Monitoring Linux Servers
Figure 1 displays the layer model of a Linux server. While the Operating System layer represents the state of the host system on which the application executes, the Network layer represents the state of the network links to and from the host system. Depending on whether the application relies on the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP), either the Tcp or the Udp layers is used to represent the status of the transport protocol. The Application Processes layer tracks the status of key processes executing on the host system.