Aidan, I have a /29 subnet with a block of public IPs. With the way my firewall is setup there is no less security because I still have to explicitly allow access to tcp/UDP traffic in order to gain connectivity. The big difference is that there are NO NAT rules required. Just pin holes in the linux firewall that sits in front of the actual game server. I don't know of any other way to get the ping going,and believe me I have tried.
Rat buddy, this is like running the server without a router.... Eg plugging a modem into the server and removing the router...but this has some security implications that are better avoided. Depending on how your DMZ is configured, I guess this could work so long as your server has a public ip address assigned to it's NIC and there is no NAT'ing taking place between it and the Internet.
Networking is not my strong point so please excuse me if this is not described with correct technical language. I tend to use trial and error to get the result rather than sitting down and crafting a perfect solution first off.
