The server described in the question is known as a Bastion host. A Bastion host is a special- purpose computer on a network specifically designed and configured to withstand attacks. It is typically placed in a network's demilitarized zone (DMZ) and acts as a proxy server, offering limited services and filtering packets to protect the internal private network from the public network. It is hardened due to its exposure to potential attacks and usually hosts a single application, like a proxy server, while all other services are removed or limited to reduce the threat surface.

The individual who offers formal experienced testimony in court is known as an Expert Witness.
This person is typically engaged due to their specialized knowledge, skills, or experience in a particular field, which is relevant to the case at hand. They provide informed opinions and insights to help the court understand complex matters that are beyond the general knowledge of the layperson. Unlike other witnesses, an expert witness is allowed to offer opinions and draw conclusions based on the facts presented in the case.