RE: Using DHCP (was RE: IP Spoofing)

["Safier, Adam (GEIS)" <Adam.Safier () geis ge com>]

What if I know the IP address range of the special group and hard code it
into my PC?  This seems like a fancy way of filtering by IP address only,
with all the old spoofing vulnerabilities.  What am I missing that makes
this truly secure?

Adam

-----Original Message-----
From: Bill_Royds () pch gc ca [mailto:Bill_Royds () pch gc ca]
Sent: Thursday, October 07, 1999 12:45 PM
To: Dave Gillett
Cc: firewall-wizards () lists nfr net
Subject: Re: Using DHCP (was RE: IP Spoofing)


Scenario.
I have a firewall rule set that allows use of a particular service for a
limited
range of IP addresses (192.16.24.16/28 say) . I set up my DHCP server to
give
out this range only to users that validate themselves (basically this range
is
for a logical subnet withing a physical segment). So rather than changing
firewall rules each time a member of that secure user set changes, the DHCP
server validates users by things like NT group or challenge response etc.
This
localizes the
security control to the actual owners of secure service.




"Dave Gillett" <dgillett () deepforest org> on 06/10/99 12:44:13 PM

Please respond to "Dave Gillett" <dgillett () deepforest org>

To:   firewall-wizards () lists nfr net
cc:    (bcc: Bill Royds/HullOttawa/PCH/CA)
Subject:  Re: Using DHCP (was RE: IP Spoofing)



On 3 Oct 99, at 11:01, Bill_Royds () pch gc ca wrote:

> .... Having an authorizing DHCP server that can give the firewall
> lists of IP's that have validated themselves for a service means
> that the list is only as old as the DHCP lease.

  DHCP hands out addresses, but where does it do validation for
*services*?  This is news to me!

David G