[mailhist-discuss] Question #2 for my story

Jack Haverty jack at 3kitty.org
Fri Mar 20 16:57:13 PDT 2015


If your story line can put the family's computers on a home LAN, the
scenario you seek was plausible back then.   No need to hack into an
external account, you can do it all on your home LAN.  Perhaps the AOL
account is accessed through the home LAN gateway, using its modem for
dialing in to AOL.   At least that's what would *appear* to be happening.

In the mid/late 80s, we built a piece of software at BBN for internal
use in testing TCP implementations.   The software was an application
that ran in a Sun workstation (simply because it was convenient).   It
could monitor and manipulate the traffic on the attached LAN.   You
could also have written such an app for use in a PC; perhaps someone
did....  It certainly would have been possible by 1994, when it was
pretty common to have LANs connecting multiple computers.

We would test a TCP implementation by configuring that app (we called it
a Flakeway), to intercept all traffic to and from the computer being
tested, and then selectively forward that traffic to its original
destination.   In order to test TCP implementations, the app could be
told to perform various actions that would stress the TCP in the other
computer.  E.G., it could duplicate packets, delay them, corrupt them,
or drop them.  All of these were things that could happen naturally in a
long-distance network path, but were unlikely to occur over a LAN.   The
"Flakeway" made the LAN behave like a long-haul network, which was
useful for evaluating how a TCP implementation would fare in such
situations, but while it was still in a controlled lab environment.

It was a simple extension to have the Flakeway intercept traffic but
forward it on to a different destination.   We also did this for various
tests.  It was also good for the occasional prank - like setting the
office LAN so that a manager's attempts to connect to various computers
on the Internet would instead connect to some other random destination.

With this capability, it would be straightforward to intercept all email
traversing the LAN and do whatever you like with it, even including
changing the contents.   The husband in your story could have easily
created havoc, undetectable unless you were a very experienced network
wizard.

HTH,
/Jack Haverty

PS - for the geeks:   The Flakeway monitored all LAN packets, looking
for ARP handshakes.   When it detected a gateway asking for a
destination IP address's MAC address, it would wait for the real
destination computer to reply with the proper MAC address - its own. 
The Flakeway would then immediately send its own ARP reply, but
containing the appropriate MAC address for the diversion to a different
host.   At that time, computers tended to believe whatever they heard
last, so traffic was effectively diverted until another ARP handshake
occurred.  Repeat.

I wonder if this would still work....it's only been about 30 years...



On 03/20/2015 10:08 AM, Linda Hess wrote:
> To the group members:
>
> I posted a question back in November regarding early use of email. I'm
> writing a novel and didn't want to rely on my memory as the only
> reality check. My question at the time was, how easy would it have
> been for a person (a private user) to go radio-silent on another
> person in 1994. I got some good and useful responses, for which I am
> grateful.
>
> My second question involves the following scenario.
>
> One of my characters, a husband, wants to be sure his wife's emails to
> a cerain person do not get through. He wants it to appear to his wife
> that her correspondent has dropped out of contact completely. 
>
> The year is 1994, and the wife's account is an AOL account (dial-up!).
>
> Does anyone on the list know if it would be possible for someone to
> hack the account and redirect emails to a specific person so they
> don't get through? Or would there be some easier way, like tinkering
> with an email address that someone might not notice but would render
> the email undeliverable?
>
> Or is this just too far-fetched for consideration?
>
> Once again, thank you to all who chose to respond!
>
> Linda Hess
>
>
> _______________________________________________
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> mailhist-discuss at emailhistory.org
> http://emailhistory.org/mailman/listinfo/mailhist-discuss

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