Transparent mode, in the context of networking and network security, refers to a configuration or operational mode of a network security device or firewall where it operates as an invisible bridge, allowing network traffic to pass through without requiring any changes to the. Transparent mode, in the context of networking and network security, refers to a configuration or operational mode of a network security device or firewall where it operates as an invisible bridge, allowing network traffic to pass through without requiring any changes to the. Transparent mode, in the context of networking and network security, refers to a configuration or operational mode of a network security device or firewall where it operates as an invisible bridge, allowing network traffic to pass through without requiring any changes to the existing network. In the evolving landscape of Operational Technology (OT) cybersecurity, the transparent firewall has emerged as a critical tool for securing industrial environments without disrupting existing network architecture. Also known as stealth, bump-in-the-wire, or layer 2 firewalls, these devices are. This chapter describes how to set the firewall mode to routed or transparent, as well as how the firewall works in each firewall mode. The ASA supports two firewall modes: Routed Firewall mode and Transparent. Transparent firewalls offer several key advantages, primarily centered around network simplicity and enhanced security. The transparent firewall is not a routed hop but instead acts as a bridge by inspecting and moving network frames.