Friday, September 17, 2021

Tip of the Trade: Nagios Plugins

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
plugin collection
.

  • check_apt:

    Checks for apt software updates. The main advantage
    over cron-apt is that you can centralize your package monitoring: easier to refer to, and more obvious if a machine is missing.

  • check_jabber:
    The most useful aspect of this is the -D option, 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.

  • check_mysql:
    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
    server.
  • 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.

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