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Concentrating Network Access Through an Overdrive Pro 3G/4G Mobile Hotspot

Recently, I was asked to assist with setting up a Mobile Hotspot. In some areas, there are still not reasonable broadband connectivity options. In times past, that meant dial-up access only. More recently, the feasibility of mobile broadband connections serving as a home internet connection has increased. This precise case scenario was what I was presented with.

This particular use-case was with a Virgin Mobile Overdrive Pro 3G/4G hotspot, made by Sierra Wireless. Entering the situation, all clients in the home were connecting to the hotspot via WiFi. The Overdrive Pro supports a maximum of 5 client connections at a time. This itself presents a possible issue in modern homes, where many devices end up connecting to the home network via WiFi. Additionally, placement of the mobile hotspot (combined with its somewhat limited WiFi range) meant that ideal positioning of the hotspot for broadband signal potentially compromises WiFi performance locally.

Enter DD-WRT (http://www.dd-wrt.com), a custom firmware for many different router manufacturers and models, originating on the classic WRT-54G wireless routers that I’m sure everyone has seen (or certainly been piped through) at some point. This firmware has many abilities above and beyond your router’s factory firmware, not all of which I will cover here. However, one such feature that I will highlight here, is its ability to serve as a Wireless Repeater.

My solution plan was to utilize a DD-WRT equipped wireless router to service the WiFi network within the home. It would connect wirelessly to the Overdrive Pro mobile hotspot. Then, it would route locally connected traffic through the hotspot connection and out to the internet. This solution provided many beneficial features:

  • Overdrive Pro 3G/4G positioning could be tailored to the best possible broadband signal. As long as the DD-WRT router was able to get a WiFi signal to the Overdrive Pro, we were golden.
  • If the Overdrive Pro fails for some reason, in-house WiFi is still maintained by the DD-WRT router.
  • Key Feature: The Overdrive Pro only sees the DD-WRT router as its single WiFi client connection. Multiplexing the connection through the DD-WRT router means that you can run as many devices through it as you want. Granted, you don’t have a lot of throughput available, but it is easy to consider multiple devices nowadays needing to have periodic connectivity (tablets, phones, e-readers, etc, along with your computers on the network).

Lets get right into the meat and potatoes. Happy

First, you must setup your Overdrive Pro 3G/4G hotspot as per the setup guide that it comes with. You’ll essentially want to make sure that you can indeed connect to the WiFi hotspot and get out to the internet. Once you have that working, locate your DD-WRT router. There are many choices for routers that can run DD-WRT. Check the Router Database (http://dd-wrt.com/site/support/router-database) on the DD-WRT website to see if the model you’re looking at supports the custom firmware. Be cautious when looking at model numbers though, as the particular hardware revision needs to be supported for your router as well. One key example is the very common WGR614 Netgear router--only a few of the hardware revisions are supported. Similarly, even some of the hardware revisions of the Linksys WRT-54G router are not supported, surprisingly enough. Just check carefully, otherwise your expensive router might not be able to offer the extended functionality you seek!

Once you’ve located a suitable router, get DD-WRT installed onto it. Typically, you can load the firmware through the stock router’s web-based firmware update utility. Make sure to check your specific router version for installation instructions, as they can vary from model to model! Now we’re ready to get onto the setup portion. The guide below has been adapted from the DD-WRT wiki for setting up a Repeater Bridge (http://www.dd-wrt.com/wiki/index.php/Repeater_Bridge)

DD-WRT Router Configuration
  • Set your computer to a static IP address within the DD-WRT router’s default IP range--192.168.1.10 will put you on the 192.168.1.0/24 subnet that the DD-WRT router configuration will default to. Connect your ethernet cable from your computer to one of the switch ports on the router.
  • Once connected, open up http://192.168.1.1 in your web browser. Configure the administration username and password when prompted--this step is required for first-time setup of the DD-WRT router.
  • You should now see the main interface. Open up the Wireless -> Basic Settings tab and configure the following settings:
    • Physical Interface Section
      • Wireless Mode: Repeater Bridge
      • Wireless Network Mode: Mixed
      • Wireless Network Name (SSID): OverdrivePro95A (this should be whatever you configured your hotspot wireless SSID for)
      • Wireless SSID Broadcast: Enable
      • Network Configuration: Bridged
      • Save (DO NOT CLICK APPLY SETTINGS YET)
    • Virtual Interfaces Section
      • Add
      • Wireless Network Name (SSID): (Pick the SSID you wish to use for your home network, should be different than the Overdrive Pro SSID)
      • Wireless SSID Broadcast: Enable
      • AP Isolation: Disable
      • Network Configuration: Bridged
      • Save (DO NOT CLICK APPLY SETTINGS YET)
  • Next, open the Wireless -> Wireless Security tab and configure these settings:
    • Physical Interface Section
      • Security Mode: WPA2 Personal - The default security configuration for the Overdrive Pro 3G/4G is WPA2 with AES algorithm.
      • WPA Algorithm: AES - Use this unless you have modified your hotspot security with different settings
      • WPA Shared Key: <CUSTOM> - Enter the passphrase you use to connect to your hotspot.
    • Virtual Interfaces Section
      • Security Mode: WPA2 Personal
      • WPA Algorithm: AES
      • WPA Shared Key: - This is the passphrase you wish to use for your home WiFi network
      • Save (DO NOT CLICK APPLY SETTINGS YET)
  • We now must set the IP configuration of the router itself. Go to the Setup -> Basic Setup tab and make the following adjustments:
    • WAN Connection Type
      • STP: Disable
    • Router IP
      • Local IP Address: 192.168.0.2 (The Overdrive Pro 3G/4G hotspot will typically be at 192.168.0.1)
      • Subnet Mask: 255.255.255.0
      • Gateway: 192.168.0.1 (address of your hotspot)
      • Local DNS: 192.168.0.1 (address of your hotspot)
      • DHCP Server: Disable
    • Save (DO NOT CLICK APPLY SETTINGS YET)
  • At this phase, you will have to log back into your router under the new IP address. Reconfigure your computer’s address to now be on the 192.168.0.0/24 network, with an IP address of, lets say, 192.168.0.10.
  • Once logged back in, there are only a couple additional settings. Go to the Setup -> Advanced Routing tab:
    • Operating Mode
      • Operating Mode: Router
    • Save (DO NOT CLICK APPLY SETTINGS YET)
  • Disable some unneeded services under the Services -> Services tab:
    • DNSMasq
      • DNSMasq: Disable
    • Save
    • Apply Settings (Don’t tell you haven’t been waiting to click that through this whole procedure, indulge yourself now)
  • The router will now restart, and once it comes back, it should connect automatically to the WiFi hotspot of the Overdrive Pro device.

Once the router restarts, you should be able to configure your computer back to a dynamic IP address, and also (if you have a WiFi interface) connect to the SSID you configured for your home network. If all went correctly, you should now see the Overdrive Pro indicating only one client connection, which is the connection from your DD-WRT router. Reconfigure any other WiFi devices in your home network to connect to the DD-WRT SSID (that you added in the Virtual Interfaces section of the wireless configuration) instead of the Overdrive Pro.

Optional Steps
  • Now that everything is working well, you might want to disable the SSID broadcast on your Overdrive Pro device, since you won’t be connecting to it any longer with WiFi. Go into the Overdrive Pro web configuration (should still be at http://192.168.0.1) and find the Advanced Settings -> WiFi -> Network tab:
    • SSID Broadcast: Disable

IMPORTANT: If you are using your Mobile Hotspot as a permanent fixture and plan to have power connected to it full-time, make sure to remove the battery (powering the device solely on the included charger), as it will overheat if you leave the unit connected to the charger (with the battery in place). Also, make sure that you use the proper amperage charger (the one included with the device is 1.2A I believe), as lower-amperage chargers might power the device, but will fail to power the broadband antenna enough to get you a signal.

Hopefully this guide helps anyone who has limited access to broadband internet get online and cooking. There are many other features of the DD-WRT router firmware, this is just one taste of what can be done--I hope to bring some more case-specific feature expositions to PureLinux in the future! Enjoy!

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