Educause Security Discussion
mailing list archives
Results: Public vs. Private IP Address Survey
From: "Carr, Michael G" <michael.carr () UKY EDU>
Date: Mon, 8 Oct 2012 20:13:04 +0000
In late August, I developed a simple SurveyMonkey and asked a few questions about Private vs. Public IP Addresses (to
see if any consistent thread could be gleaned.) The responses follow:
Question 5 - If you have any College/Dept IT Mgrs, faculty or researchers who have insisted on keeping/maintaining
public IP addresses, what were their reasons?
* No one has kept public IP addresses. All are NAT'd or PAT'd and managed by central IT.
* Only our public facing servers have global IPs, reachable only from outside. Even such servers have private
internal addresses for campus access.
* They have had no need to ask. Private addresses are only used for our wireless network and special purpose
sensitive networks such as point-of-sale, physical security infrastructure, and back-end servers in the data centers.
* We have no issue with anyone keeping public IP addresses. We do not depend on RFC1918 addresses as a security
layer. Perimeters are established via other mechanisms. We are deploying network virtualization for some administrative
nets where units wish to have a more corporate-style network posture.
* Note that 0% of internal machines have public IPs (i.e., static external IP setup on machine via Nat0) however
we do NAT addresses out and we do have 1 for 1 statics on certain vlans so that we can track malicious activity. We
know it is common practice for allot of colleges/universities to have Nat0 or no firewall(god forbid) but we feel every
layer we can add is an extra boundry that can protect us. Transparency is important when it comes to accountability and
as we move toward IPV6 we will see how important it really is. Hope this helps!
* they have them and we never ask them to give them up.. everyone is on a public IP.. BUT they are not open
inbound from the internet. except tcp port by port basis after full security audits. I only have about 100 addresses
with inbound rules. on all of campus.
* We use private addresses only when application/device security needs demand it.
* Your premise that central IT is coaxing, cajoling or coercing our users to not have public IP addresses
doesn't apply to us. We only "require" private IPs on printers and other strictly local devices like PCI-compliant
workstations. Maybe we don't understand the risks/benefits and technology and are fear-based. (usu.edu)
* The only things that have NON-public IP addresses are infrastructure things, e.g., switches, access points,
surveillance cams, etc.
* We have not tried to take them away. We have a Class B and have not ever bothered to renumber everything to a
private IP space. We've talked about it, but honestly, it will probably never happen until we go to IPv6 (and we have
no concrete plan to do that anytime soon either).
* All of our IP addresses are currently public.
* We have central IT, so there aren't College/Dept IT Mgrs.
Michael G. Carr, JD, CISSP, CIPP
Chief Information Security Officer
The University of Kentucky
122 James F. Hardymon Bldg
Lexington KY 40506-0495
Desk: (859) 218-0306
Mobile: (513) 295-3067
Michael.Carr () UKy edu<mailto:Michael.Carr () UKy edu>
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- Results: Public vs. Private IP Address Survey Carr, Michael G (Oct 08)