[plug] (no subject)

Dirk justanothergreenguy at gmail.com
Sun Oct 25 12:28:13 UTC 2015


Hi <yonjah>,

This is really in reply to anyone who still doesn't understand...

My approach is not complex, but it is time-consuming, I'll admit.  But any
sysadmin worth their salt should be doing similar things, establishing
verified, trusted copies of the OS install file(s) and security updates,
creating trusted system backup images, securing their network devices and
policies, etc.  Nothing unusual other than that it's for a home setup
dedicated solely for limited important online work (online banking, etc).

I've mentioned the threat or exposure in just about every email in this
thread:  an untrusted SOHO router.  Have a look at
http://routersecurity.org/bugs.php.  A cursory scan will show you how many
SOHO routers are vulnerable or are being actively exploited by whoever (it
doesn't really matter who).  How can one reconcile all these
vulnerabilities and exploits with a network policy that refuses to accept a
SOHO router may not be trustworthy?

ATMs aside, would anyone use XP for their online banking?  Of course they
wouldn't, but we don't need to define the threats, the actors, perceived v
real risks, ad infinitum, to justify that decision.

I agree <yonjah> that MD5 is broken, but it's only really an issue for
small files, passwords, server certs, etc, that can be modified and MD5'd
many times a second in the search for a collision.  But no-one's gonna run
millions and millions of modified 1GB .iso files thru MD5, trying to
generate a collision, although I guess they could work with an intermediate
checksum (e.g. for the 1st 990MB, and then continue the hash with millions
of variations for the remaining bytes).  Anyway, I do use SHA algorithms
(or some combination of them) as well, especially for smaller files.

Btw, there are theoretically billions of collisions no matter whether you
use a 128, 160, 256, 384, or 512-bit checksum.  All of these checksums have
by definition a finite number of outputs (e.g. 2^512), but you can feed in
an infinite range of file data, so a vast number of collisions must be
possible whether it's MD5 or SHA512.  They're just very very rare,
especially with the larger outputs.

Cheers, Dirk



On Friday, 23 October 2015, ıuoʎ <yonjah at gmail.com> wrote:

> Sorry, didn't notice I replied personally to you.
> You can reply publicly on the list
>
> On Fri, Oct 23, 2015 at 2:58 PM, Dirk <justanothergreenguy at gmail.com
> <javascript:_e(%7B%7D,'cvml','justanothergreenguy at gmail.com');>> wrote:
>
>> Hi <yonjah>, do you prefer I didn't respond via the PLUG list?
>>
>>
>>
>> On Thursday, 22 October 2015, ıuoʎ <yonjah at gmail.com> wrote:
>>
>>> Dirk.
>>> You keep mentioning MD5 for checksums. As far as I know MD5 is horribly
>>> broken and should not be trusted.
>>> Any way it is still not clear what threat you are trying to protect.
>>> Preventing your router from joining a bot net ? all the protection
>>> you'll to your pc connection are meaning less
>>> Protecting your communication from point A to B ?
>>> From who ? from you next door neighbour ? your ISP disgruntled employee
>>> ?a big and unnamed government agency ?  The measurements your going to take
>>> are going to be different for each adversary and for a big enough player
>>> anything you'll do wont be good enough but for average to small one we have
>>> plenty of good and simple solution to securily communicating from A to B
>>> without trusting any node on the way (which method depends more on B and
>>> what kind of control you have over it)
>>>
>>> Your setup sounds highly complex and sometime and can actually be
>>> damaging.
>>>
>>> On Thu, Oct 22, 2015 at 8:57 PM, Dirk <justanothergreenguy at gmail.com>
>>> wrote:
>>>
>>>> Hi Bill,
>>>>
>>>> Your setup probably makes a lot of sense for your needs, but I don't
>>>> need to remote out or remote in, or support VoIP, or support multiple
>>>> platforms.  It's just one PC and a modem router.  There should be a simple
>>>> solution.
>>>>
>>>> I wipe and restore my throwaway Linux OS and swap part'n after each
>>>> online session, and restore a fresh trusted MBR each time.  The
>>>> throwaway OS is updated offline using verified package lists and security
>>>> update .deb's from previous sessions (from CD, not USB).  My Mint ISO is
>>>> a verified good copy (MD5).  And yet I'm experiencing corrupted package
>>>> lists, so I can only suspect my BIOS or the router.  I don't think BadUSB
>>>> exploits are circulating as yet, so the mouse and keyboard should be fine.
>>>> I'm careful where I browse and what I click on when using this PC.  Java,
>>>> Flash, JavaScript (unless req'd), application launching in the
>>>> browser, linked fonts, smbd, avahi-daemon, auto-mounting, etc etc are all
>>>> disabled.  I'm far less concerned when I'm using other devices with my wifi
>>>> router, as I don't log into anything important with them.
>>>>
>>>> So my consumer / SOHO modem router is by far the weakest link.  It's
>>>> secured as best as possible (re UPnP and WAN-side admin disabled, strong
>>>> admin password, no wireless functionality, unsolicited packets are
>>>> dropped, etc etc), but the firmware is well out of date (no surprises
>>>> there, most are), and hackers are turning their attention to SOHO routers,
>>>> coz most people wouldn't know it if their router was hacked and added to a
>>>> botnet (or whatever);  e.g. AV doesn't reach into the router.  SOHO routers
>>>> are the new low-hanging fruit for hackers.
>>>>
>>>> So I don't think it's all that unreasonable for a SOHO to regard their
>>>> SOHO router as untrusted (i.e. like anyone needing to connect thru an
>>>> untrusted hotel (W)LAN, for instance), and to seek a solution that allows
>>>> for such untrusted elements, as per my original post.
>>>>
>>>> You are of course right.  There are many many areas of risk apart from
>>>> the router.  But what other vulnerabilities can I address?  What do you
>>>> mean by 'real risks', if not what I'm already addressing above?
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Thursday, 22 October 2015, BillK <billk at iinet.net.au> wrote:
>>>>
>>>>> The VPN is set up for multiple clients in routed mode. I regularly use
>>>>> an android phone and tablet, occasionally a windows desktop and site to
>>>>> site links. I did set up an iPad at one time. Carries ssh, email,
>>>>> calendaring, sip VoIP, security video etc all on private networks. It's all
>>>>> tied together by ospf on the router and various gentoo Linux hosts
>>>>> including the VPN concentrator VM.
>>>>>
>>>>> I also use a stunnel instance in the VM with proxy tunnel and putty on
>>>>> windows to tunnel ssh out of heavily locked down networks. Both openvpn and
>>>>> tunnel listen on public non-standard ports port forwarded through the
>>>>> router. SSL is also port forwarded to an ssl multiplexor in the VM
>>>>> listening on port443 to redirect incoming SSL to either openvpn or stunnel
>>>>> as required, the end points terminate as SSH on my desktop.
>>>>>
>>>>> It sounds complex, isn't really and is quite useful.
>>>>>
>>>>> However what has bothered me about this thread is the emphasis on the
>>>>> router as a problem ... It generally isn't, a router is not automatically
>>>>> compromised so fix that vulnerability first, then attend to real risks.
>>>>> These days you are at far more risk from perverted/subverted mobile devices
>>>>> ... In the scheme of things routers are just one of, and definitely not the
>>>>> main thing you have to worry about.
>>>>>
>>>>> BillK
>>>>>
>>>>>
>>>>> On 22 October 2015 4:25:51 pm AWST, Dirk <
>>>>> justanothergreenguy at gmail.com> wrote:
>>>>>>
>>>>>> 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
>>>>>>> > <mailto:justanothergreenguy at gmail.com>> 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
>>>>>>> >     <mailto:acooks at gmail.com>> wrote:
>>>>>>> >
>>>>>>> >         On Wed, Oct 21, 2015 at 9:43 AM, Dirk
>>>>>>> >         <justanothergreenguy at gmail.com> 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 <mailto:
>>>>>>> plug at plug.org.au>
>>>>>>> >     http://lists.plug.org.au/mailman/listinfo/plug
>>>>>>> >     Committee e-mail: committee at plug.org.au <mailto:
>>>>>>> committee at plug.org.au>
>>>>>>> >     PLUG Membership: http://www.plug.org.au/membership
>>>>>>> >
>>>>>>> > --
>>>>>>> >
>>>>>>> > Kind Regards,
>>>>>>> >
>>>>>>> > /Dean Bergin/.
>>>>>>> >
>>>>>>> >
>>>>>>> >
>>>>>>> > _______________________________________________
>>>>>>> > PLUG discussion list: plug at plug.org.au
>>>>>>> > http://lists.plug.org.au/mailman/listinfo/plug
>>>>>>> > Committee e-mail: committee at plug.org.au
>>>>>>> > PLUG Membership: http://www.plug.org.au/membership
>>>>>>> >
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> PLUG discussion list: plug at plug.org.au
>>>>>>> http://lists.plug.org.au/mailman/listinfo/plug
>>>>>>> Committee e-mail: committee at plug.org.au
>>>>>>> PLUG Membership: http://www.plug.org.au/membership
>>>>>>>
>>>>>> ------------------------------
>>>>>>
>>>>>> PLUG discussion list: plug at plug.org.au
>>>>>> http://lists.plug.org.au/mailman/listinfo/plug
>>>>>> Committee e-mail: committee at plug.org.au
>>>>>> PLUG Membership: http://www.plug.org.au/membership
>>>>>>
>>>>>>
>>>>> --
>>>>> Sent from my Android phone with K-9 Mail. Please excuse my brevity.
>>>>>
>>>>
>>>> _______________________________________________
>>>> PLUG discussion list: plug at plug.org.au
>>>> http://lists.plug.org.au/mailman/listinfo/plug
>>>> Committee e-mail: committee at plug.org.au
>>>> PLUG Membership: http://www.plug.org.au/membership
>>>>
>>>
>>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plug.org.au/pipermail/plug/attachments/20151025/5e68215a/attachment.html>


More information about the plug mailing list