[Ext] Re: Static IP and IP management

Michael Ströder michael at stroeder.com
Wed Feb 24 20:44:59 UTC 2016

Bernard Fay wrote:
> This is interesting!  I'll have to find out how to write such scripts.
> Would you have some pointers related to this subject?

Note that anything reyling on MAC addresses will fail with devices which are
frequently changing their MAC address (e.g. modern Android phones).

Ciao, Michael.

> On Wed, Feb 24, 2016 at 10:00 AM, Jim Glassford <jmglass at iup.edu> wrote:
>> Hi,
>> This works for us, ymmv. We use home grown scripts that pull information
>> from a database to build our dhcpd.conf and dns files for all static
>> assignments.  We also have different scripts that pull the arp tables from
>> the routers each hour and from layer two switches ports to keep track of
>> who is where.
>> Put these together to keep some control for IPAM, sure the commercial
>> products do a better job.
>> As part of the hour run script, we do a compare on what is found in arp
>> tables to what we have in the assigned database. If a match, the MAC and IP
>> address match what is in the database, update a count field and the date it
>> was found. If a MAC is found in arp table does not match the assigned IP
>> address, send and email for a discrepancy (someone hard coded when they
>> should not or other issue that needs addressed)
>> Once in awhile (when I need more static IP addresses for a subnet) review
>> the count and last updated fields, if older than a year +/- then safe to
>> re-assign this IP address.
>> best!
>> jim

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