Which command can help you analyze network bandwidth usage by service?

The command that effectively analyzes network bandwidth usage by service is iftop. This tool provides a real-time view of bandwidth usage on a network interface, allowing you to monitor traffic on a per-connection basis. It displays a list of current network connections and the amount of data being sent and received in real-time, which makes it particularly useful for identifying which services are consuming significant amounts of bandwidth.

Using iftop, you can see data categorized by source and destination IP addresses and ports, making it easier to pinpoint specific services or applications that are heavily utilizing the network. This visualization helps in troubleshooting performance issues or optimizing resource allocation based on the observed usage patterns.

While other commands like netstat can provide information about network connections and their states, and ifstat focuses on overall interface statistics, they do not offer the same level of detail concerning bandwidth usage attributed to specific services in real-time as iftop does. vnstat, on the other hand, collects and displays network traffic statistics over time, but it does not provide real-time analysis of current bandwidth usage per connection. This makes iftop the most suitable choice for analyzing bandwidth usage by service.