Monitoring Ports with Moniker

Abstract

If you're responsible for administering Internet services like HTTP, POP, and SMTP, one of your daily tasks probably consists of testing these services to make sure they're running. Alternatively, you can simply wait for a user to call and complain that mail isn't working. After all, users are often more than willing to notify you by phone or in person when a service is not working. Still, a little pro-active monitoring is a good thing as long as it doesn't require much effort. Sicking a Perl script on the problem will also reduce the amount of time you spend listening to user babble, which will allow you to focus on the more important things in life; like playing Quake for instance.

I whipped up a little script for the job (less than 100 lines) that allows me to monitor ports on various servers. It's a command line script with a couple switches (port and host) with an alternative switch that allows you to specify an email address to send an alert to if the service test fails. You can automate the process by running it as a cron job (*nix), or with at (Scheduler on NT).

Required Modules

For Moniker to work on your system, you should have a recent version of Perl installed, 5.003 or better. You will also need the following modules installed:

• Mail::Sendmail
• Net::Telnet

• on *nix: perl -MCPAN -e "install Mail::Sendmail"
• on NT/Win95: ppm install --location=http://alma.ch/perl/ppm Mail-Sendmail

• on *nix: perl -MCPAN -e "install Net::Telnet"
• on NT/Win95: ppm install Net-Telnet

Syntax

The usage for moniker is quite simple:

moniker -h host -s service [-e email]

So, to test the Web Mother of Perl Web server, the syntax would be:

moniker -h www.motherofperl.com -s www

And if I wanted an email notification in the event of a failed test, the syntax would be:

moniker -h www.motherofperl.com -s www -e eisen@internet.com

Next, let's take a look at the code. It's short but sweet.

moniker.pl Get source This script allows one to monitor Internet services.