"We are not talking about ANY firewall here, we are talking about ISA...one of the key advantages of ISA is that you can create perimeter networks even for domain members as ISA can perform RPC and other app filtering. Hence you can move domain members that represent more of a security risk away from other domain member servers." We are not talking about ANY firewall here, we are talking about ISA.....Exactly, with the same protection behind it for the domain, so what's the point of the DMZ??? Steve From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Jason Jones Sent: Wednesday, January 10, 2007 8:36 PM To: isapros@xxxxxxxxxxxxx Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks Sorry t - the quote in my last post should have been from you, and not Steve. Thought I was going mad until you posted! Jason Jones | Silversands Limited | Desk: +44 (0)1202 360489 | Mobile: +44 (0)7971 500312 | Fax: +44 (0)1202 360900 | Email: jason.jones@xxxxxxxxxxxxxxxxx <mailto:jason.jones@xxxxxxxxxxxxxxxxx> ________________________________ From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Thor (Hammer of God) Sent: 11 January 2007 00:26 To: isapros@xxxxxxxxxxxxx Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks Because it's safer that way, that's why... That's what an authenticated access DMZ perimeter is for- with a CAS server that presents logon services to any Internet user, I would (and, in fact, require) that the server be in a least-privileged authenticated access perimeter network that limits that servers communications to the minimum required for required functionality - and only to the hosts it needs to talk to. Let's say there is a front-end implementation issue or coding vulnerability: the CAS on the internal network would allow unfettered, full-stack access to the internal network. A CAS in a perimeter DMZ would mitigate potential exposure in the event of a 0day or configuration issue. "Safer on the internal network" is a complete misnomer when it comes to servers presenting services to an untrusted network. t On 1/10/07 3:04 PM, "Jim Harrison" <Jim@xxxxxxxxxxxx> spoketh to all: Why would you want to place a member of your internal domain in your DMZ, fer chrissakes?!? Hosting any domain member in the DMZ is a difficult proposition; especially where NAT is the order of the day. You can either use a network shotgun at your firewall or attempt to use your facvorite VPN tunnel across the firewall to the domain. Jim ________________________________ From: isapros-bounce@xxxxxxxxxxxxx on behalf of Jason Jones Sent: Wed 1/10/2007 2:35 PM To: isapros@xxxxxxxxxxxxx Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks From what I can gather, the new CAS role now uses RPC to communicate with the back-end (not sure of new name!) servers so I am guessing that this is an "RPC isn't safe across firewalls" type stance. Which I guess for a PIX, is a pretty true statement. Just think how much safer the world will be when firewalls can understand dynamic protocols like RPC...maybe one day firewalls will even be able to understand and filter based upon RPC interface...maybe one day... :-D ;-) Shame the Exchange team can't see how much ISA changes the traditional approach to DMZ thinking...kinda makes you think that both teams work for a different company :-( Jason Jones | Silversands Limited | Desk: +44 (0)1202 360489 | Mobile: +44 (0)7971 500312 | Fax: +44 (0)1202 360900 | Email: jason.jones@xxxxxxxxxxxxxxxxx <mailto:jason.jones@xxxxxxxxxxxxxxxxx> <mailto:jason.jones@xxxxxxxxxxxxxxxxx> ________________________________ From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Greg Mulholland Sent: 10 January 2007 22:07 To: isapros@xxxxxxxxxxxxx Subject: [isapros] Re: ISA, Exchange 2007 and Perimeter Networks I seriously hope that they have take different paths and these are not limitations on the software or it is going to mean a nice little redesign and break from custom.. Greg ----- Original Message ----- From: Jason Jones <mailto:Jason.Jones@xxxxxxxxxxxxxxxxx> <mailto:Jason.Jones@xxxxxxxxxxxxxxxxx> To: isapros@xxxxxxxxxxxxx Sent: Thursday, January 11, 2007 8:25 AM Subject: [isapros] ISA, Exchange 2007 and Perimeter Networks Hi All, I heard today from an Exchange MVP colleague that members of the Exchange team (Scott Schnoll) are saying that they (Microsoft) do not support placing the new Exchange 2007 Client Access Server (like the old Exch2k3 FE role) role into a perimeter network. Has anyone else heard the same? This sounds very similar to Exchange admins of old when they didn't really understand modern application firewalls like ISA could do - RPC filter anyone??? http://groups.google.co.uk/group/microsoft.public.exchange.design/browse _thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+isa&rn um=2&hl=en#4db165c21599cf9b <http://groups.google.co.uk/group/microsoft.public.exchange.design/brows e_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+i sa&rnum=2&hl=en#4db165c21599cf9b> <http://groups.google.co.uk/group/microsoft.public.exchange.design/brows e_thread/thread/4ecab9cb8e50015e/4db165c21599cf9b?lnk=st&q=cas+dmz+isa&r num=2&hl=en#4db165c21599cf9b> I have just about managed to convince Exchange colleagues (and customers) of the value of placing Exchange FE servers in a separate security zone from BE servers, DC's etc and now I here this... Are the Exchange team confusing the old traditional DMZ's with what ISA can achieve with perimeter networks? From what I believe, it is good perimeter security practice to place servers which are Internet accessible into different security zones than servers that are purely internal. Therefore, the idea of placing Exchange 2003 FE servers in an ISA auth access perimeter network with Exchange 2003 BE servers on the internal network has always seemed like a good approach. It also follows a good least privilege model. Is this another example of the Exchange and ISA teams following different paths???? Please tell me that I am wrong and that I am not going to have to start putting all Exchange roles, irrespective of security risk, on the same network again!!!! Comments? Cheers JJ All mail to and from this domain is GFI-scanned.