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=OPS635 Lab 51: Nagios Installation and Configuration=

In an enterprise environment, a production server must be staged before deployment. Any upgrade to the production servers must be tested in a testing environment and signed off by the change manager(s) before deploying to the production environment. In this lab, you will install and configure the Nagios monitoring framework on a VM running on your testing environment before deploying it to the production environment. You will use many of the common definitions encountered in a typical nagios installation.==Investigation 1: Manual Minimal Nagios InstallationResources==

* Configure your Nagios to also use any definitions you include in a file called lab1.cfg.* Using the lab1.cfg file, create definitions to get your nagios installation to monitor the following hosts/services:** Create a hostdefinition to make the nagios machine monitor itself (using a non-loopback address). It should use the check_ping command every ten minutes to make sure it is active.** Create a service definition to make the nagios machine monitor whether it can connect to it's)/own ssh service(susing the non-loopback address):. It should use the pre-written check_ssh command every 30 minutes, re-checking every 10 minutes if the initial check fails. ** Seneca Create a timeperiod definition, and set it to only include the days and times you are in OPS635. Modify the definitions in lab1.cfg to only run during this time.* Make sure the webservice running on your nagios machine is accessible from your host(s)/Service(s)machine.* Access the nagios web console and confirm that these checks are working before continuing. ==Investigation 2:Nagios Notifications==*Turn flap detection off for the checks you created in investigation 1.*scsModify the lab1.senecaccfg file to include a contact named after yourself, using your email address in your domain.on Set its notification periods to use the same timeperiod you created in investigation 1.ca*Create a second contact called senioradmin, using the email account for root@<yourdomain>.ops.*ictSet the notification interval for the host and service you created in investigation 1 to five minutes.senecacollege This is unreasonably short for most installations, but in this lab we want to get multiple notifications in a very short time line so that we can be sure they are working.ca*If either of these services go into a hard-fail state, nagios should now send you an email. Note that you will have to configure the email server on your host to accept email for your domain.* Manipulate you machine to cause these checks to fail (e.g. set your firewall to block ssh traffic), and make sure you receive the email before continuing.* Fix your machine so the checks are passing again.* Add a hostescalation and a serviceescalation so that if you don't fix the issue before you are notified three times, the notification will instead be sent to the senior admin.* Cause the checks to fail again, and wait for the notification to be sent to root. ==Investigation 3: Nagios Custom Commands==* Create a script plugin called check_sshd that will use systemctl to check the state of your sshd service. If the service is running, return 0. If it is inactive, return 1. If it is failed, return 2. For any other result return 3.* Create a command definition called check_sshd_status that will call the check_sshd plugin.* Create a new service definition that will use the new command to check the status of your sshd service every two minutes, going into a hard-fail state on the third failed check.* Create an event handler script to restart sshd if it is inactive. Use the nagios macros to make sure it only tries to restart the service on the second failed check (that is, before it goes into a hard-fail state).* Add notifications similar to those for your other checks (you should be notified if the service goes into a hard-fail state, and the senior admin should be notified if you don't fix it). ==Investigation 4: Scripted Nagios InstallationRemote Commands==* Clone your existing VM again. Call the new VM nagiosclonenagiosnrpe.<yourdomain>.ops, and provide it a static address of your choice, and add it to your DNS server.* Install NRPE on nagiosnrpe.* It is not necessary Make sure to modify the NRPE configuration on nagiosnrpe to allow your nagios server to contact it.* Copy your check_sshd plugin to nagiosnrpe, making sure the user account for nrpe can run it. Note you will have to add negotiate this machine with sudo and selinux.* Add a command to your DNS nrpe configuration to allow remote execution of check_sshd.* Start and enable the service, and allow traffic to it through your firewall.* Write Back on your nagios server, add a new host definition for nagiosnrpe, and add a script service that uses nrpe to automate run the nagios configuration process you used in Investigation 1check_sshd plugin on nagiosnrpe.* Test Ensure that the script check runs correctly, then do something to intentionally make it fail (e.g. stop the sshd service), and ensure it will automatically configure a newly installed machine as a nagios serverthat that gets recorded too. 

Demonstrate Upload your lab1.cfg, the nagios configuration from nagiosnrpe, your check_sshd plugin, and your event handler to blackboard. ==Completing The Lab==You have now gained experience using common elements of nagios to monitor machines in your script working network. You have configured hosts that should be monitored, identified services to monitor on a newly installed VMthem, created contacts and notifications so that administrators will be notified when things to wrong (and senior admins can be notified if they don't get fixed), and upload it used nrpe to blackboardallow checks to be performed remotely. You have also written simple checks to customize what you want monitored, and event handlers so that nagios can try to repair simple issues for you. There is still more to learn (host and service groups and dependencies will make your configuration much more efficient), but there is only so much room in the course. With what we have covered you have the basic building blocks to monitor your network.