dhcpalert - a simple script to email someone if a dhcp lease pool hits a
certain threshold.

REQUIREMENTS
- ISC dhcpd
- dhcpd-pools (http://dhcpd-pools.sourceforge.net/)

INSTALL
- install and configure isc-dhcpd and dhcpd-pools (some notes below)
- copy this script to your dhcp server
- configure settings inside dhcpalert.py
- `touch status_file`
- run dhcpd-pools and pipe output to dhcpalert at regular interval (via
cron, for example)

USAGE

dhcpd-pools -c dhcpd.conf -l dhcpd.leases -L 22 -f c | ./dhcpalert.py

NOTES

dhcpalert.py expects output format of CSV and verbosity level of '22' from
dhcpd-pools.  For our case, we were only concerned about Shared Networks,
not specific ranges.  This script should be able to handle ranges but hasn't
been tested in that fashion (the output from dhcpd-pools -L 11 is similar
enough).  If you do not use shared-network defs in your dhcpd.conf, you can
easily create a separate fake dhcpd.conf for dhcpd-pools to parse with the
subnets/pools/ranges you're concerned about.  For our installation, the
monitored pools were fairly static (updated maybe once a year) so maintaining
a separate config wasn't an issue.