[Ext] Re: Static IP and IP management

Jim Glassford jmglass at iup.edu
Wed Feb 24 15:00:29 UTC 2016


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.


On 2/24/2016 9:16 AM, Bernard Fay wrote:
> I manage a lab where there is about 300-400 IPs assigned to different 
> network equipments, physical and virtual servers.  So IPs might be 
> assigned for a while then equipments removed because not needed 
> anymore, remember this is a lab.  I would like to know which IPs are 
> in used or not.  Equipments removed means IPs not used anymore so we 
> could reuse those IPs.
> I hope I am clear enough
> Thanks,
> On Wed, Feb 24, 2016 at 9:06 AM, Patrick Trapp <ptrapp at nex-tech.com 
> <mailto:ptrapp at nex-tech.com>> wrote:
>     I believe a helpful answer will require some context. You haven't
>     told us what issues you are having with IP management, so it's
>     going to be difficult to identify how static IP's might be beneficial.
>     Are you having a specific issue you wish to address?
>     ------------------------------------------------------------------------
>     *From:* dhcp-users-bounces at lists.isc.org
>     <mailto:dhcp-users-bounces at lists.isc.org>
>     [dhcp-users-bounces at lists.isc.org
>     <mailto:dhcp-users-bounces at lists.isc.org>] on behalf of Bernard
>     Fay [bernard.fay at gmail.com <mailto:bernard.fay at gmail.com>]
>     *Sent:* Wednesday, February 24, 2016 7:39 AM
>     *To:* Users of ISC DHCP
>     *Subject:* Static IP and IP management
>     Hello everyone,
>     I have been told that static IP assignation can help in IP
>     management. Of course, I can know which IPs are assigned by
>     looking in dhcpd.conf.  But after a while an IP might not be used
>     anymore and nothing in dhcpd or bind will tell me if it still in
>     use or not. I have setup a lab to experiment where I have
>     configured dhcpd and bind and I cannot find out how static IP can
>     really help in IP management.
>     Did I miss something somewhere?
>     Thanks,
>     B
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