On 28 Feb 2002, at 17:30, Gustavo Ritondale wrote:

> I have CDN access with 16 ip addresses. (subnet mask 255.255.255.240)
> I need a DMZ for servers and NAT for private LAN.
> I'll use ipchains firewall with 3 NICs. 
> 
> Router = xxx.xxx.xxx.209
> 
> My question is: Should i divide ( split ) my 16 public addresses into 2 subnets ( 
>with subnet mask=255.255.255.248) 
> like         xxx.xxx.xxx.208 - xxx.xxx.xxx.215 
>               xxx.xxx.xxx.216 - xxx.xxx.xxx.223
> or i can leave subnet mask unchanged and install the firewall on xxx.xxx.xxx.210  ??
> 
> Thanks, GLR

  You don't want to split your /28 block into two /29s, because that 
will lose you two more of those valuable public IPs.

  What I would do is put the firewall on .209, and use static NAT 
between .210-.222 and addresses on a private block range used in your 
DMZ.  So all traffic for these addresses coming in via your internet 
router will be passed to the firewall, filtered by its policies, and 
then NATted over to the real servers.

  So the only devices that are actually configured for the 
xxx.xxx.xxx.208/28 network are the untrusted interface of the 
firewall, and the local interface of the internet router.

Dave Gillett



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