nsn(8) is a network status monitoring tool. It does listening changes in network configuration using netlink sockets, and prints informative messages  to  console  or  log        file. nsn(8) was written to be used as debug tool with network problems. It can also serve as simple example code for using netlink sockets to listen network changes.         As  of version 0.2 it supports executing command when route/address/interface state changes.