lm_sensors provides essential tools for monitoring the temperatures, voltages, and fans of Linux systems with hardware monitoring devices. It contains a library for sensors access (libsensors), a command-line tool for sensor reporting (sensors), and a daemon (sensord). It also contains scripts for sensor hardware identification and fan speed control.
GKrellM is a GTK-based stacked monitor program that charts SMP CPUs, disks, load, active net interfaces, and internet connections. There are also builtin monitors for memory and swap, file systems with mount/umount feature, mailbox checking including POP3 and IMAP, clock/calendar, laptop battery, sensors (temperatures, voltages, and fans), and uptime. It has LEDs for the net monitors and an on/off button and online timer for PPP. There is a GUI popup for configuration, plugin extensions can be installed, and many themes are available. It also features a client/server monitoring capability.
ntopmg is a network probe that shows network usage in a way similar to what top does for processes. It acts as a Web server, creating an HTML dump of the network status. It sports a flow collector, an HTTP-based client interface for creating ntop-centric monitoring applications, and RRD for persistently storing traffic statistics. Its C++ core can be scripted in Lua, for changing the appearance and extending functionality.
The Advanced Linux Sound Architecture is composed of several parts. The first is a fully modularized sound driver which supports module autoloading, devfs, isapnp autoconfiguration, and gives complete access to analog audio, digital audio, control, mixer, synthesizer, DSP, MIDI, and timer components of audio hardware. It also includes a fully-featured kernel-level sequencer, a full compatibility layer for OSS/Free applications, an object-oriented C library which covers and enhances the ALSA kernel driver functionality for applications (client/server, plugins, PCM sharing/multiplexing, PCM metering, etc.), an interactive configuration program for the driver, and some simple utilities for basic management.
LCDproc is a utility to drive one or more LCD (and LCD-like) devices attached to a host. It is comprised of a server, which uses a modular device driver system to control attached displays, and one or more clients to gather data as appropriate and send screen data to the server. The included client displays a multitude of system statistics (CPU/memory/disk usage, uptime, date and time, temperature, etc.). Multiple clients can connect to the server simultaneously, and clients can set priorities on the screens they provide to influence in what order items are displayed. This facility can also be used to "pop" critical screens (such as an entry from syslog from a log-watching client). All functionality is implemented in userland. Support for many display devices and several platforms (Linux, *BSD, and Solaris at least) is included.
DansGuardian is a Web content filtering proxy that uses Squid to do all the fetching. It filters using multiple methods including, but not limited to, phrase matching, file extension matching, MIME type matching, PICS filtering, and URL/domain blocking. It has the ability to switch off filtering by certain criteria including username, domain name, source IP, etc. The configurable logging produces a log in an easy to read format. It has the option to only log text-based pages, thus significantly reducing redundant information (such as every image on a page).
Performance Co-Pilot (PCP) is a framework and set of services for supporting system-level performance monitoring and performance management. It provides a unifying abstraction for all of the interesting performance data in a system, and allows client applications to easily retrieve and process any subset of that data using a single API. A client-server architecture allows multiple clients to monitor the same host, and a single client to monitor multiple hosts. Archive logging and replay are integrated so that a client application can use the same API to process real-time data from a host or historical data from an archive.
Angst is an active sniffer, based on libpcap and libnet. It dumps into a file the payload of all the TCP packets received on the specified ports. It implements two methods for active sniffing. Angst is able to monitor ARP requests, and after enabling IP forwarding on the local host, it sends ARP replies mapping all IPs to the local MAC address. Also, it can flood the local network with random MAC addresses (like macof), causing switches to send packets to all ports.
procps is a package of utilities which includes ps, vmstat, top, w, skill, snice, pgrep, pkill, free, sysctl, pmap, uptime, and kill. These utilities report what is running, who is logged in, how long the system has been running, and what is using up memory. They can be used to kill processes and change run-time kernel configuration values.