hello

how did you deploy your centreon setup? if you used an ova/ovf from centreon or the “installation from package” (a script that will configure centreon with a nice unattended script)

for the postfix problem : postfix is not installed by default, as this is only needed if you want to do mail notification, you need to install and enable that on your machine (yum install postfix, or apt install something, depends on you linux os)

if you don’t need mail notification, simply disable that check-process “proc-postfix” from the list of services in the configuration

for the second issue is a mysql problem, ‘connection-time’ is a mysql check that needs a login/password

this is setup in the “host” configuration of the machine you want to monitor

the host with mysql should have a template that creates a few macro you need to setup for each host

macro like 

or 

(these macro are created in the host automatically if your host has a “mysql” template, or the “app-monitoring-centreon-database-custom” template for example

you do not need to create a macro, but you need to input the correct value on the right)

for the self-check of centreon the login you should input is “centreon”, and the password you generated during the setup of the platform for the DB,

most check will need something to be setup to work, be it a snmp community, a login/password for the thing you want to monitor.

if you don’t specify the correct values for your host, or leave things empty, it will try to use the user running the check on the poller, and that user is “centreon-engine”

each check and their macros are documented on the plugin documentation pages, for example : MySQL/MariaDB | Centreon Documentation (and the section about the macro MySQL/MariaDB | Centreon Documentation )

if it is your first centreon platform, I highly suggest reading how it works 

Basic principles of monitoring | Centreon Documentation

(and reading the multiple pages around that link)