I appreciate that it would not be best practice, but would an OPI box be OK if located in a firewall DMZ?
A friend purchased an OPI on my advice; his ISP supplied router/modem will not allow him to open the required ports. Apparently the ISP tech support told him they couldn’t understand why anyone would want to open ports on a firewall…
The router does have the facility to hold one fixed IP in a DMZ. He cannot change ISP due to other services provided.
OPI should be secure enough to survive in a DMZ, however you are right in that it is a tad more secure behind an additional firewall. OPI do come with its own built in firewall that denies access to ports not used by the preloaded services and is otherwise pretty locked down.