Table of Contents

1. Challenge

   Configure Nagios to Perform a Check

   1. Create a configuration file.

      sudo touch /usr/local/nagios/etc/objects/Linux-FTP-Server.cfg
      

   2. Edit the configuration file.

      sudo vim /usr/local/nagios/etc/objects/Linux-FTP-Server.cfg
      

   3. Add the following lines to the file. The LINUXCLIENT_IP_ADDRESS can be found on the hands-on lab page. Note that event_handler is disabled at a later step in the video.

      define host {
          use             linux-sever
          host_name       linux-ftp-server
          alias           ftpSrv
          address         LINUXCLIENT_IP_ADDRESS
      }
      
      define hostgroup {
          hostgroup_name      linux-ftp-servers
          alias               linux FTP Servers
          members             linux-ftp-server
      }
      
      define service {
          use                     generic-service
          host_name               linux-ftp-server
          service_description     ftp server check
          check_command           ftp_server_check
          check_interval          1
          max_check_attempts      2
       #   event_handler           restart_ftp_server
      }
      

   4. Save your changes and exit the editor.

   5. Edit the commands configuration file.

      sudo vim /usr/local/nagios/etc/objects/commands.cfg
      

   6. Add the following lines to the file.

      define command {
          command_name        ftp_server_check
          command_line        /usr/local/nagios/libexec/check_ftp -H $HOSTADDRESS$
      }
      
      

   7. Save your changes and exit the editor.

   8. Edit the Nagios configuration file.

      sudo vim /usr/local/nagios/etc/nagios.cfg
      

   9. Add the following lines to the file.

      #My files
      cfg_file=/usr/local/nagios/etc/objects/Linux-FTP-Server.cfg
      

   10. Save your changes and exit the editor.

   11. Check to make sure you don't have any errors.

       sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
       

   12. Restart Nagios.

       sudo systemctl restart nagios
       

2. Challenge

   Configure the Linux Client

   1. In a new terminal, log in to the Linux Client using SSH using the credentials found on the hands-on lab page.

      ssh cloud_user@LINUXCLIENT_IP_ADDRESS
      

   2. Install vsftpd.

      sudo yum install vsftpd
      

   3. Start vsftpd.

      sudo systemctl start vsftpd
      

   4. Verify vsftpd is running.

      sudo systemctl status vsftpd
      

   5. Open a firewall port.

      sudo firewall-cmd --permanent --add-port=21/tcp
      

   6. Reload the firewall.

      sudo firewall-cmd --reload
      

   7. Back in the server terminal, change the user to nagios.

      sudo su nagios
      

   8. Transfer to the nagios directory.

      cd ../nagios
      

   9. Generate a key pair. Press enter for all of the options to create a default pair.

      ssh-keygen
      

   10. Open the key file.

       vim .ssh/id_rsa.pub
       

   11. Select the entire key and copy it.

   12. Exit the editor.

   13. Back in the client terminal, transfer to being the super user.

       sudo su
       

   14. Edit the authorized keys.

       vim /root/.ssh/authorized_keys
       

   15. Paste the key from the server to the end of the file.

   16. Save your changes and exit the editor.

   17. Back in the server terminal, SSH into the client.

       ssh root@LINUXCLIENT_IP_ADDRESS
       

3. Challenge

   Configure the Restart Event Handler

   1. Make sure you are in the server, and then install mlocate.

      sudo yum install mlocate
      

   2. Find the eventhandler directory for Nagios.

      locate -i eventhandler
      

   3. Copy the default Nagios directory for event handlers. This is the base directory.

   4. Edit the commands configuration file.

      sudo vim /usr/local/nagios/etc/objects/commands.cfg
      

   5. Add the following lines to the file. Make sure to paste the directory from the previous steps as the EVENT_HANDLER_DIRECTORY.

      define command {
          command_name        restart_ftp_server
          command_line        EVENT_HANDLER_DIRECTORY/restart_ftp_server.sh $SERVICESTATE$ $HOSTADDRESS$
      }
      

   6. Copy the full path and file name for restart_ftp_server.sh above.

   7. Save your changes and exit the editor.

   8. Create and edit the restart_ftp_server.sh file.

      sudo vim EVENT_HANDLER_DIRECTORY/restart_ftp_server.sh
      

   9. Paste the following text into the file.

      #!/bin/bash
      
      if [[ $1 == "CRITICAL" ]]; then
          ssh root@$2 "systemctl restart vsftpd"
      fi
      

   10. Save your changes and exit the editor.

   11. Change ownership and permissions of the file.

       sudo chown nagios:nagios EVENT_HANDLER_DIRECTORY/restart_ftp_server.sh
       sudo chmod +x EVENT_HANDLER_DIRECTORY/restart_ftp_server.sh
       

   12. Edit the configuration file.

       sudo vim /usr/local/nagios/etc/objects/Linux-FTP-Server.cfg
       

   13. Uncomment the line for event_handler by removing the # character.

   14. Save your changes and exit the editor.

   15. Check to make sure you don't have any errors.

       sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
       

   16. Restart Nagios.

       sudo systemctl restart nagios
       

   17. Verify the status of Nagios.

       sudo systemctrl status nagios
       

   18. Transfer to the client terminal and verify the status of vsftpd.

       systemctl status vsftpd
       

4. Challenge

   Test the Restart Event Handler

   1. Open a browser to the public IP address of the server running Nagios. Use the address SERVER_PUBLIC_IP/nagios.

   2. Log in with the username "nagiosadmin" and the password "BlaBla321", without quotes.

   3. Click on Services from the left-hand menu.

   4. In the server terminal, check the log file.

      sudo tail -f /var/log/messages
      

   5. Do the same thing in the client terminal.

      sudo tail -f /var/log/messages
      

   6. Exit the log reporting.

   7. Stop vsftpd.

      sudo systemctl stop vsftpd
      

   8. Verify vsftpd was stopped.

      sudo tail -f /var/log/messages
      

   9. Wait and watch the logs. Verify that the client is eventually restarted.