  In this paper, we consider the problem of entanglement verification across
the quantum memories of any two nodes of a quantum network. Its solution can be
a means for detecting (albeit not preventing) the presence of intruders that
have taken full control of a node, either to make a denial-of-service attack or
to reprogram the node. Looking for strategies that only require local
operations and classical communication (LOCC), we propose two entanglement
verification protocols characterized by increasing robustness and efficiency.
