RE: Firewall and DMZ topology

["Depp, Dennis M." <deppdm () ornl gov>]

You are ignoring any intusion detection that should alert you to
nefarious activity inside your DMZ.  This same traffic on the outside of
your firewall may not give concern or alarm, but when it is hitting the
outside interface of your DMZ, alarms should be ringing continuously.  

I do believe if they will be able to break into your second firewall.
The question is will your intrusion detection system alert you they are
breaking in?  If so, you can take action to minize the damage.  This is
why a two firewall system is more secure.

Denis 


-----Original Message-----
From: Daniel B. Cid [mailto:danielcid () yahoo com br] 
Sent: Tuesday, June 10, 2003 4:38 PM
To: security-basics () securityfocus com

Is not that the problem. For example, if you use Linux as your firewall,
and if someone break your first firewall, in most of the cases this
person will be able to break the second too.
why ?
Because in both firewalls you will not run a webserver or a mail server,
but only administrative stuffs, like sshd , telnetd (sux), snmp (bleh)
or other similar. And generally the administrators use the same remote
access program in all firewalls ( and the same password!!) and in all
servers... this is the big problem...
If some security problem appears in some version of the cisco firewall,
and if you use this version in aLL your firewalls... someone will me
able to break all firewalls very easy ...

[]`s

Daniel B. Cid



> On Tue, 2003-06-10 at 16:11, Depp, Dennis M. wrote:
> First in order to increase security Firewall1 should not be the same 
> as  Firewall2.  Even if they are the same, rules will be different on 
> each  of the firewall.  Different rules means different
vulnerabilities.
> Finally Intrusion detection should be more sensative on the inside of

> the outer firewall.  This enhanced sensativity should alert you that  
> someone is attempting to compromize the inner firewall.
>
> Dennis
>
> PS I seriously doubt if two firewalls have the same configuration if 
> one is an internal and one is an external firewall.  For example, on 
> the external firewall I will allow HTTP request to various Web servers

> in the DMZ.  The internal firewall should not allow any internet user 
> to access a web server.
>
>  
>
> > -----Original Message-----
> > From: Daniel B. Cid [mailto:danielcid () yahoo com br]
> > Sent: Tuesday, June 10, 2003 2:47 PM
> > To: Zach Crowell
> > Cc: security-basics () securityfocus com
> >
> > I think similar to you. In most companies all the firewalls are the 
> > same(same OS, same version and same configuration).. If someone is 
> > able to crack the firewall 1, will be able to crack the firewall 2 
> > and 3 ..
> >
> > []`s
> >
> > Daniel B. Cid
> >
> > > On Tue, 2003-06-10 at 13:41, Zach Crowell wrote:
> > >
> > >
> > > Erik Vincent wrote:
> > > > I think there is a major difference between:
> > > >
> > > >               1:    internet --> Outer Firewall --> DMZ -->
Inner 
> > > > Firewall --> LAN
> > > >                            If your Outer Firewall is
> > crack, only the DMZ
> > > > computer will be unprotected
> > > >                             but the LAN portion still protected.
> > >
> > > Under what conditions would these firewalls be configured any 
> > > differently from a vulnerability-assessment view point?  i.e., if 
> > > someone was able to crack the outer firewall, is it not likely 
> > > they would crack the inner firewall as well?
> > >
> > > Zach
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Evaluating SSL VPNs' Consider NEOTERIS, chosen as leader by top analysts!
The Gartner Group just put Neoteris in the top of its Magic Quadrant,
while InStat has confirmed Neoteris as the leader in marketshare.

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Visit us at: http://www.neoteris.com/promos/sf-6-9.htm
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