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posted by LaminatorX on Friday March 28 2014, @03:05PM   Printer-friendly
from the man-ip dept.

mlosh writes:

I've got a Samsung Galaxy Note 10.1 (2014) and would like to connect to a private network through WiFi for development work, but still have access to the general Internet through the 3G/4G cellular radio for other apps. So far, it does not seem possible. Connecting to WiFi seems to route all data through WiFi to the private network, cutting off the Internet. Is there a way to have both radios working and routing packets separately on this Galaxy Note, or any other Android device, short of customizing the network stack software?

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  • (Score: 4, Funny) by NullPtr on Friday March 28 2014, @03:13PM

    by NullPtr (3786) on Friday March 28 2014, @03:13PM (#22542) Journal
    • (Score: 5, Insightful) by Zyx Abacab on Friday March 28 2014, @03:25PM

      by Zyx Abacab (3701) on Friday March 28 2014, @03:25PM (#22546)

      What GP said - this isn't a question that readily sparks discussion. Still, you might be able to use AFWall+ [f-droid.org] to your advantage; it has fine-grained controls for several connection types, including WiFi and 3G/4G. It requires a rooted device, though.

      For example, you could set your Happy Birds app to be restricted to WiFi and VPN only, but let Firefox to connect over anything.

      • (Score: 1) by mlosh on Friday March 28 2014, @05:38PM

        by mlosh (3364) on Friday March 28 2014, @05:38PM (#22607)

        Don't plan to root my tablet just for this! But yeah, I wan't more control over gateway settings and such than I can see in the default load of Android 4.1 on the Galaxy Note.

        And, yeah, I'll have to spend more time on StackExchange, like the GP said. First pass through there didn't look too promising, though.

        • (Score: 3, Informative) by tbuddy on Friday March 28 2014, @06:09PM

          by tbuddy (932) on Friday March 28 2014, @06:09PM (#22624)

          If you don't want to root you can just stop the search now.

          • (Score: 2, Interesting) by NullPtr on Friday March 28 2014, @09:08PM

            by NullPtr (3786) on Friday March 28 2014, @09:08PM (#22699) Journal

            And ask yourself "why would I have an Android phone, and read tech sites such as Soylent News....and yet not want to root my phone?"

            • (Score: 1) by mlosh on Sunday March 30 2014, @01:21AM

              by mlosh (3364) on Sunday March 30 2014, @01:21AM (#22998)

              Well, I just got this Android tablet from my employer, and have not used Android before, beyond playing with demo models at shows and stores. I've been using Linux heavily as a developer for desktop and embedded stuff, but a lot of things are different in Android-land. My phone's an Apple (and Blackberry before that). So I'm a bit reluctant to root this tablet as my first step. Maybe later!

  • (Score: 5, Funny) by dyingtolive on Friday March 28 2014, @03:31PM

    by dyingtolive (952) on Friday March 28 2014, @03:31PM (#22549)

    "My phone has too much battery life."

    --
    Don't blame me, I voted for moose wang!
    • (Score: 1) by dyingtolive on Friday March 28 2014, @03:34PM

      by dyingtolive (952) on Friday March 28 2014, @03:34PM (#22550)

      Err... tablet.

      --
      Don't blame me, I voted for moose wang!
  • (Score: 4, Insightful) by growlor on Friday March 28 2014, @03:51PM

    by growlor (1350) on Friday March 28 2014, @03:51PM (#22556)

    If it is an employer network (or other private network that you don't "own"), make sure they are OK with your phone being a bridge into their network (that isn't necessarily part of their security controls.)

    • (Score: 1) by mlosh on Friday March 28 2014, @05:41PM

      by mlosh (3364) on Friday March 28 2014, @05:41PM (#22608)

      Good point. In my case I'd want to make sure that no packets get routed between the Internet and the private network. The private network is isolated and offline. :-)

  • (Score: 5, Interesting) by Foobar Bazbot on Friday March 28 2014, @03:52PM

    by Foobar Bazbot (37) on Friday March 28 2014, @03:52PM (#22557) Journal

    I haven't tried the exact situation you're dealing with because I don't have (and don't really want) Android on a phone, but I have tethered an Android tablet to my phone with bluetooth (pan, iirc, but could have been dun), and simultaneously set up a wifi connection to scp a file to a bt-less laptop.

    The problem I encountered was only that the Android front-end is designed around "normal" use-cases, and can't be used to set up a wifi connection without tearing down the bluetooth connection. But using the "normal"/deprecated linux network tools (ifconfig, iwconfig) in the obvious way, it was possible to set up an ad-hoc wifi network with the laptop.

    I did this only once, a year or more ago; unfortunately I have no documentation beyond my own memory, and it didn't much testing, but it seemed to work fine. Perhaps it will at least provide a direction for you to start experimenting...

  • (Score: 4, Informative) by Anonymous Coward on Friday March 28 2014, @04:05PM

    by Anonymous Coward on Friday March 28 2014, @04:05PM (#22564)

    This is a complicated issue, related to the more general concept of running different connections through different network connections.

    The most basic way is to set the "metric" parameter of each network connection - presumably, your wifi connection has a low metric value, so it gets used first. The cell phone network has a higher metric, so it only gets used if the wifi is disabled, or when the wifi doesn't provide a default route.

    It sounds like you want to use the cell phone connection by default, and use the wifi only for the local network. You should set the wifi connection to have a higher metric (like 20), and the cell phone radio to have a lower metric (like 10).

    If you only want to access hosts on the same subnet as the wifi network, (for example, all on the same 192.168.X.Y network), then you're done. If you have a list hosts not on that subnet, which you also want to access over wifi, then manually add each host to the routing table:

    route add devbox.example gw 10.8.6.4 metric 1

    Assuming your wifi network's gateway is 10.8.6.4, and the host you want to contact is "devbox.example".

    Since the metric is 1, it will take this route with a higher priority than the metric 10 default route provided by the cell phone network.

    • (Score: 1) by mlosh on Friday March 28 2014, @05:35PM

      by mlosh (3364) on Friday March 28 2014, @05:35PM (#22604)

      Yes, you have the basic scenario right. Configuring this metric parameter looks worth exploring. Thanks for the big hint!

      Do you or any other readers know how to configure this in Android 4.1? I don't need to access any other nodes beyond a simple subnet in WiFi, so the extra routing table entries should not be needed. I'd like to configure the gateway address of each network independently too.

      • (Score: 1, Informative) by Anonymous Coward on Friday March 28 2014, @07:26PM

        by Anonymous Coward on Friday March 28 2014, @07:26PM (#22642)

        Skip the metric stuff, that only matters for complicated routing and this ain't complicated. You can ignore that part of the AC's post and just stick to the basics:

        1) Set the default route to point to the gateway to the cell network.
        2) Add a specific route for the development network to the gateway on the wifi network (like the AC's example, just leave off the metric option, or leave it on, it isn't really do anything)

        • (Score: 1) by mlosh on Friday March 28 2014, @09:21PM

          by mlosh (3364) on Friday March 28 2014, @09:21PM (#22712)

          Yes, thanks, this is probably what I want. I need to set up the route tables to have different gateways for each network device (like I have done with traditional Linux systems before).

          The GUI user-level settings app in Android does not let you do this, but it seems that if I install and use the Android Debugging Bridge (ADB) I can use a PC to open a shell and issue the route table change commands... hopefully without rooting and can be made permanent through a startup script or something.

    • (Score: 0) by Anonymous Coward on Friday March 28 2014, @05:37PM

      by Anonymous Coward on Friday March 28 2014, @05:37PM (#22606)

      Has anyone added BGP support for phones? This is much easier once you have created a personal ASN and eBGP peer with something on both networks.

      Make sure to filter properly so you do not provide a path to internal resources if they are using non-RFC1918 address space.

    • (Score: 0) by Anonymous Coward on Saturday March 29 2014, @03:07AM

      by Anonymous Coward on Saturday March 29 2014, @03:07AM (#22802)

      how the fuck did this get modded up to 4?! it is completely wrong. this has ab-so-fucking-lutely nothing to do with metrics. none.

      routing tables are matched most specific to least. that does all the stuff you're babbling about up there. metric not related.

  • (Score: 1) by SuddenOutbreak on Friday March 28 2014, @06:40PM

    by SuddenOutbreak (3961) on Friday March 28 2014, @06:40PM (#22630)

    I know it raises costs dramatically, but if one is for dev work then maybe you really need one tab for dev work and one for the cellular access?

    OTOH, rooting it would let you switch WiFi and cellular profiles pretty easily; you could even have multiple variations of the OS/ROM and bounce among them.

  • (Score: 1, Informative) by Anonymous Coward on Friday March 28 2014, @07:10PM

    by Anonymous Coward on Friday March 28 2014, @07:10PM (#22637)

    It sounds as if your private network does NOT provide Internet access, and you'll only be traversing the local subnet. If you do NOT need to access anything other than a single subnet, why not just CHANGE the gateway for your local WiFi so that it points to the gateway of the 3G network instead?

    http://androidwidgetcenter.com/android-tips/manual ly-add-ip-address-android/ [androidwidgetcenter.com]

    So anything you access locally won't need to hit a gateway router, and anything ELSE you need will have to head out on the Internet. .... Except that it doesn't seem Android wants to hold more than one IP address at a time?

    Hmm, so maybe not. :(

    http://stackoverflow.com/questions/10053643/can-wi fi-direct-and-3g-data-session-concurrently-work [stackoverflow.com]

    http://stackoverflow.com/questions/9266898/enable- simultaneouly-wifi-and-3g-interface-on-android [stackoverflow.com]

    http://stackoverflow.com/questions/12183647/-conne ct-issue-with-3g-and-wifi-simultaneous-usage [stackoverflow.com]

    Starting to look like bad news...

    Of course, what you COULD do is set up your own WiFi router that handles this split for you, acting as a client on the office network (with their permission I hope) and passing Internet requests through the phone's 3G. But that's assuming you're using a second device. :(

  • (Score: 1) by Nikker on Friday March 28 2014, @08:42PM

    by Nikker (227) on Friday March 28 2014, @08:42PM (#22686)

    Check out this paper. http://www.mit.edu/~medard/papers2011/Modeling%20N etwork%20Coded%20TCP.pdf [mit.edu]

    Also I remember an article on the 'other site' that mentioned a way of seamlessly handing off between separate networks but the server had to be configured for it. Can't seem to find the link right now though, apparently it is already part of the mainline kernel.

  • (Score: 1) by Baron Cheese on Saturday March 29 2014, @02:26AM

    by Baron Cheese (3998) on Saturday March 29 2014, @02:26AM (#22786)

    from http://www.connectify.me/dispatch/ [connectify.me]
    "Connectify Dispatch is an easy-to-use software load balancer that lets you use from all your computer’s Internet connections at the same time. Got Wi-Fi AND 4G? Two Wi-Fi adapters? Ethernet AND 3G? Connectify Dispatch will work with any and all of these technologies to increase your bandwidth."

    I haven't used it personally but seems legit.

    • (Score: 1) by Baron Cheese on Saturday March 29 2014, @02:30AM

      by Baron Cheese (3998) on Saturday March 29 2014, @02:30AM (#22789)
    • (Score: 0) by Anonymous Coward on Saturday March 29 2014, @03:38PM

      by Anonymous Coward on Saturday March 29 2014, @03:38PM (#22900)

      No.

      That's for "channel bonding" -- using two different connections to the internet in order to increase speed. That's a completely different application.

      Please don't just randomly google stuff and post it unless you actually know what's going on. Soylent is supposed to have GOOD comments, not the same random crap from the uneducated masses that we can get on yahoo answers.

  • (Score: 0) by Anonymous Coward on Saturday March 29 2014, @10:52PM

    by Anonymous Coward on Saturday March 29 2014, @10:52PM (#22959)

    This app allows to download simultaneously youtube videos on two connections (it can even use the connections of multiple phones !) https://play.google.com/store/apps/details?id=com. shoelacewireless.app.videobee [google.com]

  • (Score: 1) by mlosh on Sunday March 30 2014, @01:36AM

    by mlosh (3364) on Sunday March 30 2014, @01:36AM (#23006)

    I've found out I can get a command shell running on a PC to connect to my Android tablet... it's called Android Debug Bridge (adb) and is part of the Android software Development kit (SDK). I've downloaded it and can use it to get "under the hood" of the Galaxy Note to see the network settings and hopefully configure each network interface the way I want, using many of the Linux commands I'm familiar with. We will see this coming work week when I can try it out with my target environment. Just wanted to share this in case there are others out there who want to do "power user" things short of building new aps or customizing Android itself.