Is that possible to upgrade nagios 3.2.1 to nagios 3.2.3 without altering any changes to the original configurations? I have deployed my nagios in centOS 5.4 machine.
as far as i remeber yes. i think there wre some differences at the 2.x 3.x version change, but nothing later. (and even that change required only a couple of substitutions in the config files)