  The IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) was recently
introduced as the new routing standard for the Internet of Things. Although RPL
defines basic security modes, it remains vulnerable to topological attacks
which facilitate blackholing, interception, and resource exhaustion. We are
concerned with analyzing the corresponding threats and protecting future RPL
deployments from such attacks.
  Our contributions are twofold. First, we analyze the state of the art, in
particular the protective scheme VeRA and present two new rank order attacks as
well as extensions to mitigate them. Second, we derive and evaluate TRAIL, a
generic scheme for topology authentication in RPL. TRAIL solely relies on the
basic assumptions of RPL that (1) the root node serves as a trust anchor and
(2) each node interconnects to the root as part of a hierarchy. Using proper
reachability tests, TRAIL scalably and reliably identifies any topological
attacker without strong cryptographic efforts.
