Cisco D9824 Installation And Configuration Manual page 92

Chapter 4 Front Panel Operation
3 All other connections that are not specifically requested by remote access
protocol selection or triggered by user actions, such as an FTP transfer, do not
have active listeners and the corresponding TCP/UDP ports are closed. To
strengthen security, the hardware firewall drops all incoming packets for the
closed ports.
Note: The hardware firewall may impose different rules for the Management
and Data ports. For example, remote access protocols, such as SSH or HTTP, are
only enabled on the Management port.
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