Free monitoring tool software for linux

Cimon is Perl program wich monitors the load (memory and CPU) on Cisco routers using SNMP, and generates graphics with statistics using rrdtool. Its good for information about your routers health.

It monitors and displays the cpu 5 minutes utilization in percents and free+used Processor memory. The I/O memory(usualy 2 MB) or Fast on high end routers is being monitored too, but there isnt graphic for it. Cimon is good source for information about your routers health. From version 0.2 cimon can do ip accounting using the cisco ip accounting feature.
The logfiles that it generates as the rrd files needed for the graphics are fully compatible with those produced by sasacct (SASs accounting statistics). So you can use its cgi interface also its posibility to generate graphics on demand or on a user defined interval (via crontab and -g option).

Monitoring API project is a multi-user programming interface designed to simplify the development of network monitoring software and allows users to express their monitoring needs in a device-independent way.
The main abstraction provided by MAPI is the network flow. Although flows have been used before in network monitoring systems, MAPI gives flows a first-class status. Applications that uses MAPI can specify what flows or flow statistics they are interested in by applying functions to flows.
A MAPI function can be a BPF filter, string search, packet counter or more advanced like a NetFlow generator. These function will automatically run in hardware if there is support for it on the hardware being used.
MAPI currently supports the following hardware:
- Normal NICs through libpcap
- DAG cards without co-processor
- SCAMPI adapter
Enhancements:
- This release includes support for distributed monitoring, several new MAPI functions, demo applications, and a lot of bugfixes.

Argus Monitoring System software is a system and network monitoring application.
It will monitor nearly anything you ask it to monitor (TCP + UDP applications, IP connectivity, SNMP OIDS, Programs, Databases, etc).
It presents a nice clean, easy to view web interface that will keep both the managers happy (Red Bad. Green Good.) and the techs happy ("Ah! thats what the problem is").
It can send alerts numerous ways (such as via pager) and can automatically escalate if someone falls asleep.
Main features:
- It is open-source available at no charge.
- It has a clean and intuitive web interface.
- The web pages can easily be understood by non-technical people.
- It can generate graphs of what is going on.
- It can monitor network connectivity (Ping test)
- It can monitor TCP/UDP ports
- It can monitor a wide variety of TCP/UDP applications (HTTP, SMTP, RADIUS, ...)
- It can monitor the output or exit code of a program (Program test)
- It can monitor the content of a web page (such as a shopping cart application)
- It can monitor the authoritativeness of a nameserver
- It can monitor SNMP OIDs (such as BGP status, UPS voltage, room temperature, ...)
- It can monitor the results of SQL queries
- It can monitor itself.
- It can be extended to monitor things that the author didnt think of
- It can notify someone (or many people) when something happens
- It can escalate, and notify someone else, if things dont get fixed.
- It can not alarm for known downtime (maintenance overrides)
- It will summarize and rate-limit multiple notifications to prevent paging-floods.
- It keeps historical statistics, for analysis or SLA verification.
- It scales well and can monitor many, many things.
- It can restrict users to viewing only certain items (user "views")
- It can restrict users access to certain features (access control)
- It can support IPv6.
- It can support SNMPv3.
- It can support l10n for your native language.
- It can support redundant multi-server configurations.
Enhancements:
- This release offers improved performance and scalability, adds support for additional tests, and adds support for failover and redundancy.

Remote Monitoring Agent (RMA in short) is an auxiliary application for HostMonitor. Enterprise license for Advanced Host Monitor already includes license for 10 installations of the agent. Holders of a Lite, Standard or Professional licenses may buy an additional license for Remote Monitoring Agent separately.
HostMonitor 4.0+ can monitor remote networks using Remote Monitoring Agents (RMA). RMA is small application that accepts requests from HostMonitor, performs test and provides information about test result back to HostMonitor.
Why you may need RMA? Here are just several reasons:
RMA increases security of the network. When you have to run the tests such as CPU Usage test or Performance Counters tests on a remote Windows system, HostMonitor must be able to log in to that system with administrators privileges. Instead you may now use an agent installed on that remote system. In this case HostMonitor will not have to log on to that system at all. HostMonitor needs just one TCP port to communicate with the RMA agent (by default it uses #1055 port, however you may set an agent to use any other port).
Remote Monitoring Agent is also a very useful tool when you have to monitor two (or many) separated networks (connected through Internet). In this case installing just one instance of RMA behind the firewall in network "A" will allow to monitor entire network "A" using the HostMonitor located in the network "B" with just one open TCP port.
RMA decreases the network traffic. E.g. frequent use of "File Integrity" or "Compare Files" tests in an array of remote systems may apply significant load on the network. The more and the bigger files you test the more traffic increase you get. RMA runs locally and sends only the test results to the HostMonitor thus decreasing the amount of network traffic.
Remote Monitoring Agent simplifies network administration. You no longer need to share local drives/folders to perform tests such as File Integrity, Folder/File Size, File Availability, Count Files, etc
RMA for Linux / BSD / Solaris allows you to perform tests that HostMonitor cannot perform. For example HostMonitor cannot monitor processes that are running on Linux systems. RMA can do that.
Main features:
- All traffic between Remote Monitoring Agents and HostMonitor is encrypted.
- It is possible to customize the list of enabled tests for each of the agents (e.g. living only Count Files and UNC tests only).
- You can restrict incoming TCP connections with the list of acceptable addresses.
- With RMA Manager you may configure, restart and even upgrade agent(s) remotely.

GetMonitor project is a Python XChat script for monitoring DCC file servers requests on sharing channels and IRC servers.

Similar to AutoGet and SDFind scripts, it helps you request files, monitor queues, and search files automatically.

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Enhancements:
- A display bug that occurred when viewing the comments on a device was fixed.

Sleek Monitor is a combination of basic monitors for:
- OS
- KDE
- Kernel
- CPU & cache
- GPU & GPU Temp
- Memory
- Wired & Wireless networks
- battery with time
- date and calendar

Snmp Monitor provides a SNMP router and monitoring alarms.

Snmp Monitor is a Scotty extension to monitor SNMP variables on the net. If there are changes to the routers, etc., it can send you a message on your cellular, by email, or via the screen.