Diagnostics, monitoring of processes, network connections on the server and in local network.
HTOP is an advanced process monitor, written for Linux. It was intended to replace the standard top program. Htop shows a dynamic list of system processes, the list is typically justified on the CPU. Unlike top, htop shows all processes in the system. Also shows uptime, CPU usage and memory. Htop is often used in cases where the information given by the utility top is not enough, for example when searching for memory leaks in processes.
NLOAD - a console application which monitors network traffic in real time, and outputs the data channel load in the form of a drawing separately for inbound and outbound traffic. It also provides additional info like total amount of transferred data, the minimum and maximum bandwidth, etc.
FTOP is a tool for monitoring real-time network bandwidth via the command line. IFTOP shows a real time updated list of network connections based on their network usage ordered on every 2 seconds on average, 10 and 40