very poor away from it. Is there anyway we can alter or mess with it to improve signal strength or the distance of the house the internet can cover? We have an extension too but it's also weak.

benjamiller1 karma

Use Powerline and set up at least one other wireless router elsewhere in the house. Turn down the transmit power of your wireless routers so that it is around 25 mW (14 dBm). Then just make sure you have coverage everywhere.

bigpuffy1 karma

WHat does it mean when I'm connected to a router, but in the preferences it says there's no IP address? It happens a lot and doesn't let me connect to the internet until it goes away.

benjamiller1 karma

Most likely you have an inconsistent wireless router or wireless modem. I find that the Apple Airport Extreme is the most consistent consumer-grade wireless router.

Sometimes client/station devices can be inconsistent in getting an IP address, but this is less common.

The_Reddit_Narwhal1 karma

I have a pretty specific question, so if you don't want to answer, don't feel the need. We have a wireless router set up, with a wired speed of 150mb/s, probably around 75mb/s for wireless. The wireless perfectly for every computer in the house except mine, and I'm literally right beside the router. It works for a couple minutes, then slows down to an unworkable crawl. Works perfectly fine wired though. I have also never had a problem with any wirleess anywhere else, just here. Any idea why that's happening, or how to fix it? Thank you!

benjamiller1 karma

It sure sounds like your computer right beside the router has a bad WiFI adapter. Try using a different adapter, like this USB adapter that I recently bought: http://www.amazon.com/AE6000-Linksys-Wireless-Mini-Adapter/dp/B00BWT1IFE

anon0man1 karma

Why are WiFi signals so biased to short range use? They have gotten a little better over the years but essentially they only work within 100ft and not through to many walls. We can receive pictures from space sent from a craft sent out in the 70's. Its location is "on the edge of the universe." We have data signals used in cell phones that travel to cell phone towers but WifFi is only 100ft. at best. Why do you think this is? I believe they have the technology to make your WiFi signal as long as you want to set it for but don't. What technology or conspiracy's are holding the WiFi signals to 100ft. I would like to get WiFi in my garage without running cables.

benjamiller1 karma

Wi-Fi uses unlicensed frequency channels. That means that anyone can use the same frequency without a license from the FCC (or whatever regulatory org oversees RF in countries outside the USA). If the distance were allowed to be greater it would cause too much interference in those unlicensed frequency bands.

storko1 karma

Where did you do your doctorate?

benjamiller1 karma

I've never met a Wi-Fi Expert with a doctorate and I doubt I ever will.

MAINO1 karma

is it possible to check someone website visit using wi-fi hack?

benjamiller2 karma

If the person is using WiFi that is not encrypted with a VPN or WPA/WP2, then yes.

MAINO1 karma

how do i know my own wifi is encrypted?

benjamiller2 karma

If you're using a Mac, hold down the Alt/Option key when you click the WiFi signal. If you see WPA or WPA2 you're encrypted. In Windows you'll see a yellow notification if the network is unencrypted. On iOS go to Settings -> WiFi and look for a lock symbol by your network.

Alerion_1 karma

Why does my connection almost always drop within seconds or minutes of starting any sort of download or YT video? Is it the router that can't handle the sudden increase in demand?

benjamiller1 karma

If the signal bars are staying full, then it is probably your cable or phone company. Maybe you need a new wireless modem or maybe the line is bad. If the signal bars go out, then it is your wireless router. I find the Apple Airport Extreme, while expensive, is the most reliable of the consumer-grade wireless routers.

MNDave1 karma

How can I take a signal from an Alfa AWUSO36H (Realtek RTL8187 chipset)and broadcast around my home? I have an Alfa R36 but it seems to eat up so much of the signal that I gave up on it.

benjamiller1 karma

I recommend avoiding repeaters. Powerline adapters work so much better at home. Just get a second wireless router and place it in a different part of your home attached to the other end of the Powerline conenction.

LeagueofEnts1 karma

How can I increase the range of the wifi in my house, my router is on the other side of the house from my game room and the signal is super weak

benjamiller1 karma

Use Powerline and get a second wireless router for the other part of the house.

spearhard1 karma

Is there any truth to the notion that WiFi is dangerous or harmful in some ways? There's a guy at my university who is terrified of WiFi and basically turned his dorm room into a Faraday cage by lining it with alumnium foil, and he apparently sleeps with a Faraday cage around his bed too. He also goes around unplugging routers, and once rented a ZipCar so he could sleep in the parking garage where there was no WiFi.

Obviously, this kid is an extreme case, but is there any evidence that continued exposure to WiFi has health effects?