Setting up ssl https On Nagios XI Server

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centos linux nagios nagiosxi ssl https monitoring

HTTPS is a protocol for secure communication over a computer network which is widely used on the Internet. HTTPS consists of communication over Hypertext Transfer Protocol (HTTP) within a connection encrypted by Transport Layer Security or its predecessor, Secure Sockets Layer. The main motivation for HTTPS is authentication of the visited website and protection of the privacy and integrity of the exchanged data. Intro Courtesy Wikipedia

Full SSL support requires Nagios XI version 2011R1.6 or later.

Before we start.

Check if the below packages are install, they should be if you are using latest Nagios XI, but check them anyways.

yum install mod_ssl openssl

Creating Key and Certificate

Lets generate the key for the server.

openssl genrsa -out ca.key 2048

Output for the command.

[ahmed@nagiosserver ~]$ openssl genrsa -out ca.key 2048
Generating RSA private key, 2048 bit long modulus
e is 65537 (0x10001)

Now we create the certificate.

openssl req -new -key ca.key -out ca.csr

Here is the output for the command.

[ahmed@nagiosserver ~]$ openssl req -new -key ca.key -out ca.csr
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
Country Name (2 letter code) [XX]:TR
State or Province Name (full name) []:Istanbul
Locality Name (eg, city) [Default City]:Istanbul
Organization Name (eg, company) [Default Company Ltd]:Ahmed, Inc
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []
Email Address []:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

We have not entered anything in the extra attributes, but this is fine.

Checking the certificate.

openssl x509 -req -days 365 -in ca.csr -signkey ca.key -out ca.crt


[ahmed@nagiosserver ~]$ openssl x509 -req -days 365 -in ca.csr -signkey ca.key -out ca.crt
Signature ok
subject=/C=TR/ST=Istanbul/L=Istanbul/O=Ahmed, Inc/
Getting Private key
[ahmed@nagiosserver ~]$

Copy Key/Certificate to Specific Location.

Now we need to copy the certificate files to the correct location and set permissions:

cp ca.crt /etc/pki/tls/certs
cp ca.key ca.csr /etc/pki/tls/private/

Setting permissions.

chmod go-rwx /etc/pki/tls/certs/ca.crt
chmod go-rwx /etc/pki/tls/private/ca.key

Update Apache Configuration

Open the /etc/httpd/conf.d/ssl.conf, find the following lines and update path, this is similar to what we copied earlier.

SSLCertificateFile /etc/pki/tls/certs/ca.crt
SSLCertificateKeyFile /etc/pki/tls/private/ca.key

Here is how the Configuration looks like.

ssl cert

In that same file add the below contents just before </VirtualHost> tag:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule nagiosxi/api/v1/(.*)$ /usr/local/nagiosxi/html/api/v1/index.php?request=$1 [QSA,NC,L]

Here is how a part of the config looks like.


Update httpd.conf Configuration.

Update /etc/httpd/conf/httpd.conf, Add the following lines to the end of the file:

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

Here how the file looks like.

httpd config

Next we restart httpd

sudo service httpd restart


[ahmed@nagiosserver ~]$ sudo service httpd restart
Stopping httpd:                                            [  OK  ]
Starting httpd: httpd: apr_sockaddr_info_get() failed for nagiosserver
httpd: Could not reliably determine the server's fully qualified domain name, using for ServerName [  OK  ]

Now we can go to, you get a warning about self certified certificate, add it to exception and we are ready.

[Important] Now we update Nagios XI Configuration.

  • First update the file.

Here is the path to the file.

[ahmed@nagiosserver ~]# vim /usr/local/nagiosxi/html/

Update the below configuration in the file. (Currently $cfg['use_https'] = false;)

// force http/https
$cfg['use_https'] = true; // determines whether cron jobs and other scripts will force the use of HTTPS instead of HTTP
  • Next logon to Nagios XI server as nagiosadmin.
  • Go to Admin -> on the left pane System Config -> System Settings -> General.
  • Change the URL to https. Change to
  • Next go to Configure on the top tab -> Core Config Manager -> On the left pane Config Manager Admin -> Core Manager Settings -> Change Server Protocol to HTTPS

Restart nagios, httpd.

NOTE : If you are using filewall make sure to add the entry to iptables

iptables -I INPUT -p tcp --dport 443 -j ACCEPT
service iptables save

Now logon to the server.

Written on August 17, 2016