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There is a way to combine both the anonymity of an unlinked network
with the quick response time of the linked approach. This can be
done by employing a technique first envisioned in the description of
a so-called ``Warhol Worm''. While no node knows anything about
other nodes, the network master keeps track of the IPs of infected
hosts. To distribute a command to a couple or maybe all of the
nodes, he first of all prepares an encrypted file containing the IPs
of all active nodes, and combines that with the command to execute.
He then sends this commandfile to the first node on the list. This
node executes the command, takes itself from the list, and goes top
to bottom through the list, until it finds another active node,
which it transmits the command file to. This way each node will only
get to know about other nodes when receiving commandfiles, which are
subsequently erased after the file has been successfully transmitted
to another node. By calling certain nodes by their unique IDs, it's
even possible to make certain nodes take different actions than all
the others. By preparing different files and sending them to
different nodes at start already, quite a fast distribution time can
be achieved. Of course, should someone accomplish to not only sniff
the commandfile, but also decrypt it, he has an entire list of
infected hosts. Someone sniffing a node will still also see an
incoming connection from somewhere, and an outgoing connection to
somewhere else, and thus get to know about 2 more nodes. Thats just
the same as depicted in the passive approach. Whats different is
that a binary analysis of a node will not divulge information on
another host of the network. As sniffing is probably more of a
threat than binary analysis though, and considering a linked network
offers way more flexibility, the Hybrid is most likely an inferior
approach.
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