I have seen postings, and heard of cases where people actually assign public IPs to servers sitting in a DMZ behind a firewall. My question is, if you only have one IP block(say a /29), how can you do this? I understand if you either 1-1 NAT or PAT from outside to DMZ, but how can you have an actual public IP on a server behind the DMZ on the ASA, on the same subnet as the outside interface?
"how can you have an actual public IP on a server behind the DMZ on the ASA, on the same subnet as the outside interface?"
You can't unless you run the firewall in transparent mode. When people use public IP's in the DMZ they generally have a separate subnet for the DMZ.
Note you could split your /29 into 2 /30's but you would only 2 addresses then in each subnet.
Not necessarily. They might well have a different subnet for the DMZ ie.
220.127.116.11 255.255.255.252 could be used for the outside.
Your ISP then allocates you another range -
so you could then use this subnet for your DMZ.
But if your ISP only allocates you
you can't have 195.18.18.x address on both the outside interface and on the DMZ.