gentoo-overlay/net-analyzer/nagios-core/files/99_nagios4.conf

<IfDefine NAGIOS>

  ScriptAlias /nagios/cgi-bin/ /usr/lib/nagios/cgi-bin/
  <Directory "/usr/lib/nagios/cgi-bin/">
    AllowOverride AuthConfig
    Options ExecCGI
    Require all granted
  </Directory>

  Alias /nagios /usr/share/nagios/htdocs
  <Directory "/usr/share/nagios/htdocs">
    AllowOverride AuthConfig
    Require all granted
  </Directory>

</IfDefine>