slackbuilds/network/arpwatch

The arpwatch package contains arpwatch and arpsnmp.  Arpwatch and
arpsnmp are both network monitoring tools.  Both utilities monitor
Ethernet or FDDI network traffic and build databases of Ethernet/IP
address pairs, and can report certain changes via email.

Install the arpwatch package if you need networking monitoring devices
which will automatically keep track of the IP addresses on your
network.