[plug] Safely using an untrusted router

Thu Oct 22 08:25:51 UTC 2015

Thanks Bill,

Your setup looks a bit too complicated for me as well :)  ...but good to
know iiNet are assigning private IP addresses to their mobile users.

Is the VPN just between your VM and your phone?  Interesting
idea, although I'm not sure Android would be the safest bet :)  ...oops, I
hope I didn't start any Android v iPhone pie-slinging :)

Anyway, I think I'm going to pursue the 4G USB modem idea for now, and see
how I go.

Thanks everyone so much for your ideas and comments.  I didn't mean for my
wee little Qu to dominate the PLUG forum, and I kinda feel like
I'm stretching my welcome a little bit for a first time contributor, so I
do apologise to all who put up with me the last few days.

But if the group is ok with it, and anyone has any further ideas, or
feedback on the 4G USB modem approach, please don't hesitate to let me know.

Cheers, Dirk

On Thursday, 22 October 2015, Bill Kenworthy <billk at iinet.net.au> wrote:

> my iinet mobile (GalaxyS5 with cyanogenmod) is using a 10.160 private
> address - I have no problems running openvpn over it to a vm inside my
> network (including security camera video over the vpn when I want to
> take a peek).  I am using a Cisco 1841 with an alcatel speadstream
> bridged with the router doing pppoe to iinet.  Stable but I need to work
> on the QoS more.
>
> BillK
>
>
>
> On 22/10/15 07:12, Dean Bergin wrote:
> > Hello Dirk,
> >
> > This is probably not going to help solve your particular issue, but one
> > thing I recently did, was install OpenWRT on a Rpi2 and set up PPPoE
> > over one of two subinterfaces (VLAN) to a cheap netgear modem (with the
> > help of a Cisco Catalyst switch). I also put the Rpi2 OpenWRT
> > effectively into it's own routed subnet/DMZ (part of the design) so that
> > even if there where to be some kind of funny business, things like uPNP
> > theoretically should not work since my experience has taught me that
> > most consumer-grade modems/routers do not route/NAT anything other than
> > their resident subnet, therefore I believe that not only are uPNP
> > implementations (and many other services on consumer-grade routers)
> > usually bound to the subnet to which they are running on, but should be
> > disabled in cases where the device is in pass-through mode.
> >
> >>Does anyone know whether 4G modems (and smart phones, for that matter)
> > are assigned a publicly-routable IP address or are they
> > typically NAT'd behind a small number of IP addresses of the mobile
> > service provider's servers?  I can't imagine billions(?) of mobile
> > phones all having unique publicly-routable IP addresses (on top of all
> > the servers and so on, around the world).
> >
> > I had the opportunity to test this, as I was able to tether my phone to
> > a Rpi2 running OpenWRT as part of the labs I did for my now current
> > nework design, but I did not think to test this specific scenario.
> >
> > Shouldn't be too difficult to create a lab to test this, if someone has
> > a spare raspberry pi (mine is currently in 'prod' now)?
> >
> >
> > On Wed, Oct 21, 2015 at 6:27 PM Dirk <justanothergreenguy at gmail.com
> <javascript:;>
> > <mailto:justanothergreenguy at gmail.com <javascript:;>>> wrote:
> >
> >     Thanks Andrew.  Will follow up on those ideas too, thanks.
> >
> >     However, I have another idea, a bit left field, but it may just do
> >     the trick...
> >
> >     Does anyone know whether 4G modems (and smart phones, for that
> >     matter) are assigned a publicly-routable IP address or are they
> >     typically NAT'd behind a small number of IP addresses of the mobile
> >     service provider's servers?  I can't imagine billions(?) of mobile
> >     phones all having unique publicly-routable IP addresses (on top of
> >     all the servers and so on, around the world).
> >
> >     If they're NAT'd, then maybe a pre-paid 4G USB modem dongle would be
> >     the way to go for low MB critical online work, eg. fetching package
> >     lists, logging in to ASIC, ATO, webmail, our utilities, etc.  Should
> >     block all scanners on the net that are looking for routers to
> >     exploit, by virtue of sitting behind the Svc providers routers.
> >      (...and then use an unsecured computer and ADSL router pair for
> >     general web browsing, content streaming, etc).
> >
> >     Does anyone know if this would work?
> >
> >     (Of course, if a 4G dongle is not NAT'd then I don't really gain
> >     anything).
> >
> >
> >
> >
> >     On Wednesday, 21 October 2015, Andrew Cooks <acooks at gmail.com
> <javascript:;>
> >     <mailto:acooks at gmail.com <javascript:;>>> wrote:
> >
> >         On Wed, Oct 21, 2015 at 9:43 AM, Dirk
> >         <justanothergreenguy at gmail.com <javascript:;>> wrote:
> >
> >
> >             Cheers for that Pavel.  And thanks again Brad for your
> >             input.  You've both given me some ideas, although I was
> >             hoping for an easy OpenVPN option  :)
> >
> >             If anyone else has any thoughts or suggestions, please let
> >             me know!
> >
> >         My internet access is slow enough, so I'm not really excited
> >         about pushing everything through a VPN.
> >
> >         I trust my router. I have a TP-Link TD-8817 modem in bridge
> >         mode, connected to a fit-pc
> >         (http://www.fit-pc.com/web/solutions/multilan/) running IPFire
> >         (http://www.ipfire.org/). IPFire tells me I can trust my DNS.
> >         IPFire packages are kept up to date. The modem could conceivably
> >         modify the PPPoE frames in transit, except that it's a dirt
> >         cheap consumer product with little functionality that could be
> >         exploitable and it's unlikely to have enough processing power to
> >         do that kind of thing.
> >
> >         There is nowhere safe, only acceptable risks.
> >
> >         a.
> >
> >     _______________________________________________
> >     PLUG discussion list: plug at plug.org.au <javascript:;> <mailto:
> plug at plug.org.au <javascript:;>>
> >     http://lists.plug.org.au/mailman/listinfo/plug
> >     Committee e-mail: committee at plug.org.au <javascript:;> <mailto:
> committee at plug.org.au <javascript:;>>
> >     PLUG Membership: http://www.plug.org.au/membership
> >
> > --
> >
> > Kind Regards,
> >
> > /Dean Bergin/.
> >
> >
> >
> > _______________________________________________
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> >
>
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