10. SECURITY IN WIRELESS ADHOC NETWORKS
In this type of network, security is not a single layer issue but a multilayered one. We have focused
on network layer where the possible attacks are most vulnerable. Some of the attacks that we tried to address
are Black hole, Gray hole, Wormhole, Jellyfish attack, Spoofing and Sybil attack. Due to the above mentioned
network layer threats, the transmission of extremely sensitive information via one single path is not advisable
as the information can easily be lost or hacked if the individual path is not fully trusted. To avoid this threat,
sender may want to send multiple copies through multiple disjoint paths. But this increases the risk of
information leakage. Shared cryptography tries to address this concern. Share is a copy of a original data in
which some bits are present and some bits are missing. It transmits different shares of the information via
multiple disjoint paths at different interval of times. It forces the shares received individually to co-operate for
reconstructing the information at the receiving end. This not only reduces the risk of information leakage but
also reduces the chance of several possible network level attacks.
11. ROUTING MECHANISM FOR WIRELESS AD-HOC NETWORKS
Wireless ad-hoc network consisting of nodes equipped with K (KP2) wireless network interfaces. The
same number K of wireless channels out of more than or equal to K candidates is available for wireless
communication. We assign wireless channels to interfaces with no overlap. Without loss of generality, we
number channels and interfaces from 0 to K _ 1, while assigning the same number to the coupled channel and
interface and numbering is the same among nodes. On the best-effort channel, the OLSRv2 with extension for
our proposed mechanism operates for proactive physical routing and bandwidth information dissemination.
Since we focus on the infrastructure deployed in the region, we assume that the network is immobile and static.
At least, the topology is stable and unchanged while a session is active. Nevertheless, condition of wireless
communication can dynamically change by fading or some other environmental effects.
For example, assume that node 1 receives a real-time packet destined to neighboring node 2 with the
destination IP address of 192.168.0.2. If node 1 selects the interface wlan1 to transmit the packet for its
availability, the destination IP address in the packet is changed to 192.168.1.2 accordingly. Then the packet is
sent from node 1 to node 2 on channel.
An example of wireless channel and IP address assignment
When a packet arrives at a logical intermediate node, it is encapsulated with a new IP header indicating the
next logical hop node. In this way, real-time packets traverse a logical path over a network maintained by a
physical routing protocol, OLSRv2