While it does trend tracking, it simply records state changes rather than performance characteristics. It'll show how often a disk space alarm triggered over the past month, but not the actual disk space use over the past month, limiting the feasibility of using NetSaint instead of commercial monitoring tools such as BMC Patrol and CA Unicenter. However, if good, accurate, flexible monitoring is your primary need, NetSaint should be at the top of your evaluation list.
The Multi-Router Traffic Grapher (MRTG) can monitor and graph your network links using Simple Network Management Protocol (SNMP) information from network devices to acquire and plot the information. The output is in the form of HTML code and GIF images, and it can be used for live, continuous monitoring of network traffic. Like NetSaint, it's written to be portable, in C and Perl, and it runs on Unix platforms as well as on NT. Also like NetSaint, it's widely used by administrators who need to know about problems before they happen or at least when they are happening.
MRTG is available for free under the GNU license. Check out the MRTG main site for detailed feature and download information.
For a preview of the power of MRTG, you can check out an example. It doesn't appear to be a live demonstration, but it shows the type of output that MRTG can generate.
Fortunately for the free source community, MRTG uses three other free source libraries to implement its features. Unfortunately for users, you'll have to download and build those other libraries before you can build and use MRTG, and you'll need recent versions of GCC and PERL installed. Luckily, the versions that come with Solaris 8 appear to be recent enough. (See Resources for links to the three libraries.)
Check out the MRTG sidebar for an example of a full build of all the tools.
Use, abuse, and limitations
MRTG is very straightforward. Point
cgfmaker at a SNMP-enabled network device, and it grabs the information from the device, creating a configuration file for MRTG. Config files can also be crafted by hand for more complex needs. The configuration file is then read by MRTG, which reads information from the targets, creates a graph of it, and includes many options for time ranges, intervals, interfaces, ports, and so on.