Nagios provides three plugins for monitoring databases:
check_pgsql for PostgreSQL,
check_mysql for MySQL, and
check_oracle for Oracle. The last will not be covered in this book. They all have in common the fact that they can be used both locally and over the network. The latter has the advantage that the plugin in question does not have to be installed on the database server. The disadvantage is that you have to get more deeply involved with the subject of authentication, because configuring a secure local access to the database is somewhat more simple.
For less critical systems, network access by the plugin can be done without a password. To do this, the user
nagios is set up with its own database in the database ...