The excellent open-source monitoring
software Nagios is set up to use plugins to do the actual work of checking services. Here are
some useful plugins from the official
plugin site and an unofficial
aptsoftware updates. The main advantage
cron-aptis that you can centralize your package monitoring: easier to refer to, and more obvious if a machine is missing.
The most useful aspect of this is the
-Doption, which warns
when your jabber server certificate is close to expiring. Command-line
options mean you can fine-tune what you send to the server and what
you expect back.
By default this will check the local
database anonymously. You can specify username, hostname, and so on, but
be warned: Any password will be sent clear-text! A very useful feature is
the ability to check whether the slave server is keeping up with the master
- check_krb5 (homepage): Keep tabs
on your Kerberos server. The plugin takes
hostname, realm, principal and keytab options, so is appropriately secure.
- check_ldap: Will check ldaps as well as ldap, but you do have to provide a login ID
and password in plaintext, or just check anonymous bind.
More generally: Roll your own quickly with check_generic (homepage).
This lets you define a command and a set of expectations/thresholds for the return data, thus saving you much of the work involved in writing a plugin. The homepage has thorough documentation and examples.
This article was first published on ServerWatch.com.