{{tag>nagios php debian troubleshooting}}

====== Nagios troubleshooting ======

===== Nagios not working after Debian upgrade? =====
Apache is probably not executing php files properly.
Make sure the apache modules are enabled. Screenshots of error:
Firefox (something probably cached from before)

{{:wiki:screenshots:nagios_php.png|}}

Chrome fresh navigation to page
{{:wiki:screenshots:nagios_php2.png|}}
Run:

  a2enmod php7.3

List of modules that should be enabled
<code>
# apachectl -M

Loaded Modules:
 core_module (static)
 so_module (static)
 watchdog_module (static)
 http_module (static)
 log_config_module (static)
 logio_module (static)
 version_module (static)
 unixd_module (static)
 access_compat_module (shared)
 alias_module (shared)
 auth_basic_module (shared)
 authn_core_module (shared)
 authn_file_module (shared)
 authz_core_module (shared)
 authz_host_module (shared)
 authz_user_module (shared)
 autoindex_module (shared)
 cgi_module (shared)
 cgid_module (shared)
 deflate_module (shared)
 dir_module (shared)
 env_module (shared)
 filter_module (shared)
 mime_module (shared)
 mpm_prefork_module (shared)
 negotiation_module (shared)
 php7_module (shared)
 reqtimeout_module (shared)
 rewrite_module (shared)
 setenvif_module (shared)
 status_module (shared)

</code>

==== Debian 11 ====
  apt install libapache2-mod-php7.4

==== Debian 12 ====

  apt install php8.2-fpm libapache2-mod-php8.2 &&
  a2enmod php8.2 proxy_fcgi setenvif &&
  a2enconf php8.2-fpm

==== Tested on ====
  * Debian 10 (after upgrade from Debian 9)
  * Debian 12 (after upgrade from Debian 10 -> 11)

===== nagiosgraph js problem =====
When accessing graphs in url nagiosdomain.com/nagiosgraph/cgi-bin/showhost.cgi?host=localhost you get an error
  JavaScript is disabled.
  nagiosgraph.js is not installed or wrong version.

The issue could be in rrd filename (///usr/local/nagiosgraph/var/rrd//) encoding the '"' character as "%22" which confuses javascript. Example of filename 
  Check%20www.karl.com___%7C%20isAlreadySelected%28panel%2C%20selectedValue%29%3B%5Cn%20%20%7D%22%20on%20https%3A%2F%2Fwww.karl.com%2Fde%2Fmantel_cod59141927re.html%20%7CRAUVX.rrd

Simply remove the offending file and reload nagios.

==== Tested on ====
   * nagios 4.2.2
   * nagiosgraph 1.5.2
   * Debian GNU/Linux 11 (bullseye)

===== CHECK_NRPE: (ssl_err != 5) Error - Could not complete SSL handshake with <server_ip> =====
Make sure you are using an up to date nrpe plugins.

==== Tested on ====
  * Debian 10 (after upgrade from Debian 9)

===== Cannot get interface speed using highperf mib : UNKNOWN =====
Add to ''check_if_traffic'' -g2 flag:

  check_if_traffic!22!localhost!public!eth0!0,50000!0,75000!-Y -B -k -g2 --label

===== Settings not applied after restart =====

For example if changing whether or not notifications will be sent, nagios by default [[https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/4/en/configmain.html#use_retained_program_state|remembers state]] even after restart, so for [[https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/4/en/configmain.html#enable_notifications|notifications]] you will need to change it manually in ///usr/local/nagios/var/retention.dat//.

You could also remove this file (but first stop nagios and make a backup!) which will force reread of all configs and schedule the check for all hosts and services, so make sure you want this.

===== undefined reference to `get_dh2048' nrpe =====
Happened when trying to make install nrpe version 3.2.0 on Debian 12. Used version nrpe 4.1.0.and problem went away.

===== Cannot write to pidfile '/var/run/nrpe.pid' - check your privileges. =====
Check the pid in nrpe.cfg and the nrpe.service file, The paths should match there.
  ~# grep pid /usr/local/nagios/etc/nrpe.cfg
  pid_file=/var/run/nrpe.pid

<code>
systemctl cat nrpe
# /lib/systemd/system/nrpe.service
[Unit]
Description=Nagios Remote Plugin Executor
Documentation=http://www.nagios.org/documentation
After=var-run.mount nss-lookup.target network.target local-fs.target time-sync.target
Before=getty@tty1.service plymouth-quit.service xdm.service
Conflicts=nrpe.socket

[Install]
WantedBy=multi-user.target

[Service]
Type=simple
Restart=on-abort
PIDFile=/usr/local/nagios/var/nrpe.pid <<--- THIS
</code>

Here the fix was to update the nrpe.cfg with the path from systemd file.

====== See also ======
  * [[wiki:icinga_troubleshooting|Icinga troubleshooting]]
====== References ======
  * https://www.techrepublic.com/article/how-to-fix-apache-2-not-executing-php-files/
  * https://support.nagios.com/forum/viewtopic.php?f=7&t=40351&p=205190#p205190
  * https://serverfault.com/questions/805616/cannot-get-interface-speed-with-standard-mib-use-highperf-mib-g
  * https://nagios.force.com/support/s/article/Understanding-retention-dat-and-modified-attributes-b41690d9?