s7scan is a tool written in Python that scans networks, enumerates Siemens PLCs, and gathers basic information about them, such as PLC firmware and hardware version, network configuration, and security parameters. It uses the S7 protocol to connect to PLCs, specifically performing 'Read SZL' requests to obtain controller information. The tool can identify active PLCs, retrieve details like PLC type, software and hardware versions, protection settings, and network configuration. It supports both TCP/IP and LLC transport protocols and can be built as a stand-alone binary with pyinstaller. s7scan is based on the 'plcscan' utility by Dmitry Efanov (Positive Research).