Well, since service as such is working, I need to transfer configuration from old to new server.
Where are the files
In my old configuration (Nagios 3.2) conf files are in /etc/nagios folder.
If Nagios 4.0.2 is installed as in my previous post, conf files are in : /usr/local/nagios/etc.
Plug-in-s and PL scripts on Nagios 4.0.2 are in /usr/local/nagios/libexec folder.
Which configuration files need to be copied
From /etc/nagios to /usr/local/nagios/etc :
From /var/nagios to /usr/local/nagios/var :
After transfering configuration files, restart the service, and look in /usr/local/nagios/var log!!
Which configuration files need changing
File /usr/local/nagios/etc/nagios.cfg, and what to change in it :
What is missing, and needs to be added
Aside from installing standard plug-in-s, a heap of PL scripts will probably be missing. They can be just copied from old server to the new one (from folder /usr/lib/nagios/plugins) to new, in folder : /usr/local/nagios/libexec.
In the end
After transfering configuration files and theire change, restart the service, and see the command output and log file /usr/local/nagios/var/nagios.log, as well as the debug log /usr/local/nagios/var/nagios.debug!!