Workshop

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Here are some examples of service monitoring packages, listed from the primitive to the sublime:
• Sitter (ftp://feldman.org/pub/sitter) A primitive Linux bash script that checks ports using the
Telnet trick and complains to the console when problems are found. This definitely must be
manually reconfigured for your site.
• Netoscope (http://www.basta.com) A Windows utility for checking socket availability of certain
servers. Issues audible alerts or runs a program (such as email) when problems occur.
• IPSentry (http://www.ipsentry.com) A socket-monitoring package that runs under Windows. It
tries whichever IP addresses and sockets you want, as often as you like. It can also page you when
a problem occurs.
• WhatsUp and WhatsUp Gold (http://www.ipswitch.com) This is a graphical network polling
package with paging features. WhatsUp Gold has Web access, SNMP features, and IPX
monitoring, as well. WhatsUp Gold also has the dubious distinction of being quite expensive for a
polling package (close to $1,000 at this writing).
So when do you use “pollsters” rather than SNMP managers? It depends on what you need. In my
experience, only larger shops tend to use the SNMP managers; they tend to be expensive, resource
intensive, and complex to install and maintain.
Of course, SNMP managers also provide you with lots of information. In particular, the SNMP managers
will provide you service-level information—that is, not only will they tell you whether the resource is
“up” but also how fast it responds, how many bytes of resources are left, and so on. This makes SNMP
managers very valuable if you’re looking to optimize your network. SNMP managers are excellent for
keeping long-term track (baselining) of how your network and resources look on a normal day. As you’ll
see in Hour 23, baselining is a very important part of problem determination when, as they say, “The
network is slow!” After all, if you don’t have a sense of how things typically are, how can you tell when
something is out of range? Long-term service-level record keeping is also a way to know—and a way to
show your boss—that everything is operating efficiently and is working properly.
Still, simple network polling packages can be extraordinarily effective, even for large shops, but
particularly for smaller shops. They’re typically inexpensive compared to the costs of deploying even a
modest SNMP installation, and they’re very easy to configure and use. Although most network polling
packages don’t address service-level issues, look for more of them to do so in the future. Of course,
you’ll never have the rich level of information that SNMP provides, but you might not need it. In short, a
polling package is a one-stop application where you can monitor many services easily. Figure 22.3 shows
one of them.