Bob wrote:
I've been thinking about a similar problem& what I'd like to do
would possibly require the DHCP server use a database back-end
instead of a flat file.
I am sure you mean a relational database. The ISC dhcpd already has a
database on the back end. It just isn't a relational database. The
flat-file you are referring to is simply a text dump of the in memory
database. It provides persistent data for the database across
restarts.
I am not sure using a full relational database would improve things.
Does it really need that heavy of a back end? There have been patches
available in the past to add a relational database to it however.
What I would like is for it to automatically give each new client an
IP address and then enter that address as a static entry, every time
a known client requests an IP address it would update a "last seen"
field so that if it runs out of address space it would overwrite the
MAC address of the entry with the oldest "last seen" field.
You have pretty closely described how the ISC DHCP daemon is currently
implemented. It already keeps track of the state of each ethernet
address seen and the times for the lease. It will keep the same
assignment for the same address unless it needs to reclaim it for a
different device.
Please be careful when using words like "static" in your description.
Because strictly speaking your description didn't describe a static
entry. And that word already has the meaning of an address that can't
be changed or overwritten as you say.