Security Basics mailing list archives
RE: DMZ - Question
From: "David Gillett" <gillettdavid () fhda edu>
Date: Fri, 26 Oct 2007 11:51:21 -0700
I am working with 2 pix firewalls, and I am hoping to change FW-2 to a different brand that has stateful inspection.
Are you saying that you don't think the PIX is stateful? I'm absolutely certain that it is. However, you are correct that the only way to make this sort of two-firewall design more secure than a single-firewall design (with three interfaces: Internet, LAN and DMZ) is to use different products for the two firewalls so the defects of one are not duplicated by the other.
One of my questions is the DMZ is in a /24 subnet and the LAN is on a /16 subnet. Is the only way for the web server in the DMZ to communicate with the inside LAN by NATting in the FW-2. Isn't this creating a double subnet from the outside??
No. Assuming that these are public addresses, the /16 is broadcast as a summary route, and the /24 is only visible locally. (I strongly suspect, however, that if you're using a /16, it's probably on a private (RFC1918) range, and so will not be advertised at all.) David Gillett
-----Original Message----- From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of hol64 () hotmail com Sent: Friday, October 26, 2007 8:41 AM To: security-basics () securityfocus com Subject: DMZ - Question I have to setup a DMZ on our network. Our current layout is Internet Router <--> Firewall <--> WAN/LAN Router <--> Servers The idea is to setup a back-to-back DMZ or Dual Firewall DMZ. So the topology would be like this.. Internet Router --> FW-1 <--> DMZ <--> FW-2 <--> WAN/LAN router. On the DMZ we will have a Web Server that needs access back to the Mainframe on the LAN, and a Mail server that need access to another mail server on the LAN. One of my questions is the DMZ is in a /24 subnet and the LAN is on a /16 subnet. Is the only way for the web server in the DMZ to communicate with the inside LAN by NATting in the FW-2. Isn't this creating a double subnet from the outside?? I am working with 2 pix firewalls, and I am hoping to change FW-2 to a different brand that has stateful inspection. Please Advice, Thanks, Pablo
Current thread:
- DMZ - Question hol64 (Oct 26)
- Re: DMZ - Question Ansgar -59cobalt- Wiechers (Oct 26)
- Re: DMZ - Question Daniel Anderson (Oct 29)
- Re: DMZ - Question Ansgar -59cobalt- Wiechers (Oct 29)
- Message not available
- Message not available
- Re: DMZ - Question kevin fielder (Oct 31)
- Re: DMZ - Question Daniel Anderson (Oct 29)
- Re: DMZ - Question Ansgar -59cobalt- Wiechers (Oct 26)
- <Possible follow-ups>
- Re: Re: DMZ - Question hol64 (Oct 26)
- Re: DMZ - Question Ansgar -59cobalt- Wiechers (Oct 29)