Application is the Layer-7 program which is exchanging data through the flow. This is the piece of software that lays closest to the end user. Examples of Applications are Skype, Redis, HTTP, and Bit Torrent. Layer-7 applications are detected by the NTOP opensource Deep Packet Inspection (DPI) engine named nDPI. In case application detection fails, ntopng marks the flow as ‘Unknown’. If the detection succeeds, the application name and an informative icon are shown.Here is a list of possible informative icons:
The lock icon tells that the protocol carries information in a secure way (e.g. via SSL)
The thumb-up icons tells that the protocol is generally not harmfull for network performance
The thumb-down icons tells that the protocol is generally harmfull for network performance
The smile face tells that the protocol is generally used for user entertainment
The yellow triangle indicates a possible problem on the flow. By clicking a flow details it’s possible to see what the reported problem is (e.g. flow with low goodput)
The application name can be clicked to see all hosts generating traffic for the application.