Protocols & networking: Modbus TCP/RTU, IEC 61850, OPC UA, with awareness of IEEE 2030.5 and SunSpec for DER; managed industrial switches and firewalls (Cisco, Fortinet, Palo Alto, Moxa, Tofino), VPN architectures, and data-diode gateways. OT security platforms: Hands-on with a passive monitoring and asset discovery platform (Nozomi, Claroty, Dragos, Tenable OT, Forescout, Cisco Cyber Vision) or open-source equivalents (Zeek, Suricata, Wireshark, Wazuh), plus SIEM/log aggregation, PKI/CA tooling, and a remote access or PAM platform.