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Get answersto your

Wi-Fi questions

an

Networking eBook

ContentsGet Answers to Your Wi-Fi Questions

This content was adapted from Internet.coms Wi-Fi Planet Web site. Aaron Weiss is a freelance writer, book author, and Wi-Fi enthusiast based in upstate New York. You can follow his monthly Ask the Wi-Fi Guru column, and submit your own question at http://www.wi-fiplanet.com/tutorials/article.php/3809101.

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2 5

Range Extension

Coverage

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8 11

Connections & Signal Boosting

DD-WRT

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13

13

Mac/iPhone

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Get Answers to Your Wi-Fi Questions, an Internet.com Network eBook. 2009, WebMediaBrands Inc.

Get Answers to Your Wi-Fi Questions

Range ExtensionBy Aaron Weiss

Q

: I wish to extend the range and performance of my laptop wireless card when used from my sailboat. I have a Wi-Fi antenna installed on the masthead with a coax terminated with a mini UHF connector. It seems that repeating a WLAN signal is what I need to do, as Im trying to improve performance to Wireless Access Points available at many ports and anchorages. Can you recommend a good technology to use between my external antenna and my laptop PC to accomplish this? -- Cpt Monty A: Wireless networking on the high seas gives a whole new meaning to computer pirates. The good news is that if your sailboat were commandeered by rogues, and if one of those rogues was the helpful kind who isnt looking for trouble, but instead looking for trouble to solve, he would answer your question with an enthusiastic Yar! A wireless repeater is exactly what you can use in this situation, and you can do so quite cheaply using the free firmware DD-WRT loaded onto a compatible router such as the Linksys WRT54G series. You will probably need an adapter to mate your mini-UHF connector with the antenna jack of a router. The WRT54G routers use an RP-TNC connector, but DD-WRT supports a wide range of routers, some of which may use other types of

jacks. I havent found a direct mini-UHF-to-RP-TNC adapter, so you might need to string together a couple of adapters, or buy a short length of custom cable with the appropriate connectors at each end. Do be sure that a router you choose has detachable antennas. Once setup, you can access the routers administration interface from your laptop. In DD-WRT you can configure advanced wireless settings to direct the router to use your external antenna for sending (TX) and receiving (RX). Using the routers interface you launch a scan for available networking using the fabulous visualization tool called WiViz, built in to DD-WRT, which will display a real-time radar view of access points within range of your boat. When you configure DD-WRT as a repeater, you will define a virtual wireless network (SSID) that will be re-broadcast on your boat, which you can connect to wirelessly from your laptop. Ahoy! (Big aside: If for some reason you cannot get DD-WRT repeater mode to work to your liking, the second and slightly more complicated solution is to build your own repeater using two routers, with one running DD-WRT in client bridge mode. As in the first scenario, you will connect your mast antenna to the DD-WRT router and use it to scan for and associate with an available network.

When you configure DD-WRT as a repeater, you will define a virtual wireless network (SSID) that will be re-broadcast on your boat, which you can connect to wirelessly from your laptop. Ahoy!2

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But instead of trying to configure DD-WRT to also repeat the signal, you would use an Ethernet cable to connect a LAN port on the DD-WRT router to the WAN port on a second wireless router of any make. This second wireless router would then see your DD-WRT router as a broadband connection, and broadcast it on your boat just like any DSL or cable connection.) Q: Hello! I have a question concerning connecting multiple routers with different wireless modes. I would like to create the following: Router0actsasanAPandis connected to the Internet. Router1(LinksysWRT54G/GL/ GS,DD-WRTv24(05/24/08) std)actsasarepeaterfor Router0(AP)&isconnectedto Router2withWDS. Router2isconnectedtoRouter1viaWDS. IsthispossibletosetupinDDWRTv24?-Josh

Router1: WDS with MAC address of Router0 and Router2. Router2: WDS with MAC address of Router1. Keep in mind that each wireless link halves the available bandwidth, so wireless clients connected to Router2 would max out at 25% of LAN bandwidth when exchanging data with clients connected to Router1. If for some reason you simply had to preserve your mixedmode arrangement, you could add a fourth router (Router1a), connected by wire to Router1. Configure Router1 as a repeater for Router0 (as it is now) and Router1a as a WDS node linked to Router2. You might do this if, for example, Router0 does not support WDSbut then, if youre buying a new router, why not simply replace Router0 with one that does support WDS? Q: I am grappling with the concept of the Wi-Fi booster. For example theHawkingHSB2isanRFsignal amplification device with many fans boasting magical improvements--but how? Its surely easy enough to boost output power and thus be seen as a stronger signalfromfartheraway.But the device comes with a paltry 2dbiantenna,leavingusallwith the cosmic mystery of how the return signal becomes suddenly adequate. I suppose that the receiver within the booster could be extra adept at rooting around in the tall grass to extract signal, but if there is thatmuchSNRleftover,whyarentthequalitycomponentmanufacturersexploitingitalready?Ron A: Although my expertise in RF is limited, I am inclined to agree with the sentiment in Rons first paragraph. These so-called Wi-Fi boosters are basically amplifiers that make the transmitted signal louder (if you think about it in radio terms). But unlike a radio, the client is not a passive receiverit, too, sends signal back to the wireless transmitter. The client is limited by the power output of its own transmissions. In other words, the Wi-Fi booster may let your client hear the wireless router from a further distance than it would otherwise, but the client itself might not be strong enough to send anything backleaving you in the same boat as if you couldnt see the wireless network at all. Or more specifically,

A: What you describe sounds very much like a mixed-mode daisy chain. If that sounds like a fancy technical term, its notI just made it up. But this is theoretically a daisy chain configurationrouter0 connects to router1 connects to router2. But youre using two different kinds of relays for each link in the chainDD-WRT repeater mode in link 1 and WDS (wireless distribution system) in link 2. Such a setup would require that your middle router (router1) act as both a wireless repeater client and a WDS node. I dont think this is possible. Configuring your router as a WDS node is one state of being; configuring it as a repeater client is a different state of being. As far as I know, it cannot be in both states at the same time.

Many users have reported that, when cranked to max output, these Wi-Fi boosters can actually hinder performance of nearby clients, whose own receivers essentially drown in the noise

The first question that comes to mind iswhy mix modes? Why not configure WDS on all three routers? You can chain via WDS and maintain the same physical relationships. Your WDS configuration would look like this: Router0: WDS with MAC address of Router1.

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dangling an SSID that you can see, but not associate with. Also remember that when you amplify signal you also amplify noise. Many users have reported that, when cranked to max output, these Wi-Fi boosters can actually hinder performance of nearby clients, whose own receivers essentially drown in the noise. To minimize this problem, one may need to compromise by setting the Wi-Fi booster to a midrange power levelsay, 100 to 200 milliwatts. Of course, this will also reduce its maximum range, and so whats the point? The point, according to those who have evaluated these boosters, is to better fill in your existing wireless range. In other words, if you expect the booster to give you a strong signal much further away than you could before, this may not pan out. But, if you would like to give a boost within the range you already experienceand maybe catch some of the dark corners that are otherwise too weaka signal booster set to a mid-range power output could very well do the trick.

enough. Using repeaters in this scenario might not be the best solution. For one, each repeater will reduce your network bandwidth. Two, assuming these houses are outdoors and not inside a glass bubble like in the underwhelming Simpsons Movie, the span between them is outside, and installing networking gear outside adds an extra level of complexity (power, weatherproofing, and thieves, for example). You will want to use directional antennas connected to wireless routers in each house. It sounds like you have a reasonable line of sight between housesa few scattered trees should not be a big problem; a forest, or a steel wall, might be more significant. It sounds like the Internet connection is at your fathers house (hopefully he pays for it, too). You want one wireless router there, with an external directional antenna. This means you need to choose a router with a detachable antenna so you can connect a replacement. In your house, you want to

An entirely different way of using a Wi-Fi booster would be for creating a long-range fixed wireless link. In this case, you dont care so much about clients near the receiver, so you can pump up the power output.

An entirely different way of using a Wi-Fi booster would be for creating a long-range fixed wireless link. In this case, you dont care so much about clients near the receiver, so you can pump up the power output. Plus, you would want to use a pair of boosters, one at each end of the link, so you dont wind up with the asymmetrical power problem described above. Finally, you would also want to replace the paltry 2dbi antenna with a more powerful directional antenna. Youll always get the longest range using directional antennas precisely aimed at one another, but of course this will not provide much or any signal outside their straight-line path. Q: I have a big problem. I need to share an Internet connectionwithmyfather,butwelive600feetawayfrom one another, and we have a few trees in our sight line. Itriedafewnewrouters,buttheyonlygolike200feet. Doyouhaveanysuggestions?Willanyrepeatershelp... could I use two repeaters or three? Unsigned A: Six hundred feet is indeed a far distance in wireless networking speak, although if this were a personal relationship column, 600 feet from a parent might not be nearly far 4

use a wireless router that can be configured as a wireless client. The easiest (and cheapest) solution is to use DDWRT with a supported router like the Linksys WRT54G, just like the sailboat captain in our first question. Buy yourself two yagi antennas, with appropriate connections or adapters to plug into the two routers. Connect each antenna to a respective router in each house and aim them at each other. Chances are, this will do the trick. You may even be able to keep the yagis indoors, especially if you can position them by windows. Installing the yagis outdoors is a little more complicated because youll need to run the cable indoors to the router. If for some reason yagi antennas arent strong enough, or you need to connect a wireless link much longer than 600 feetsay, several milesyou can upgrade to a directional grid antenna. Reminiscent of a medium-sized satellite dish, a pair of grid antennas will cover a significant distance. But, as always with wireless, the more clear your line of sight, the longer a link you can achieve. n

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Coverage

Q

:Weusean802.11nDraft2networkwithcablebackhaulforourhome(andhomeoffice) network. When we upgraded our router from an802.11gLinksysmodeltoan802.11nDraft 2TrendNetdevice,wealsoaddedTrendNet802.11nclientupgradestoourcomputersonthenetwork(alaptop, and a desktop that sits in a location that is hard to reach withEthernet).Bothsystems received a definite and significant boost in signal strength and throughput; the connection was much faster and more dependable, particularly with the desktop because it sits the farthest from the router. About a year later, we upgradedtheRAMintheold gal(itsafive-year-oldXP desktopsystem)andtheWiFi signal strength doubled. We havent changed anything elseaboutlocation,settings,ISP,tinfoilbarriers,etc. except that we put up the antenna on a radio several feet away. Are we imagining the boost? Is it a fluke, is the radiosomehowassisting,orcanupgradingyourRAM(we nearlydoubledit)actuallyimproveyourWi-Fireception? Thanksforyourhelp.Yourule.NaimyandPeeps A: Fascinating! I enjoy a good mystery. Honestly, I cant think of any way that the RAM upgrade would influence signal strength one way or another. It doesnt add up, and I cant

find any citations online backing up such a possibility. The reason that n devices produce better range than pre-n devices is because the n-standard requires the use of MIMO technology. Basically MIMO means that multiple antennas are used. Depending on the model, all antennas may be external, or a mix of internal and external. The purpose of the antennas is to catch multipath reflectionsbasically, in the real world signals tend to bounce around rather than travel is a purely straight line. This is because they invariably hit reflective objects from glass to metal and so on.With preMIMO wireless, this multi-path effect resulted in reduced signal since only a portion of the original signal would reach the destination. MIMO captures the reflections and re-assembles the signal, thus improving performance and effective signal strength. It is actually possible that the radio antenna you mention is assisting--it could be producing a good signal reflection, almost like an amplifying effect. Some people have reported improved Wi-Fi signals when their cell phone is near the computer, for example, and this could be a similar kind of thing. Of course the only way to know for sure is to, you know, move the antenna and see what happens. We must also consider the possibility that the improved signal could be the result of an unknown variable--something else that did change, but you dont know it. Orientation of the PC after upgrade? Something subtle like a window screen up

The purpose of the antennas is to catch multipath reflectionsbasically, in the real world signals tend to bounce around rather than travel is a purely straight line.5

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or down elsewhere in the room, and so on. Still, the antenna theory at least has a plausible explanation, unlike the RAM upgrade. Q: I am desperately trying to find a wireless router to buy.IhavehadaBelkinDraft-nandaBelkinN1Vision.IfoundtheDraft-Nabetterperformancemachine. However, now I want to buy a new router that has great coveragefromamainhousetoanannexhouse.There arewallstoconsider.Ineedcoverageuptoabout150 feet. What is your personal choice? Nick A: One thing to note when setting up a wireless network is that range and speed are two different things and you may need to optimize for one or the other. In my experience, pre-N gear can do a good job with range, but is aggressive about reducing speeds to compensateso you may get a connection from a distance you couldnt with another router, but it might not be very fast. The reason pre-N gear is generally good at range, and obstacles, is because it uses MIMOor multiple antennasto capture reflected signal paths. You can also find MIMO on some enhanced g routers, which usually say so right in their name, like Super G with MIMO.

connect with the primary router for service. A third possibility would be to setup a wireless router in the annex house and use WDS to repeat the signal from the main house. You would be able to setup this annex router in an optimal position (and/or with a stronger antenna) to receive the signal, and your wireless clients could more easily pick up the rebroadcast signal. For a 150-foot range, one or any of these scenarios should do the trick. For longer distances, I would start to look at directional antennas like yagis to create a point-to-point link. But this seems like overkill at this distance unless your houses are actually underground fallout shelters. Which would be pretty cool, actually. Q:IamconnectedbyTimeWarner Cable to my system through a LinksysWRT54GLrouter.Iputon Tomatofirmwareandamtransmittingat84mW.Thissetupisinthe front of my house on the second floor. My basement is in the rear of my house. When Im in the basement, my laptop seems to pick up a better signal than my PC, but thespeeditabout25percentof upstairs. What can I do to get a stronger signal wirelessly down in thebasement?Someonesuggested using two routers, namely an n-draft router upstairs and placing my Linksys on the main floor just above my basementinmydiningroom.IsTomatogoodfirmware touseorshouldIinstallDD-WRTonarouterupstairsas well as the Linksys? Arthur A: For those readers who havent yet heard of Tomato, it is not only a nutritious and delicious vegetable (technically a fruit, but thats for some other guru to explain)Tomato is also an open source firmware, like DD-WRT. Where was I? It doesnt sound like the firmware is the problem in this situation. Whether you are using Tomato or DD-WRT, the challenge here is primarily environmental. Basements are especially challenging for reception of wireless signals, and in this case your router is two floors away. Bumping the transmit power to 84mW (the default is 28mW) is probably hurting more than helpingwhen you increase power, you increase both signal and noise. The reason your connection speed is reduced by is because your basement PC cannot negotiate a faster rate, which may

To get the most out of any router with MIMO, you need to use a wireless client with the same support.

To get the most out of any router with MIMO, you need to use a wireless client with the same support. (Its not clear from your question if you are also using the Belkin pre-N card at the other end.) I dont like to encourage vendor lock, but in practice, edge technologies like MIMO (and RangeMax) as well as pre-N seem to be most reliable when paired with companions of the same vendor. Besides all that, if your router has detachable antennas (the typical rubber ducky), you can swap them for longer, more powerful replacement antennas that can double or sometimes triple their sensitivity. This doesnt necessarily mean a doubling or tripling of your range, but it can help you squeeze out every last drop of performance. Try to orient your wireless router as high as possible in your main house, such as a top floor. Alternative possibilities could include adding a second wireless router to your main house, in a spot best for seeing the annex house (such as a window). This secondary router could use WDS (wireless distribution system) or an old-fashioned Ethernet cable to 6

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in part be due to interference from the extra noise. The suggestion you received is basically to add a second router into the mix, effectively re-distributing your wireless signal. You could do thisthere is more than one way to get it done. Using an n-draft router might offer some slight advantage for getting maximum signal to a router on your main floor, only because the n router will be using a superior MIMO antenna array; but your Linksys is not an n router, and so the benefit of doing this is not hugely compelling. Chances are that a second router just like your Linksys will do the job. If your second router supports WDS (wireless distribution system) you may not even have to muck around with flashing an alternative firmware (some stock routers support WDS out of the box). You can setup WDS between your new

router and your Tomato-based router, which should improve the signal to your basement. It may be heresy to say this, but Ive said it before so theres no turning back nowwhat about not going wireless to your basement? If you plan on living in this house for a long time, I would consider running Ethernet from the second floor to another router in the basement. Maybe even along the outer wall if it would be an easier install. In the long run (get it? long run!), this would be the most stable and fastest solution, particularly if you want to run a gigabit LAN. A third option would be to cable only from the second floor to first floorsee the question and answer below for a similar scenario. n

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Connections & Signal Boosting

Q

:IamtryingtouseWRT54Gv2/DD-WRTv24 antennaselectiontohaveoneantennaTX andtheotherRX.Doesthemenuoption whereyoucanselectTX/RXandLeft/Right antennas really do what it says? Namely can I have one antennaexclusivelyforTXandtheotherexclusivelyfor RX.Petar A: Truth in advertisingit is indeed true that DD-WRT lets you manually select which of the two WRT-54G antennas is assigned to sending (TX) and receiving (RX). More interesting still is not so much that you can, but why would you want to? It turns out there are several reasons one might do this, some useful and some perhaps not so much. First, it is important to clarify that wireless radios operate in half-duplex modethey cannot send and receive data at the same time. Instead, they switch between sending and receiving modes. Furthermore, only one antenna is used for sending. Routers that have two antennas (some have only one) are using diversity reception, which means that they dynamically switch between them to pickup the strongest signal, which may vary due to myriad environmental factors including multipath interference and reflection. Diversity mode is used for a reason, so if you are simply

using the stock rubber ducky antennas included with your router, there really is no advantage to manually assigning TX and RX to exclusive antennas, and effectively disabling diversity. However, in some scenarios you want to replace the stock antenna with a high-powered directional like a grid or yagi. Typically, this is done to create a long range wireless link, say between houses or office buildings. In this setup, you want to assign both TX and RX to the directional antenna and not bother with the second stock antennaand this is where DD-WRTs setting can become very useful, since the stock firmware does not let you make such an assignment. Oh, and you might be wonderingwhich antenna is the left one? The right one? With DDWRT, left and right are based on looking at the router from the front, where the LEDs are. However, other firmware might use the reverse orientation, looking at the router from the back. Of course, you have a 50% chance of guessing correctly, but to be sure, simply remove one antenna, and change the RX/TX assignments to see whether left or right works with just the one antenna. Q:IhaveaCradlepointMBR1000gatewaythatiswired to the desktop and works fine. I use it wirelessly to connect to a laptop and that works fine, but when I try to get myVaioPCGZ1VAtoconnect,itshowsinthetaskbar that it has a good signal, but I cant connect to the Inter-

Routers that have two antennas (some have only one) are using diversity reception, which means that they dynamically switch between them to pickup the strongest signal, which may vary due to myriad environmental factors including multipath interference and reflection.8

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net.IgetamessagethatstatesWindowswasunableto findacertificatetologyouontothenetwork.Canyou youhelpmeout?-Brad A: You have to admire Microsoft for keeping its Unhelpful Error Message Department busy, continually inventing new and ever more cryptic ways to tell you that what you want to do doesnt work. The clue here is certificate because, chances are, your wireless network does not use a certificate. And the problem is likely with the client PC in this case, your Sony Vaio, which may be misconfigured to look for a different kind of network than the one that you have. It isnt clear whether you are connecting to the wireless network using Windows built-in wireless management or the Intel PROset wireless connection utility preinstalled on the Vaio. If you are using the Windows connection utility, I would first try to switch to the PROset utility instead. Failing that, two things to consider: TheVaiomaybetryingtoestablishaWPA-RADIUSconnection rather than WPA-PSK (or WEP), depending on what kind of security you have in place on the Cradlepoint router. If the Vaio is mistakenly trying to make a WPA-RADIUS connection, and you arent actually using a separate RADIUS server (which is almost certainly the case), this error may appear. DisableIEEE802.1Xauthenticationonthewireless adapter for the Vaio. Open the available wireless networks, right-click on your network, choose Properties, and look for the Authentication tab, where you can hopefully uncheck 802.1X. Q: Most of the user manuals and instructions I have foundforwirelessrouters/gatewaysassumethattheInternetconnectionisviaEthernet/cablemodem.Ihavea wirelessISPandsowanttoaccesstheInternetthrough myLinksysWRT54GS.Ialreadyhaveahomewireless net using Airport Extreme. Can you give me a few hints onsetup?Jon A: One would need more precise information about your WISP (wireless ISP) to provide detailed instructions, but 9

on its face this seems like a relatively simple configuration to achieve. When you plug a cable/DSL modem into a wireless routers WAN/Internet port, the router requests an IP address from the ISPs server at the other end of the line. Depending on the protocol in use by that ISP, this request might take place by DHCP or PPPoE, among others, and so your routers Internet connection has to be configured accordingly. The situation is really no different with a WISP. Depending on the WISP, you probably have some kind of subscriber unit (SU) in your premises. This connects to the external antenna you use to receive the WISP signalor, in the case of some like Clearwire, the antenna might be integrated into the subscriber unit.

If your WISP uses DHCP to assign an IP address, your router will need to be configured likewise (this is usually the default setting).

Chances are that the SU provided by your WISP connects to your computer using an Ethernet cable. You can probably plug this cable right into your wireless routers WAN/ Internet port. If your WISP uses DHCP to assign an IP address, your router will need to be configured likewise (this is usually the default setting). If your WISP uses PPPoE, you should configure the router to use the same, with supplied username and password. There are other possibilities, but youd have to consult with your WISP for details. If your SU connects to a PC using USB rather than Ethernet (this shouldnt be very common), then this would not work with your wireless router. In that case, request an Ethernetbased SU from your WISP. Unless you need two wireless routers for some reason, in the above setup your WRT54GS should server your whole wireless net. The Airport Extreme would seem to be redundant.

Q: I was using my Linksys as my main router, but Im using a Netgear router now. I still use my Linksys as an accesspointbyturningofftheDHCPandjustpluggingthe cable into one of the four LAN ports. Now that Im using DD-WRT,IwantedtomakeanotheropenWi-Fipoint,but itsnotworking.--Dave A: The good news is that what you are trying to doconfig-

Get Answers to Your Wi-Fi Questions, an Internet.com Network eBook. 2009, WebMediaBrands Inc.

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ure a second router as a dumb wired access pointis perfectly legitimate. The bad news is that it isnt working. But it should, so we can take solace in that there must be a simple configuration oversight somewhere. You were right to disable the DHCP server on your second (AP) router. When it comes to DHCP servers on a LAN, you must always apply The Highlander Rulethere can be only one. But thats not allit is also a good idea to disable the firewall on your AP router. Security should be handled by the gateway (primary) router. It sounds like your cable is plugged into the correct portit must be a LAN port, and not the WAN or Internet port on the AP router. (You will not use the WAN/Internet port.) This also means that your AP router is not going to receive a DHCP assignment from your primary router, because it only listens for DHCP on its WAN/Internet port. You will need to manually configure your AP routers network address using an IP that is compatible with your primary router.

For example, suppose your primary router has the typical IP of 192.168.1.1 (and network mask 255.255.255.0). On your AP router, you will configure it with an IP address like 192.168.1.2 (same network mask). You may or may not need to specify an IP for gateway and DNS, but if you do, it is the IP of your primary router (192.168.1.1 in this example). For testing purposes, at least, you should also configure the wireless SSID on your AP router without any WEP/WPA/ WPA2 security. You can apply the security of your choosing after verifying the AP connection. Wireless clients who associate with your AP should receive their IP address and related settings (gateway, DNS) from your primary router. And you should be able to connect to your AP router using the IP address you manually assigned to it. n

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DD-WRT

Q

: I have to set up a temporary Wi-Fi hotspot at a seminar in a hotel. I would like to have some sort of bandwidth limit and an acknowledgement splash page, but no authentication. I would also like to have to bring as little equipment as possible.(Chilispotandotherhotspotserversmostly require another computer to run on. Im hoping to find something I can run on a router).IfoundNoDogSplash, which seems to fit my situation, howeveritlikesOpenWRT.It seemslikeDD-WRTisamuch morepolishedfirmware.Doyou thinkNoDogSplashwillrunon DD-WRT?Jason A: Lets first unpack this scenarioyou want to setup a single piece of hardware that will give nearby users wireless Internet access. But, you want to force them to see a splash page upon connecting (such as ads from sponsors), and you want to define limits on their upload and download speeds, presumably so that no single user can hog all the available bandwidth to the Internet. As you have discovered, NoDogSplash meets all of your needs, but with one catchit runs on OpenWRT, which is a less user-friendly router firmware than, say, DD-WRT (or Tomato). The OpenWRT learning curve is considerable

compared to these others, and although it is quite powerful, it may not be the most inviting choice for a turnkey solution. Unfortunately, it does not seem like anyone has posted a successful report of installing NoDogSplash on DD-WRT or Tomato. However, there are two alternative approaches to consider: FlashyourWRT54G-family router to CoovaAP. This opensource firmware is actually based on OpenWRT and includes a captive portal (for your splash page) and traffic shaping (for bandwidth limiting). But unlike OpenWRT, CoovaAP also includes a relatively user-friendly Web-based administration interface. StickwithDD-WRTand use NoCatSplash for the splash page, which can be hosted on an external Web server. Limiting bandwidth is slightly more complex (unless you buy the paid version of DD-WRT, which includes bandwidth management in the GUI). You can create an iptables script for limiting bandwidth by IP/MAC or other criteria using the nifty Windows app WRT54G Script Generator. Follow the step-by-step wizard to generate an iptables script which you can paste into DD-WRTs firewall script section. Like Jason says, most captive portal solutions require

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You can create an iptables script for limiting bandwidth by IP/MAC or other criteria using the nifty Windows app WRT54G Script Generator.

Get Answers to Your Wi-Fi Questions, an Internet.com Network eBook. 2009, WebMediaBrands Inc.

Get Answers to Your Wi-Fi Questions

interacting with an external server, most typically a RADIUS server. Q:IhavesetupWDSwithtworoutersusingDD-WRT sp1atmyfolkshouse,whichisinadifferenttown.Ican remote into the base router with their IP address:port, but I want to be able to access the second router from my house, as well.Doyouknowhowtodothisor do even understand what Im saying?-Bob A: I do understand! In fact, I have setup the very same arrangement for remote support. But first, lets be sure everyone else understands what were talking about, too.

One problem is that the remote administration service listens for connections coming in via the WAN or Internet port. On your primary router, this is your cable or DSL modem. But your secondary router probably has no connection on the WAN port.

Suppose you have one wireless router. Normally when you connect your browser to this routers administration interface you do so from a client inside your LANthat is, a client connected to the router. What if you want to connect to the browsers administration page from outside your LANin other words, remotely? Most routers, including those running DD-WRT, offer a separate configuration setting for remote administration that is often disabled by default. In DD-WRT, this setting lives under Administration/Management/Remote Access. You can customize the connection port, since the usual Web port (80) is reserved for local access. From outside the network, you connect to this router using the IP address assigned to the incoming broadband connection (or use a dynamic DNS service to translate the IP to a friendly name). Now suppose that the LAN in question is served by two wireless routers, configured to extend range through either a repeater or WDS configuration. You want to remotely admin the second router, but how do you address it from outside the LAN?

most captive portal solutions require interacting with an external server, most typically a RADIUS server.

The workaround is that you actually access your secondary router on its normal administration interface, instead of using remote administration. To do this, you need to set up port mapping (aka port forwarding) from your primary router to your secondary router.

Using DD-WRT, click on NAT/QoS and then Port Forwarding. You need to choose a public port that youll connect to from outside the network. In my scenario, the primary router is configured to accept remote administration on port 8080. So I decided to use port 8081 for remote access to the secondary router. My DD-WRT port forwarding configuration looks like this: Application: remote router 2Port from: 8081Protocol: TCPIP Address: 192.168.1.2Port to: 80Enable: Checked The IP address is the LAN address assigned to my secondary router. Be sure to click Apply Settings. Now, when I am outside the LAN and open a browser to http://myremotenetwork:8081, the primary router will forward that request to port 80 of the secondary router. VoilaI can log in to the secondary routers administration interface remotely, even though I am not technically using its remote administration. n

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Get Answers to Your Wi-Fi Questions, an Internet.com Network eBook. 2009, WebMediaBrands Inc.

Get Answers to Your Wi-Fi Questions

Mac/iPhone

Q

: I had a nagging problem with my sons MacBookdroppingwirelesswithasecurity compromisedmessage.Turnsout,mywifes laptop(XP)wascorruptingthenetworkwith VPN.AssoonasIswitchedtoAESversusTKIPthe problemdisappeared.NotsureifMacsdontdoTKIP well,orXPdoesnt...butAESisquitestable.Al A: Perhaps we ganged up on Microsoft error messages too soon. A good number of Mac users have reported frustration and confusion with the infamous Your wireless network has been compromised error. Whats worse, in fact, than Microsofts empty rhetoric is that this message actually causes OS X to disable your wireless network for one minute. Gee, thanks Apple! Of course, OS X thinks it is doing you a favor. After all, it has decided that your wireless network is being hacked by a nasty intruder, and so taking your machine offline is for your own good. The only problem is, chances are, that there is no intruder. Little seems to be known about the exact cause of this error, and Apple has yet to address it despite reports dating back to at least 2004. Some users are affected frequentlyas

in repeatedly, every daywhile others have never seen this error. Based both on my personal experience with this error and other user reports, it appears that the trigger involves the presence of a PC-based wireless client using WPA-TKIP. For example, at a friends house I had setup a wireless network using WPA-TKIP, and configured both her MacBook and my PC to the appropriate settings. The MacBook would connect to the network, but as soon as my PC would connect, the Mac would throw the security error and shut down her connection. As Al discovered himself, changing all parties involved the router and the clientsto WPA-AES encryption solved the problem and everyone got along happily. The question remains, though, is TKIP encryption tickling a bug in OS X? Have you seen this error on a Mac and found any other solution and/or explanation? Considering how widely used TKIP is (as the default WPA encryption scheme in most wireless routers), it seems odd that this bug would persist in OS X for so many years. If you have insight to share, click on my byline above to send us your feedback, or use the Comments tool below.

A good number of Mac users have reported frustration and confusion with the infamous Your wireless network has been compromised error.13

Get Answers to Your Wi-Fi Questions, an Internet.com Network eBook. 2009, WebMediaBrands Inc.

Get Answers to Your Wi-Fi Questions

Q: When using the iPhone internationally, is there a way to be sure youre on Wi-Fi and not using the phone network? I know that icon is at the top for the Wi-Fi, but can you turn off the phone so youre sure youre not popping minutesandMBoffatahugecost?--Tom A: Even the most devout iPhone lovers would be less than thrilled to receive a $4,800 bill for international data roaming. The iPhone uses both the cellular EDGE network and local Wi-Fi for network access. Although connecting to a wireless AP may be free, using EDGE will incur data charges if you are roaming internationallybig charges. Even though the iPhone will prefer Wi-Fi over EDGE when available, it still must rely on EDGE for features like updating visual voicemail. Unfortunately, Apple did not build a simple hardware or software switch into the iPhone so that you can manually disable EDGE. From what I hear, it is possible to arrange for your

cellular contract to disable international roaming, although this could be inconvenient if you would like spontaneous control over using data roaming. Fortunately, there are two other solutions: 1. Brute forcepull the SIM card. If you remove the SIM from your iPhone, it will not be able to get onto the cellular network. Reports suggest that you can continue to use the iPhone as a network client via Wi-Fi. Of course, this means you also wont be able to make calls using your iPhone until you reinsert the SIM card, making it not so much of a phone and more just an i. 2. Users of an iPhone running 1.x firmware can install the Services app, which gives you a nifty little GUI through which you can toggle EDGE, Bluetooth, and Wi-Fi. iPhone 2.x users will need a different app, called BossPrefs, to do the same thing. n

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Get Answers to Your Wi-Fi Questions, an Internet.com Network eBook. 2009, WebMediaBrands Inc.