Hacking_and_Penetration_Testing_with_Low_Power_Devices

Configuring IEEE 802.15.4 modems
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A single coordinator exists in every network. This coordinator defines the network
and performs various administrative tasks such as assigning addresses. If the
network uses encryption, the coordinator is responsible for informing other nodes
of the details. An XBee Series 2 modem operating as a coordinator must have the
coordinator firmware uploaded. For obvious reasons, a coordinator must be on all
the time.
A router is used to extend the range of a network by relaying packets for nodes
that are too far apart to communicate directly with each other. There is no limit on the
number of routers in any network. Routers are not permitted to sleep. If a router
receives traffic bound for a sleeping node, it will keep the traffic (for a while at least)
to send when the destination rejoins the network. An XBee Series 2 modem operating
as a router must have the router firmware uploaded.
In any sizable network, the majority of nodes will be end devices. End devices
must have a parent device that is either a router or a coordinator. When traffic for an
end device is received by the parent (coordinator or router) and the end device is
sleeping, the parent stores the packets. Unlike coordinators and routers, end devices
may save power by sleeping. An XBee Series 2 modem operating as an end device
must have the end device firmware uploaded.
Many different network topologies are possible with ZigBee devices. For our purposes
in this book, we will stick to a star networks (which can be implemented with
Series 1 modems) and cluster trees. A cluster tree network consists of the coordinator
and one or more routers that form a backbone of sorts with end devices hung off of
the router and coordinator nodes.
Because the coordinator must always be on and is responsible for forming the
network, it makes the most sense to make the command console node the coordinator.
An XBee-PRO Series 2 modem loaded with coordinator firmware should be used
by the command console. Hacking drones can utilize the low-power XBee Series 2
modems loaded with end device firmware in order to save power. One or more XBee-
PRO Series 2 modems loaded with the router firmware should be installed in the network
in appropriate places to relay traffic to and from drones and the command
console.
The routers can be stand-alone (not connected to a BeagleBone) in order to save
power. An XBee-PRO Series 2 modem operating as a router must always be on. On a
busy network, it will draw 295 mA at 3.3 V. A simple battery power pack can be
created for these routers using an LD1117v33 voltage regulator (3.3 V equivalent
of the 7805 we used earlier) and three or more 1.5 V batteries. Three or four D cell
batteries should be able to power a stand-alone router for about two days.
CONFIGURING IEEE 802.15.4 MODEMS
Before they can be used, XBee modems must be configured. Digi provides a free
program, X-CTU, which can be used to configure their XBee modems. Up until
recently, only a Windows version of X-CTU was available. A Mac OSX version