see also nagios xi
tested on focal
requirements
apt install apache2 php php-gd php-imap php-curl libapache2-mod-php # php-mcrypt apt install libxml-libxml-perl libnet-snmp-perl libperl-dev libnumber-format-perl libconfig-inifiles-perl libdatetime-perl libnet-dns-perl apt install libgd-dev libjpeg-dev libpng-dev # libpnglite-dev groupadd nagios useradd --system -s /sbin/nologin -d /var/nagios -g nagios nagios # setgid in da place, we need same group useradd --system -s /sbin/nologin -d /var/nagios -g nagios nagioscmd mkdir /etc/nagios/ # no need to change ownerships, make install-config will handle it more precisely mkdir /var/nagios/
wget https://github.com/NagiosEnterprises/nagioscore/archive/refs/tags/nagios-4.4.6.tar.gz tar xzf nagios-4.4.6.tar.gz cd nagioscore-nagios-4.4.6/ ./configure \ --sysconfdir=/etc/nagios --localstatedir=/var/nagios \ --with-gd-lib --with-gd-inc \ --with-nagios-user=nagios --with-nagios-group=nagios \ --with-command-user=nagioscmd --with-command-group=nagioscmd \ --with-httpd-conf=/etc/apache2/sites-enabled \ --with-mail=/usr/sbin/sendmail echo $MAKEFLAGS make all make install make install-init make install-commandmode make install-config make install-webconf a2enmod rewrite a2enmod cgi systemctl restart apache2 htpasswd -c /etc/nagios/htpasswd.users nagios ls -lF /etc/nagios/htpasswd.users systemctl restart nagios systemctl status nagios systemctl enable nagios
http://localhost/nagios/
Unable to write to check_result_path ('/var/nagios/spool/checkresults') - Permission denied Failed to init socket '/var/nagios/rw/nagios.qh'. bind() failed: Permission denied
==> nagios and nagioscmd users belong to the same group and those folders are setgid
https://www.howtoforge.com/tutorial/how-to-install-nagios-on-ubuntu-2004/
https://linuxhint.com/install_nagios_ubuntu/
https://linuxize.com/post/how-to-install-nagios-on-ubuntu-20-04/
https://linoxide.com/how-to-install-nagios-on-ubuntu-20-04/
https://www.centlinux.com/2021/04/install-nagios-core-on-ubuntu-lts.html
https://kifarunix.com/install-and-setup-nagios-core-on-ubuntu-20-04/
https://computingforgeeks.com/install-php-mcrypt-extension-on-ubuntu/
https://askubuntu.com/questions/1031921/php-mcrypt-package-missing-in-ubuntu-server-18-04-lts