Two Internet Connections at Once ... ?

I usually use a Three dongle for secure Internet connections - that is
when logging onto email etc.

And living on the top floor of a block of flats I can also get a free
wifi service from the nearest airport. This is quite useful in that I
can browse the web for free.

However I have noticed that sometimes whilst I am connected via the
Three dongle, the free wifi service also connects.

So in effect I am connected twice to the Internet. When I spot this I
usially disconnect the free wifi 'cos if I'm using my dongle I'm doing
secure stuff like emails, eBay, etc.

When this happens I have checked both connections and they are
transmitting megabytes to and fro.

How is this possible. And which service am I really connected to? And
what are the consequences re: potential hacking into my computer etc.?

Thanks - Chris B.

CJB wrote:
> I usually use a Three dongle for secure Internet connections - that is
> when logging onto email etc.
>
> And living on the top floor of a block of flats I can also get a free
> wifi service from the nearest airport. This is quite useful in that I
> can browse the web for free.
>
> However I have noticed that sometimes whilst I am connected via the
> Three dongle, the free wifi service also connects.
>
> So in effect I am connected twice to the Internet. When I spot this I
> usially disconnect the free wifi 'cos if I'm using my dongle I'm doing
> secure stuff like emails, eBay, etc.
>
> When this happens I have checked both connections and they are
> transmitting megabytes to and fro.
>

I doubt it.

> How is this possible. And which service am I really connected to? And
> what are the consequences re: potential hacking into my computer etc.?
>
> Thanks - Chris B.
>

"CJB" <(E-Mail Removed)> wrote in message
news:a8d602b5-93c7-4ac4-9073-(E-Mail Removed)...
>I usually use a Three dongle for secure Internet connections - that is
> when logging onto email etc.
>
> And living on the top floor of a block of flats I can also get a free
> wifi service from the nearest airport. This is quite useful in that I
> can browse the web for free.
>
> However I have noticed that sometimes whilst I am connected via the
> Three dongle, the free wifi service also connects.
>
> So in effect I am connected twice to the Internet. When I spot this I
> usially disconnect the free wifi 'cos if I'm using my dongle I'm doing
> secure stuff like emails, eBay, etc.
>
> When this happens I have checked both connections and they are
> transmitting megabytes to and fro.
>
> How is this possible. And which service am I really connected to? And
> what are the consequences re: potential hacking into my computer etc.?

You are connected to both. However, one has priority for outgoing traffic.

On a PC, run the command

netstat -rn

This will show all the active routes. The value in the "metric" column
indicates priority. Lower value means higher priority.

Potentially anybody on the public WiFi network can see your computer. If
file sharing is off, ordinarily they should not be able to see any files.
However, being a public WiFi network the operator may have configured the
network so their clients cannot see each other. Ideally you should have a
firewall on your computer, and configure it to prevent access to machines on
the WiFi LAN.

Perhaps the "Three" connection has NAT somewhere, and you are allocated a
private address on the Three network. Alternatively you might be allocated
a public IP address. As with any such connection, you should have a firewall
to protect your computer.

Ideally, you should not run the firewall on your computer. Potentially
malware could corrupt any firewall running on the computer, so you should
place the firewall between your computer(s) and all the internet
connections. This can be done with a router, which will implement NAT
(effectively a firewall function) and - depending on the router - will have
more sophisticated firewall features you can configure.

However, in your circumstances you would require a router that supports the
Three dongle and a WiFi connection. You could implement the WiFi connection
with an Access Point configured as a client. Then choose an ethernet router
with the facility for connecting a USB dongle. Such a router could be
configured for load sharing, so traffic goes out through either or both
connections, depending on the rules you set.

It follows that with this arrangement the internet connections(s) would be
available to all the computers (PC, Mac, Linux - whatever)connected to the
router. Handy if you have several computers.

--
Graham J

Graham J wrote:
> "CJB" <(E-Mail Removed)> wrote in message
> news:a8d602b5-93c7-4ac4-9073-(E-Mail Removed)...
>> I usually use a Three dongle for secure Internet connections - that is
>> when logging onto email etc.
>>
>> And living on the top floor of a block of flats I can also get a free
>> wifi service from the nearest airport. This is quite useful in that I
>> can browse the web for free.
>>
>> However I have noticed that sometimes whilst I am connected via the
>> Three dongle, the free wifi service also connects.
>>
>> So in effect I am connected twice to the Internet. When I spot this I
>> usially disconnect the free wifi 'cos if I'm using my dongle I'm doing
>> secure stuff like emails, eBay, etc.
>>
>> When this happens I have checked both connections and they are
>> transmitting megabytes to and fro.
>>
>> How is this possible. And which service am I really connected to? And
>> what are the consequences re: potential hacking into my computer etc.?
>
> You are connected to both. However, one has priority for outgoing traffic.
>

It ain't that simple.

To successfully load share between two IP addresses - which the PC will
have due to it having two interfaces active - you need to be running BGP.

And no way is a noddy PC on the end of a broadband link going to be
allowed to propagate that.

Even if Microsoft knew what it was..

In reality, if you have two equal weight default routes, half of the
data will go missing as the receiving end will get packets from sources
it doesn't have an active connection to. It can only connect to one IP
address at a time, and if the computer is sending equally via two, it
will be a relative disaster.

I actually had such a customer setup to debug years ago. The exactly 50%
packet loss was the key..

If one interface has preference, then all the traffic, in and out will
go via that route.

The othert may be connected, but will bear only keep-alive traffic.

On Mon, 13 Jun 2011 10:53:35 +0100
The Natural Philosopher <(E-Mail Removed)> wrote:

> CJB wrote:
> > I usually use a Three dongle for secure Internet connections - that
> > is when logging onto email etc.
> >
> > And living on the top floor of a block of flats I can also get a
> > free wifi service from the nearest airport. This is quite useful in
> > that I can browse the web for free.
> >
> > However I have noticed that sometimes whilst I am connected via the
> > Three dongle, the free wifi service also connects.
> >
> > So in effect I am connected twice to the Internet. When I spot this
> > I usially disconnect the free wifi 'cos if I'm using my dongle I'm
> > doing secure stuff like emails, eBay, etc.
> >
> > When this happens I have checked both connections and they are
> > transmitting megabytes to and fro.
> >
>
> I doubt it.
>
I have seen this two-routes effect when I was playing around getting my
wireless system working. I could be connected via WiFi, then plug in
the wired connection, and they would then both be active. I don't know
how much of the total each one did, nor how many IP addresses they had,
but they both showed activity when I opened up the PC's
Connection Information Box, and both used the same modem/router at the
same time.
--
Davey.

On Mon, 13 Jun 2011 13:03:43 +0100, DrTeeth wrote:

> On Mon, 13 Jun 2011 12:29:22 +0100, just as I was about to take a herb,
> The Natural Philosopher <(E-Mail Removed)> disturbed my reverie and
> wrote:
>
>>BGP
>
> What is that please?

Border Gateway Protocol

Regards
Gordon





--
ox·y·mo·ron n. pl. ox·y·mo·ra or ox·y·mo·rons A rhetorical figure in
which incongruous or contradictory terms are combined, as in Microsoft
Security, Microsoft Help and Microsoft Works.

On Mon, 13 Jun 2011 14:05:42 +0000 (UTC), just as I was about to take
a herb, Gordon Darling <(E-Mail Removed)> disturbed my reverie and
wrote:

>Border Gateway Protocol

Thanks Gordon.
--

Cheers,

DrT

** Stress - the condition brought about by having to
** resist the temptation to beat the living daylights
** out of someone who richly deserves it.

DrTeeth wrote:
> On Mon, 13 Jun 2011 12:29:22 +0100, just as I was about to take a
> herb, The Natural Philosopher <(E-Mail Removed)> disturbed my
> reverie and wrote:
>
>> BGP
>
> What is that please?
Border gatey protocol. How internet multipath routing is done.

On Mon, 13 Jun 2011 15:57:32 +0100, just as I was about to take a
herb, The Natural Philosopher <(E-Mail Removed)> disturbed my
reverie and wrote:

>Border gatey protocol. How internet multipath routing is done.

Tnx 2 u 2<g>.
--

Cheers,

DrT

** Stress - the condition brought about by having to
** resist the temptation to beat the living daylights
** out of someone who richly deserves it.

On Mon, 13 Jun 2011 15:58:47 +0100
The Natural Philosopher <(E-Mail Removed)> wrote:

> Davey wrote:
> > On Mon, 13 Jun 2011 10:53:35 +0100
> > The Natural Philosopher <(E-Mail Removed)> wrote:
> >
> >> CJB wrote:
> >>> I usually use a Three dongle for secure Internet connections -
> >>> that is when logging onto email etc.
> >>>
> >>> And living on the top floor of a block of flats I can also get a
> >>> free wifi service from the nearest airport. This is quite useful
> >>> in that I can browse the web for free.
> >>>
> >>> However I have noticed that sometimes whilst I am connected via
> >>> the Three dongle, the free wifi service also connects.
> >>>
> >>> So in effect I am connected twice to the Internet. When I spot
> >>> this I usially disconnect the free wifi 'cos if I'm using my
> >>> dongle I'm doing secure stuff like emails, eBay, etc.
> >>>
> >>> When this happens I have checked both connections and they are
> >>> transmitting megabytes to and fro.
> >>>
> >> I doubt it.
> >>
> > I have seen this two-routes effect when I was playing around
> > getting my wireless system working. I could be connected via WiFi,
> > then plug in the wired connection, and they would then both be
> > active. I don't know how much of the total each one did, nor how
> > many IP addresses they had, but they both showed activity when I
> > opened up the PC's Connection Information Box, and both used the
> > same modem/router at the same time.
>
> the key there is they both used the SAME modem router.
>
>
> so only one public IP address is involved

Makes sense.
--
Davey.