Last night I installed Nagios 4 on an Ubuntu 13.10 VM running on my VMWare ESXi machine.
I followed through the steps listed here, which worked overall:
https://raymii.org/s/tutorials/Nagios_Core_4_Installation_on_Ubuntu_12.04.html
I did run into a small number of issues which should be documented for anyone trying this on a later install of Ubuntu, but raymii isn’t allowing comments, so I can’t post them there.
1) The Apache configuration setup changed, (as it did in Debian, breaking a few things) so instead of a conf.d directory, it uses conf-available and conf-enabled, just like mods and sites. Further, the configure script doesn’t pick this up automatically, so you need to tell it where the config directory is (I told it the conf-available directory and then linked from conf-enabled, per the standard as it typically is)
2) The ‘default’ site which they tell you to disable has been renamed, you can “a2dissite 000-default” to remove the site.
3) Most critically, apache doesn’t have CGI enabled automatically. Most importantly was enabling the CGI module and reloading Apache.
Overall Nagios 4 seems to have installed correctly and is running nicely. I'll try to get my configs over from my production system and see how they run and start playing with the new features in version 4.
I’ve also installed Zabbix on another VM, I’ll be doing some more reading and seeing if I can’t duplicate at least some of the checks I have in Nagios into Zabbix and then write up a review comparing them.