ipv6mon - by... SI6 Networks' Address Monitoring Daemon http://www.si6networks.com/tools/ipv6mon/ ipv6mon is a tool meant for monitoring IPv6 address usage on a local network. It is meant to be particularly useful in networks that employ IPv6 Stateless Address Auto-Configuration (as opposed to DHCPv6), where address assignment is decentralized and there is no central server that records which IPv6 addresses have been assigned to which nodes during which period of time. ipv6mon employs active probing to discover IPv6 addresses in use, and determine whether such addresses remain active. This appears to be a Linux version only... Cheers!