Nagios Support Forum

Hi all,

after upgrade to 2024R1.2.2 i have encountered strange issues. The first one is "Invalid Host Header" prompt after accessing web GUI - the same if I enter URL with host name, FQDN or alias (CNAME), only if I enter IP address the GUI works. The solution I found was to comment out two lines in /usr/local/nagiosxi/html/includes/utils.inc.php:

echo _("Invalid Host Header");
exit();

Then I can enter Nagios XI web interface, but the web pages like hosts, services and so on load forever and do not show at the and.

How to fix it?

OK, seems I have solved the problem - in case somebody encounters something similar - make sure that You have a proper value set in the database:

SELECT * FROM nagiosxi.xi_options WHERE name LIKE "url";

Hi @Nagiusz,

For additional context on your issue, take a look at this thread. Your issue is being caused by new security measures in this release aimed at preventing host header injection attacks. Your host value must be your IP address, localhost, or a name configured as your external url (System Settings -> General).

Let us know if you have any other questions.

Thank you!