Security Basics: RE: Down with DHCP!!!!

["Andrew Aris" <andrew () dev bigfishinternet co uk>]

The idea of a database of hardware versus IP address is a good one as its a
first port of call when building an idea of what is going on in the network.


Surely however as opposed to manually configuring each device in situ a
better idea would be to control address assignment at the DHCP level -
perform address reservation and make the licences non-expiring. This way you
get the benefits of both approaches. As long as you ensure that the
available range is matched to the "known" list then you wont have the
problems of unauthorised devices getting an address.

cheers,

Andrew


> -----Original Message-----
> From: gigabit () satx rr com [mailto:gigabit () satx rr com] 
> Sent: 17 February 2006 18:31
> To: security-basics () securityfocus com
> Subject: Down with DHCP!!!!
>
> ok, some background...
>
> i have transfered from network engineering to the information 
> security group for my company, which is mid-sized with about 
> 2000 employees across 90 locations (financial).
>
> the lessons learned from being in network engineering is that 
> they are first and foremost concerned with maintaining the 
> production environment.  the management processes/procedures 
> are completely disregarded if it is deemed necessary to "get 
> something done".
>
> as i try to build out a security plan for how to deal with 
> servers/routers/end users, i keep coming to the conclusion 
> that it will be meaningless unless control can be taken over 
> what the other department is doing (network engineering).  
> the one commonality for all devices on the network is that 
> they have an IP address.
>
> i would like to propose to management that dhcp should be 
> disabled, so as to force the building of a database that will 
> hold all of the information needed to begin a comprehensive 
> security policy.  the security group would manage the 
> database to ensure that we are collecting information (such 
> as O/S, IOS version, anti-virus
> compliance...)
>
> i realize this will incur more work for those poor souls that 
> have to deploy hardware, but i believe the benefits out-weigh 
> the costs.  the benefits i see:
>
> 1.  once a branch location is staticly addressed, we have a 
> working inventory of what is out there.
>
> 2.  a more secure environment.  no longer can users bring in 
> non- company owned devices and place them on our production 
> network (which is already a policy---that isn't policed).
>
> 3.  i can setup automated scripts that check MAC addresses to 
> IP addresses on the router ARP tables to check for spoofing.
>
> our branch locations don't change very often.....some are 
> still on token ring for god's sake, so i don't really see 
> that much more workload.
>
> Has anyone else dropped DHCP as a management/compliance decision?
>
> thanks.
>
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---------------------------------------------------------------------------
EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE
The Norwich University program offers unparalleled Infosec management 
education and the case study affords you unmatched consulting experience. 
Tailor your education to your own professional goals with degree 
customizations including Emergency Management, Business Continuity Planning, 
Computer Emergency Response Teams, and Digital Investigations. 

http://www.msia.norwich.edu/secfocus
---------------------------------------------------------------------------