Assessing a network's physical security is an essential step in securing its data. This document describes the design, implementation, and validation of PSATool, a prototype application for assessing the physical security of a network's intermediate distribution frames, or IDFs (a.k.a. "wiring closets"). PSATool was created to address a lack of tools for IDF assessment. It implements a checklist-based protocol for assessing compliance with 52 security requirements compiled from federal and international standards. This checklist can be extended according to organizational needs. PSATool was validated by using it to assess physical security at 135 IDFs at East Tennessee State University. PSATool exposed 95 threats, hazards, and vulnerabilities in 82 IDFs. A control was recommended for each threat, hazard, and vulnerability discovered. The administrators of ETSU's network concluded that PSATool's results agreed with their informal sense of these IDFs' physical security, while providing documented support for improvements to IDF security.