Real-time Network Grapher

Overview

The Real-time Network Grapher (RtNG) is a Java applet. RtNG plots a scrolling line-graph from a continuous feed of CSV-style data RtNG is suitable for plotting data which is send at periodic intervals of 0.1s or greater.

CPU Load (using /proc/stat)

The data feed can be either of:

A TCP port
A URL

Both of the above are subject to the normal applet security constraints

RtNG provides a platform-independant way of viewing "live" data on any Java-capable web-browser.

RtNG is specifically for those who want to make their graphs visible to a wider audience, either within their organisation, or on the internet.

The simplicity of the RtNG server software makes it conceivable to use RtNG to monitor security-sensitive or performance-sensitive servers, such as firewalls or web-servers.

See a demonstration of the RtNG applet here

Using the RtNG Applet

The RtNG applet is configured through a number of applet parameters

Using RtNG to monitor a HTTP Server

A simple RtNG setup would consist of:

A html page
The RtNG.jar file, hosted on the same web-server
A CGI-binary or xinetd service to supply the CSV data

Using RtNG to monitor a non-HTTP Server

By using a TCP proxy or a CGI-binary, it is posible to use the RtNG applet to monitor any server on the network, in spite of the applet security constraint

Consideration should be given to the security implications of using this mechanism. ie the server being monitored will have an open TCP port, unless some client IP-restriction is put in place (eg. firewalling).

RtNG monitoring another (non-HTTP) Server

Applet Security Constraints

The security constraint which affects the RtNG applet directly is:

An applet can only open network connections to the web-server that invoked the applet.

This is not as severe as it may sound, because we can use TCP proxies or CGI-binaries to connect to other servers, provided due care is taken with regard to security.

There are other security constraints on applets. These are described fully in Sun's Java Tutorial - "Security Restrictions"

Applet Parameters

The RtNG applet parameters are described in the RtNG User Guide. A general overview of applet parameters is available in Sun's Java Tutorial - "Using the APPLET Tag"

CSV

CSV stands for Comma Separated Values. The RtNG data format requires:

All data values are simple decimal integers
Fields may be separated by a single comma, or one or more spaces, or a combination thereof.

For example, the following are treated as 3 values on each line:

	10,  10  , 5
	-3,1,0
	8   +7 , 6

Currently, any other characters are ignored, but considered as a separator. For forward-compatability, it would be unwise to rely upon this last point.

This project is hosted on