Agents have been deployed to a Windows server on a network.

SolarWinds agents support two communication modes: "Server-Initiated" (Passive) and "Agent-Initiated" (Active). According to theSolarWinds Platform Agent requirements and port information, the direction of communication determines which firewall ports must be open.

When an agent is configured forAgent-Initiated communication(where the agent on the managed node reaches out to the SolarWinds server), it usesTCP port 17778. This port must be open for inbound traffic on the SolarWinds Main Polling Engine or Additional Polling Engine. This mode is highly beneficial for monitoring servers in DMZs or remote sites where the SolarWinds server cannot initiate a connection through the firewall, but the remote node is allowed to communicate back to the primary management network. Port 17777 (Option B) is used for the legacy Orion Information Service, and 17790 (Option D) is used for specific client-to-server messaging in different contexts, but 17778 is the dedicated, encrypted port for agent-initiated data transmission.