![\"\"](\"https:\/\/easy-admin.ca\/wp-content\/uploads\/2017\/08\/Nagios.png\")
<\/p>\n<\/p>\n
This section will cover how to install Nagios 4 on your monitoring server. You only need to complete this section once.<\/p>\n
Because we are building Nagios Core from source, we must install a few development libraries that will allow us to complete the build.<\/p>\n
First, install the required packages:<\/p>\n
sudo yum install gcc glibc glibc-common gd gd-devel make net-snmp openssl-devel xinetd unzip\r\n<\/code><\/pre>\nCreate Nagios User and Group<\/h3>\n
We must create a user and group that will run the Nagios process. Create a “nagios” user and “nagcmd” group, then add the user to the group with these commands:<\/p>\n
sudo useradd nagios\r\nsudo groupadd nagcmd\r\nsudo usermod -a -G nagcmd nagios\r\n<\/code><\/pre>\nLet’s install Nagios now.<\/p>\n
Install Nagios Core<\/h3>\n
Download the source code for the latest stable release of Nagios Core. Go to the Nagios downloads page<\/a>, and click the Skip to download<\/strong> link below the form. Copy the link address for the latest stable release so you can download it to your Nagios server.<\/p>\nAt the time of this writing, the latest stable release is Nagios 4.1.1. Download it to your home directory with curl:<\/p>\n
cd ~\r\ncurl -L -O https:\/\/assets.nagios.com\/downloads\/nagioscore\/releases\/nagios-4.1.1<\/span>.tar.gz\r\n<\/code><\/pre>\nExtract the Nagios archive with this command:<\/p>\n
tar xvf nagios-*.tar.gz\r\n<\/code><\/pre>\nThen change to the extracted directory:<\/p>\n
cd nagios-*<\/span>\r\n<\/code><\/pre>\nBefore building Nagios, we must configure it with this command:<\/p>\n
.\/configure --with-command-group=nagcmd \r\n<\/code><\/pre>\nNow compile Nagios with this command:<\/p>\n
make all\r\n<\/code><\/pre>\nNow we can run these make commands to install Nagios, init scripts, and sample configuration files:<\/p>\n
sudo make install\r\nsudo make install-commandmode\r\nsudo make install-init\r\nsudo make install-config\r\nsudo make install-webconf\r\n<\/code><\/pre>\nIn order to issue external commands via the web interface to Nagios, we must add the web server user, apache<\/code>, to the nagcmd<\/code> group:<\/p>\nsudo usermod -G nagcmd apach<\/code><\/pre>\nInstall Nagios Plugins<\/h3>\n
Find the latest release of Nagios Plugins here: Nagios Plugins Download<\/a>. Copy the link address for the latest version, and copy the link address so you can download it to your Nagios server.<\/p>\nAt the time of this writing, the latest version is Nagios Plugins 2.1.1. Download it to your home directory with curl:<\/p>\n
cd ~\r\ncurl -L -O http:\/\/nagios-plugins.org\/download\/nagios-plugins-2.1.1<\/span>.tar.gz\r\n<\/code><\/pre>\nExtract Nagios Plugins archive with this command:<\/p>\n
tar xvf nagios-plugins-*.tar.gz\r\n<\/code><\/pre>\nThen change to the extracted directory:<\/p>\n
cd nagios-plugins-*\r\n<\/code><\/pre>\nBefore building Nagios Plugins, we must configure it. Use this command:<\/p>\n
.\/configure --with-nagios-user=nagios --with-nagios-group=nagios --with-openssl\r\n<\/code><\/pre>\nNow compile Nagios Plugins with this command:<\/p>\n
make\r\n<\/code><\/pre>\nThen install it with this command:<\/p>\n
sudo make install\r\n<\/code><\/pre>\nInstall NRPE<\/h3>\n
Find the source code for the latest stable release of NRPE at the NRPE downloads page<\/a>. Download the latest version to your Nagios server.<\/p>\nAt the time of this writing, the latest release is 2.15. Download it to your home directory with curl:<\/p>\n
\n- cd ~<\/li>\n
- curl -L -O http:\/\/downloads.sourceforge.net\/project\/nagios\/nrpe-2.x\/nrpe-2.15\/nrpe-2.15<\/span>.tar.gz<\/li>\n<\/ul>\n
Extract the NRPE archive with this command:<\/p>\n
\n- tar xvf nrpe-*.tar.gz<\/li>\n<\/ul>\n
Then change to the extracted directory:<\/p>\n
\n- cd nrpe-*<\/li>\n<\/ul>\n
Configure NRPE with these commands:<\/p>\n
\n- .\/configure –enable-command-args –with-nagios-user=nagios –with-nagios-group=nagios –with-ssl=\/usr\/bin\/openssl –with-ssl-lib=\/usr\/lib\/x86_64-linux-gnu<\/li>\n<\/ul>\n
Now build and install NRPE and its xinetd startup script with these commands:<\/p>\n
\n- make all<\/li>\n
- sudo make install<\/li>\n
- sudo make install-xinetd<\/li>\n
- sudo make install-daemon-config<\/li>\n<\/ul>\n
Open the xinetd startup script in an editor:<\/p>\n
\n- sudo vi \/etc\/xinetd.d\/nrpe<\/li>\n<\/ul>\n
Modify the only_from<\/code> line by adding the private IP address of the your Nagios server to the end (substitute in the actual IP address of your server):<\/p>\nonly_from = 127.0.0.1 10.132.224.168<\/span>\r\n<\/code><\/pre>\nSave and exit. Only the Nagios server will be allowed to communicate with NRPE.<\/p>\n
Restart the xinetd service to start NRPE:<\/p>\n
\n- sudo service xinetd restart<\/li>\n<\/ul>\n
Now that Nagios 4 is installed, we need to configure it.<\/p>\n
<\/div>\nConfigure Nagios<\/h2>\n
Now let’s perform the initial Nagios configuration. You only need to perform this section once, on your Nagios server.<\/p>\n
Organize Nagios Configuration<\/h3>\n
Open the main Nagios configuration file in your favorite text editor. We’ll use vi to edit the file:<\/p>\n
sudo vi \/usr\/local\/nagios\/etc\/nagios.cfg\r\n<\/code><\/pre>\nNow find an uncomment this line by deleting the #<\/code>:<\/p>\n#cfg_dir=\/usr\/local\/nagios\/etc\/servers\r\n<\/code><\/pre>\nSave and exit.<\/p>\n
Now create the directory that will store the configuration file for each server that you will monitor:<\/p>\n
sudo mkdir \/usr\/local\/nagios\/etc\/servers\r\n<\/code><\/pre>\nConfigure Nagios Contacts<\/h3>\n
Open the Nagios contacts configuration in your favorite text editor. We’ll use vi to edit the file:<\/p>\n
sudo vi \/usr\/local\/nagios\/etc\/objects\/contacts.cfg\r\n<\/code><\/pre>\nFind the email directive, and replace its value (the highlighted part) with your own email address:<\/p>\n
email nagios@localhost<\/span> ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******\r\n<\/code><\/pre>\nSave and exit.<\/p>\n
Configure check_nrpe Command<\/h3>\n
Let’s add a new command to our Nagios configuration:<\/p>\n
\n- sudo vi \/usr\/local\/nagios\/etc\/objects\/commands.cfg<\/li>\n<\/ul>\n
Add the following to the end of the file:<\/p>\n
define command{\r\n command_name check_nrpe\r\n command_line $USER1$\/check_nrpe -H $HOSTADDRESS$ -c $ARG1$\r\n}\r\n<\/code><\/pre>\nSave and exit. This allows you to use the check_nrpe<\/code> command in your Nagios service definitions.<\/p>\nConfigure Apache<\/h3>\n
Use htpasswd to create an admin user, called “nagiosadmin”, that can access the Nagios web interface:<\/p>\n
sudo htpasswd -c \/usr\/local\/nagios\/etc\/htpasswd.users nagiosadmin<\/span>\r\n<\/code><\/pre>\nEnter a password at the prompt. Remember this login, as you will need it to access the Nagios web interface.<\/p>\n
Note:<\/strong> If you create a user that is not named “nagiosadmin”, you will need to edit \/usr\/local\/nagios\/etc\/cgi.cfg<\/code> and change all the “nagiosadmin” references to the user you created.
\n<\/span><\/p>\nNagios is ready to be started. Let’s do that, and restart Apache:<\/p>\n
sudo systemctl start nagios.service\r\nsudo systemctl restart httpd.service\r\n<\/code><\/pre>\nTo enable Nagios to start on server boot, run this command:<\/p>\n
sudo chkconfig nagios on\r\n<\/code><\/pre>\nOptional: Restrict Access by IP Address<\/h4>\n
If you want to restrict the IP addresses that can access the Nagios web interface, you will want to edit the Apache configuration file:<\/p>\n
sudo vi \/etc\/httpd\/conf.d\/nagios.conf\r\n<\/code><\/pre>\nFind and comment the following two lines by adding #<\/code> symbols in front of them:<\/p>\nOrder allow,deny\r\nAllow from all\r\n<\/code><\/pre>\nThen uncomment the following lines, by deleting the #<\/code> symbols, and add the IP addresses or ranges (space delimited) that you want to allow to in the Allow from<\/code> line:<\/p>\n# Order deny,allow\r\n# Deny from all\r\n# Allow from 127.0.0.1\r\n<\/code><\/pre>\nAs these lines will appear twice in the configuration file, so you will need to perform these steps once more.<\/p>\n
Save and exit.<\/p>\n
Now start Nagios and restart Apache to put the change into effect:<\/p>\n
sudo systemctl restart nagios.service\r\nsudo systemctl restart httpd.service\r\n<\/code><\/pre>\nNagios is now running, so let’s try and log in.<\/p>\n
<\/div>\nAccessing the Nagios Web Interface<\/h2>\n
Open your favorite web browser, and go to your Nagios server (substitute the IP address or hostname for the highlighted part):<\/p>\n
http:\/\/nagios_server_public_ip<\/span>\/nagios\r\n<\/code><\/pre>\nBecause we configured Apache to use htpasswd, you must enter the login credentials that you created earlier. We used “nagiosadmin” as the username:<\/p>\n
![\"\"](\"https:\/\/easy-admin.ca\/wp-content\/uploads\/2017\/08\/nagios-connection2.png\")
<\/p>\n
After authenticating, you will be see the default Nagios home page. Click on the Hosts<\/strong> link, in the left navigation bar, to see which hosts Nagios is monitoring:<\/p>\n![\"\"](\"https:\/\/easy-admin.ca\/wp-content\/uploads\/2017\/08\/nagios-connection3.png\")
<\/p>\n
As you can see, Nagios is monitoring only “localhost”, or itself.<\/p>\n
Let’s monitor another host with Nagios!<\/p>\n
<\/div>\nMonitor a CentOS 7 Host with NRPE<\/h2>\n
In this section, we’ll show you how to add a new host to Nagios, so it will be monitored. Repeat this section for each CentOS or RHEL server you wish to monitor.<\/p>\n
Note:<\/strong> If you want to monitor an Ubuntu or Debian server, follow the instructions in this link: Monitor an Ubuntu Host with NRPE<\/a>.<\/p>\nOn a server that you want to monitor, install the EPEL repository:<\/p>\n
sudo yum install epel-release\r\n<\/code><\/pre>\nNow install Nagios Plugins and NRPE:<\/p>\n
sudo yum install nrpe nagios-plugins-all\r\n<\/code><\/pre>\nNow, let’s update the NRPE configuration file. Open it in your favorite editor (we’re using vi):<\/p>\n
sudo vi \/etc\/nagios\/nrpe.cfg\r\n<\/code><\/pre>\nFind the allowed_hosts<\/code> directive, and add the private IP address of your Nagios server to the comma-delimited list (substitute it in place of the highlighted example):<\/p>\nallowed_hosts=127.0.0.1,10.132.224.168<\/span>\r\n<\/code><\/pre>\nSave and exit. This configures NRPE to accept requests from your Nagios server, via its private IP address.<\/p>\n
Restart NRPE to put the change into effect:<\/p>\n
sudo systemctl start nrpe.service\r\nsudo systemctl enable nrpe.service\r\n<\/code><\/pre>\nOnce you are done installing and configuring NRPE on the hosts that you want to monitor, you will have to add these hosts to your Nagios server configuration before it will start monitoring them.<\/p>\n
Add Host to Nagios Configuration<\/h3>\n
On your Nagios server, create a new configuration file for each of the remote hosts that you want to monitor in \/usr\/local\/nagios\/etc\/servers\/<\/code>. Replace the highlighted word, “yourhost”, with the name of your host:<\/p>\nsudo vi \/usr\/local\/nagios\/etc\/servers\/yourhost<\/span>.cfg\r\n<\/code><\/pre>\nAdd in the following host definition, replacing the host_name<\/code> value with your remote hostname (“web-1” in the example), the alias<\/code> value with a description of the host, and the address<\/code> value with the private IP address of the remote host:<\/p>\ndefine host {\r\n use linux-server\r\n host_name yourhost<\/span>\r\n alias My first Apache server<\/span>\r\n address 10.132.234.52<\/span>\r\n max_check_attempts 5\r\n check_period 24x7\r\n notification_interval 30\r\n notification_period 24x7\r\n}\r\n<\/code><\/pre>\nWith the configuration file above, Nagios will only monitor if the host is up or down. If this is sufficient for you, save and exit then restart Nagios. If you want to monitor particular services, read on.<\/p>\n
Add any of these service blocks for services you want to monitor. Note that the value of check_command determines what will be monitored, including status threshold values. Here are some examples that you can add to your host’s configuration file:<\/p>\n
Ping:<\/p>\n
define service {\r\n use generic-service\r\n host_name yourhost<\/span>\r\n service_description PING\r\n check_command check_ping!100.0,20%!500.0,60%\r\n}\r\n<\/code><\/pre>\nSSH (notifications_enabled set to 0 disables notifications for a service):<\/p>\n
define service {\r\n use generic-service\r\n host_name yourhost<\/span>\r\n service_description SSH\r\n check_command check_ssh\r\n notifications_enabled 0\r\n}\r\n<\/code><\/pre>\nIf you’re not sure what use generic-service<\/code> means, it is simply inheriting the values of a service template called “generic-service” that is defined by default.<\/p>\nNow save and quit. Reload your Nagios configuration to put any changes into effect:<\/p>\n
sudo systemctl reload nagios.service\r\n<\/code><\/pre>\nOnce you are done configuring Nagios to monitor all of your remote hosts, you should be set. Be sure to access your Nagios web interface, and check out the Services<\/strong> page to see all of your monitored hosts and services:<\/p>\n![\"\"](\"https:\/\/easy-admin.ca\/wp-content\/uploads\/2017\/08\/nagios-connection4.png\")
<\/p>\n
Have fun!<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"Install Nagios 4 This section will cover how to install Nagios 4 on your monitoring server. You only need to complete this section once. Install Build Dependencies Because we are building Nagios Core from source, we must install a few development libraries that will allow us to complete the build. First, install the required packages: … Continue reading How To Install Nagios 4 ! Monitor Your Servers on CentOS 7<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"How To Install Nagios 4 ! Monitor Your Servers on CentOS 7 - HP Server","description":"Install Nagios 4 This section will cover how to install Nagios 4 on your monitoring server. You only need to complete this section once. Install Build Dependenc"},"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1589","post","type-post","status-publish","format-standard","hentry","category-general"],"_links":{"self":[{"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/posts\/1589","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/comments?post=1589"}],"version-history":[{"count":0,"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/posts\/1589\/revisions"}],"wp:attachment":[{"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/media?parent=1589"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/categories?post=1589"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/easy-admin.ca\/index.php\/wp-json\/wp\/v2\/tags?post=1589"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}