To check if syslog is being received from a network device, which command from the backend is the best?

Using tcpdump is a highly effective method to verify if syslog messages are being received from a network device because it allows you to capture and analyze the network traffic on the specified interface. When you run tcpdump, you can filter the packets by the syslog port, typically UDP port 514, which enables you to see live syslog entries as they come in. This real-time monitoring can help confirm that the syslog server is successfully receiving messages from the network devices.

Other options such as phDeviceTest and phSyslogRecorder serve different specific functions within Fortinet's system and typically do not focus on the raw traffic analysis needed to check incoming syslog messages. Netcat, while capable of generating and sending raw traffic, doesn’t inherently provide the same depth of monitoring capability as tcpdump for verifying the receipt of syslog messages on a network level. Hence, using tcpdump stands out as the most direct and effective approach for checking the reception of syslog data.