/var/lib/dhcp3/dhcpd.leases
dhcpd leases
Prints active dhcp leases.
dhcp-lease-list [options]
--help
Shows command line help
--parsable
machine readable output with full dates
--last
prints the last (even if end<now) for every MAC
--all
prints all entries i.e. more than one per MAC
dhcp-lease-list shows the dhcpd.leases file but filters, depending on the specified command line options, obsolete entries.
/var/lib/dhcp3/dhcpd.leases
dhcpd leases
/usr/share/misc/oui.txt or /usr/local/etc/oui.txt
optional file to map MAC addresses to manufactorer names
Unchanged in 5 releases since Debian 9 (Stretch).