the neighbor discovery protocol monitor (ndpmon) is a diagnostic software application used by network administrators for monitoring icmpv6 packets in internet protocol version 6 (ipv6) networks. ndpmon observes the local network for anomalies in the function of nodes using neighbor discovery protocol (ndp) messages, especially during the stateless address autoconfiguration. when an ndp message is flagged, it notifies the administrator by writing to the syslog or by sending an email report. it may also execute a user-defined script. for ipv6, ndpmon is an equivalent of arpwatch for ipv4, and has similar basic features with added attacks detection.