nagios service check example

When Nagios needs to run a scheduled service check, it will initiate the service check and then return to doing other work (running host checks, etc). Please note that this article is published by Xmodulo.com under a Creative Commons Attribution-ShareAlike 3.0 Unported License. A user [emailprotected] is created in MySQL server. The __HOST__ is a special service name, which represents the host check in Nagios. Here is an example set of passive checks that . For Nagios, many, many Oracle plugins are available for checking database availability and performance. For example, when a web application cannot connect to the database, it will let Nagios know about it immediately. Hosts and service configurations are the building blocks of Nagios Core. The -S option is not working with 2.0 plugins. By using this website, you agree with our Cookies Policy. Set enable_notifications=0 in nagios.cfg. This plugin uses systemctl is-active command, please check you have systemd. Add additional tags that should be sent in the HTTP header. In this tutorial, the following three servers are being used. The sections below provide examples of how to perform these checks using different methods. It looks like that with the default install, theres no configuration set up to tell Icinga where to look for the check_http executable. If I used the first method, I have to keep separate site.pp for each environment. The object needs to have the passive_checks_enabled option set to 1 for Nagios to accept passive check results over the command pipe. Nagios server in this example is hosted on 192.168..150 and an example client is hosted on IP 192.168..200 Exit Codes To identify the status of a monitored service, Nagios runs a check plugin on it. Nagioshttpdgccgd. define service{ Rather, Nagios takes the passive check result to be the actual state the host is in and doesn't try to determine the host's actual state using the reachability logic. You need to add the full path to it in the check_command. The Nagios plugin can be remotely executed on other Linux/Unix machines using NRPE. It can test normal (http) and secure (https) servers, follow redirects, search for strings and regular expressions, check connection times, and report on This can be done to gather all critical errors to a single, central place. Edit the /usr/local/nagios/etc/objects/localhost.cfg file and add the following block: Now we are all set, the only thing pending is reloading Nagios to read the configuration files again. This requires trying to read the entire disk directly from the block device (such as /dev/sda1) and checking if the attempt has failed. When it comes to checking MySQL, it should be kept in mind that MySQL, by default, listens on only the loopback interface 127.0.0.1. Check whether Apache HTTP is running on a remote server using check_http. These plugin states directly translate to service states. These checks are scripts and progams which take input (for example, which host to check, tresholds), do a check and then return an exit code and some performance data. Nagios also offers a way of combining the benefits of both active and passive checks. In the first case, Nagios takes care of the scheduling, and the command only needs to perform the actual checks and mark the results as OK/WARNING/CRITICAL based on how a check command is configured. For example, you can use the 'check_http' plugin to verify that a web server is running, is returning the right text, or has an up-to-date SSL certificate. We want Nagios to monitor this database, and as the application is already using it, we can add a module that reports this to Nagios. Monitoring Website URL Status When you restart the Nagios, this host will start getting monitored by Nagios and the specified services will run. These are real-time graphs showing things like CPU usage, memory usage, and bandwidth. To turn on everything you want to set debug_level=4095. Allow Nagios server to run commands on the client by adding it to the allowed_hosts entry in /etc/nagios/nrpe.cfg. This is how your host definitions look currently . # Nagios Exit Codes OK=0 WARNING=1 CRITICAL=2 UNKNOWN=3 # Weather or not we can trust the exit code from the service management tool. If you would like to use the whole or any part of this article, you need to cite this web page at Xmodulo.com as the original source. Agree (1 + 2 + + 2048), Also note that your debug file will grow quickly and then rotate itself. +1 and if that seems like too much trouble you could always look at the Nagios config files to see what command and parameters need to be run. # Defaults to 0, put to 1 for systemd. This command accepts the host name, status code, and the textual output from a check. I've provided some comments here, but things may not be so # clear without further explanation. We make use of First and third party cookies to improve our user experience. Force a check and you will see exactly how the command is being run. By default, Nagios handles results from active and passive checks differently. Up To: Contents When it is an active check result, Nagios takes the fact that switch1 is down into account and maps the child nodes result into an UNREACHABLE state. Stop once the headers are downloaded. 5 check_http Command Examples 1. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Get your subscription here. The files and information on this site are the property of their respective owner(s). this is THE MOST comprehensive and straight forward turorial I've seen. For example: Nagios Enterprises makes no claims or warranties as to the fitness of any file or information on this website, for any purpose whatsoever. On-demand checks are performed as part of the predictive service dependency check logic. The time performed is specified in seconds. If youve installed Nagios from source, check_httpd command will be located in the /usr/local/nagios/libexec directory. It essentially does the same thing as a debug level of 2048, but can be used on a per-plugin basis. Check WMI Plus includes a service module that can check if a service is stopped. A sample definition for a host that runs an active check if there has been no result provided within the last two hours: The following is an illustration showing when Nagios would invoke active checks: Each time there is at least one passive check result that is still valid (i.e., was received within the past two hours), Nagios will not perform any active checks. If you are new to the Nagios network monitoring system, see the resources at the Nagios website. This is where the location of Nagios log file, status.dat file, lock file and host and services state update interval is defined. check_command /usr/share/nagios/plugins/check_http -H MYIP -u http://MYIP/test.php, Hi, Asking for help, clarification, or responding to other answers. Service or Daemon checks are system processes that run in the background, usually configured to start when the system boots. Nagios Plugins Nagios Plugins does not include a service plugin however the linux-nrpe-agent does provide check_init_service. So the Nagios Core version is 3.5.1. Services are checked by the Nagios daemon: At regular intervals, as defined by the check_interval and retry_interval options in your service definitions. External applications can submit passive host check results to Nagios by writing a PROCESS_HOST_CHECK_RESULT external command to the external command file. This task is really easy as Nagios has a built-in command for this. The first thing that needs to be done in order to use passive checks for your Nagios setup is to make sure that you have the following options in your main Nagios configuration file: It would also be good to enable the logging of incoming passive checksthis makes determining the problem of not processing a passive check much easier. Nagios can monitor different mail server components like SMTP, POP, IMAP and mailq. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. However, two hours after the last passive or active check result was received, Nagios would perform an active check to keep the results up-to-date. For example, a plugin which returns a WARNING state will cause a service to have a WARNING state. check_command check_http -H MYIP -u http://MYIP/test.php A good example might be running a check that takes several hours to completein this case, it does not make sense to raise the global service_check_timeout option, but rather to schedule these checks outside of Nagios and only report the results back to it. In such cases, only reports regarding hard state changes are propagated across Nagios servers. This is because, very often, passive checks are used to report host and service statuses from other Nagios instances. Nagios can tell what the status of the service is by reading the exit code of the check. Yup, just like any other linux flag, the "-" with whatever flags you use will load the flag. How to install and configure Nagios Core. In addition, it is run on the Linux operating system, precisely for the purpose of monitoring devices that are executed on Windows, Unix and Linux operating systems.Its main task is to constantly check key server resources, applications, networks and tasks. See Also: Active Checks, Service Checks, Host Checks. You can tell Nagios to translate DOWN/UNREACHABLE passive check result states to their "proper" state by using the translate_passive_host_checks variable. Nagios understands the following exit codes: A program can be written in any language to work as a Nagios check plugin. Examples: CPU load, RAID status An snmp system is generally considered to have 3 components: Agents Agents expose management information on a device. These checks are useful when you cannot monitor hosts/services on a regular basis. The line should look like: Define the standard checks that you will perform on every client with NRPE. To monitor hosts and services running on remote machines, Nagios executes plugins and tells what information to collect. Testing the Commands from Nagios XI Server Now we will test from the Nagios XI server that the command you just added to the NRPE client on the Linux server is working. It will give you all the available options: Nagios' check_ssh (of course) keeps marking the process as critical since it can't connect on that port. 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The basic workings of service checks are described here Services are checked by the Nagios daemon: On-demand checks are performed as part of the predictive service dependency check logic. What you are doing down is sending a Passive check result for the service SNMP Traps - Users for the host CentOS. When services change state too frequently they are considered to be "flapping". Do whatever you want with a Deploying Nagios Monitoring Services on Secured Red Hat Enterprise Linux 3 Environment: fill, sign, print and send online instantly. 2022 Company, Inc. All rights reserved. Check whether Apache HTTPS is running on a remote server using check_http. I test the command from command line successfull, but when I insert in configuration file (cfg) it gives Error: Service check command check_http -H MYIP -u http://MYIP/test.php specified in service HTTP for host Server01 not defined anywhere! On the client host that you want to use to connect to remote Docker daemon, generate SSH keys from your user account; ssh-keygen. You might also want to give the 'capture' plugin a try. Note: A service must be defined in Nagios before you can submit passive check results for it! In case you don't have the plugin in the Nagios server, you can install it with: So, summarizing, the NRPE will run a script in a remote host, and return the exit code to the Nagios server. You can create a host file inside the server directory of Nagios and mention the host and service definitions. Are there tables of wastage rates for different fruit and veg? Submitting Passive Check Results From Remote Hosts. It can also send reports after a database recovery, or periodically, even if connectivity to the database has been consistently available, so that Nagios has an up-to-date status. The figure shown below shows an active check . Note that there are possible security implications of this change, so it's worth mentioning a few words: The following tuning should do the trick. Nagios comes with a wide range of built-in scripts for monitoring services. See the HTML : 45 check_http plugin is used to verify the status of HTTP server (or HTTPS) that is running on a remote host. Often, there are situations where active checks obviously fit better. This example is going to restart the crond service as it is unlikely to cause any issues. They may or may not work on: 44 # your system, as they must be modified for your plugins. In the following example, we are checking whether the website certificate expires in the next 365 days. The host or the services will be tested again and again till the time the status is permanent. Add the file to the standard Nagios Core location, /usr/local/nagios/libexec. More information on the NSCA addon can be found here. We must install this software there to install the "check_nrpe" plugin that we use to perform active checks using the NRPE. Nagios also offers a tool for sending passive check results for hosts and services over a network. By using this website, you agree with our Cookies Policy. As an example of the use of this script, the command that is sent to Nagios for host01, service PING, status code 0 (OK) and output RTT=57 ms is as follows: A very common scenario for using passive checks is a check that takes a very long time to complete. Services are those which are used by Nagios to check something about a host. So I will add at the end of the file the following block:Advertisement.banner-1{text-align:center;padding-top:20px!important;padding-bottom:20px!important;padding-left:0!important;padding-right:0!important;background-color:#eee!important;outline:1px solid #dfdfdf;min-height:335px!important}if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'howtoforge_com-banner-1','ezslot_4',111,'0','0'])};__ez_fad_position('div-gpt-ad-howtoforge_com-banner-1-0');.banner-1{text-align:center;padding-top:20px!important;padding-bottom:20px!important;padding-left:0!important;padding-right:0!important;background-color:#eee!important;outline:1px solid #dfdfdf;min-height:335px!important}if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'howtoforge_com-banner-1','ezslot_5',111,'0','1'])};__ez_fad_position('div-gpt-ad-howtoforge_com-banner-1-0_1');.banner-1-multi-111{border:none!important;display:block!important;float:none!important;line-height:0;margin-bottom:7px!important;margin-left:auto!important;margin-right:auto!important;margin-top:7px!important;max-width:100%!important;min-height:250px;padding:0;text-align:center!important}. Some methods support checking multiple services at once. Nagios can tell what the status of the service is by reading the exit code of the check. 5 check_http examples This file location depends on the configuration you've done, in my case it is in /usr/local/nagios/etc/objects/commands.cfg. It can report each problem when accessing the database. You never know how many (if any) traps or alerts you'll receive in a given time frame, so it's not feasible to just monitor their status every few minutes. Making statements based on opinion; back them up with references or personal experience. Can I tell police to wait and call a lawyer when served with a search warrant? There are many more services in Nagios which can be used to monitor pretty much anything on the running host. Nagios can monitor DNS service by asking the DNS server to either resolve a specific fully qualified domain name (FQDN), or by asking the server to use the dig tool. We can also do it at a contact level, by disabling notifications . In most cases you'll use Nagios to monitor your hosts and services using regularly scheduled active checks. I just used that simple script as an example, any language can be used to write your own custom plugin. An example shell script of how to submit passive service check results to Nagios can be found in the documentation on volatile services. Default is HTTP/1. For HTTPS running on a different port, do the following. Using Python Automation to interact with network devices [Tutorial], OpenCV: Detecting Edges, Lines, and Shapes. The plugins can be in any language, Nagios only cares They can be the following: 0: OK Nagios Plugins does not include a service plugin however the linux-nrpe-agent does provide check_init_service. $ vi /usr/local/nagios/etc/servers/devserver.cfg The following is a sample script that will accept the host name, status code, and output from a check and will submit these to Nagios: As an example of the use of this script, the command that is sent to Nagios for host01, status code 2 (UNREACHABLE) and output router 192.168.1.2 down would be as follows: When submitting results, it is worth noting that Nagios might take some time to process them, depending on the intervals between Nagios checks of the external command pipe. A good example would be a server that is a part of an application, processing job queues using a database. Learn more about Stack Overflow the company, and our products. ##### # # NAGIOS.CFG - Sample Main Config File for Nagios # # Read the documentation for more information on this configuration # file. In cases where the checks require the deployment of long-running processes or monitoring information constantly, this should be done as a passive service. Nagios can monitor DNS service by asking the DNS server to either resolve a specific fully qualified domain name (FQDN), or by asking the server to use the dig tool. This defines that check_nrpe is the command and check_root_home_du is the value of $ARG1$. More information on the flap detection logic can be found here. can nagios adjust its check time based on the status info? Save my name, email, and website in this browser for the next time I comment. An external application checks the status on hosts/services and writes the result to External Command File. It allows the implementation of plugins, developed by the community, or even allows us to configure our own monitoring scripts. Service status codes are the same as those for active checks0 for OK, 1 for WARNING, 2 for CRITICAL, and 3 for an UNKNOWN state. Plugin then gets executed on the remote machine where is collects the required information and sends then back to Nagios daemon. Nonetheless, they can be tuned to match the requirements. When a host or service is down for a very short duration of time and its status is not known or different from previous one, then soft states are used. When Nagios daemon reads external command file, it reads and sends all the passive checks in the queue to process them later. Up To: Contents These are executed on regular intervals, as defined by check_interval and retry_interval. Establish a terminal session to your Nagios XI server and execute the following command: Furthermore , Nagios can also check whether TCP port 80 (web server) is reachable e.g., the server is online but Apache/IIS is not responding. Nagios also supports a way to monitor hosts and services passively instead of actively. A user nagios is created for both localhost and for any host. Base your decision on 2 verified in-depth peer reviews and ratings, pros & cons, pricing, support and more. More information on how this works can be found here. The daemon will listen for connections from remote clients, perform some basic validation on the results being submitted, and then write the check results directly into the external command file (as described above). It is possible to configure Nagios so that it will receive status information sent over a command pipe. Remember that the $USER1$ variable, is a local Nagios variable set in the resource.cfg file, in my case pointing to /usr/local/nagios/libexec. If an application that resides on the same host as Nagios is sending passive host or service check results, it can simply write the results directly to the external command file as outlined above. Pass the specified string as User Agent in HTTP header. When new information regarding a service gets passed to Nagios via the external commands pipe, Nagios treats it the same way as if it had been received by an active check. This yields less output to dig through. service_description check http://MYIP/test.php Submitting Passive Host Check Results External applications can submit passive host check results to Nagios by writing a PROCESS_HOST_CHECK_RESULT external command to the external command file. These checks help ensure that the dependency logic is as accurate as possible. The following diagram shows how both active and passive checks are performed by Nagios. When a host is reported to be DOWN as a passive check result, Nagios does not perform a translation from DOWN to UNREACHABLE. I will leave this script with all the other Nagios plugins inside /usr/local/nagios/libexec/ (This directory may be different depending on your confiugration). Note: Passive host checks are normally treated as HARD states, unless the passive_host_checks_are_soft option is enabled. Passive checks require all the logic related to what should be reported and when it should be checked to be put in an external application. NPCA allows you to check multiple services, here is an example that checks for some services that are running and some that are stopped. Once the host and services are configured on Nagios, checks are used to see if the hosts and services are working as they are supposed to or not. Nagios, the Nagios logo, and Nagios graphics are the servicemarks, trademarks, or registered trademarks owned by Nagios Enterprises. Monitor whether the apache server is available. This usually calls for some effort. The service check runs in a child process that was fork()ed from the main Nagios daemon. It's pretty simple. Scheduled service checks are run in parallel. Note: Certain nodes in the above example have combined check results, such as memory/virtual, memory/swap, and processes. If you preorder a special airline meal (e.g. In such cases, Nagios decides when a check is to be performed, runs the check and stores the result. Unlike with active host checks, Nagios does not (by default) attempt to determine whether or host is DOWN or UNREACHABLE with passive checks. Difficulties with estimation of epsilon-delta limit proof, The difference between the phonemes /p/ and /b/ in Japanese. Far better then Nagios documentation. As this tutorial is based on Debian 9, I will show as an example how to install it, but you can find instructions for any distribution. Find the plugin you want to run (if you're not sure, compare what you see in your plugins directory on your Linux box with the plugins located here: http://exchange.nagios.org/directory/Plugins, or try running "./plugin-name -h" to get the help info about the plugin). In this tutorial, we'll install Nagios on an Ubuntu 19.10 server, but these steps should work on any Debian-based distro. Indicate content type in header for POST request, Regular expression can span to new line (Use this with -r or -R option), Use this regular expression to search for string in the HTTP page, If the site user basic authentication send uid, pwd in the format uid:pwd. Can i specify what a valid response is, i.e. Enable and restart the nrpe service: [user@mon]# systemctl enable nrpe [user@mon]# systemctl restart nrpe. When Nagios plans and receives results from active checks, it takes the actual network topology into consideration and performs a translation of the states based on this. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Monthly digest of what's new and exciting from us. The next parameter specifies the number of seconds after which Nagios should consider the results to be out of date. To allow it to grow bigger before rotating, add more zeroes, for example. just because i had already looked in the commands.cfg file to figure out which commands were running, but i wanted to know what flags were being set. If the situation involves reporting problems from other applications or machines, it is definitely a use case for a passive check. You can create a host file inside the server directory of Nagios and mention the host and service definitions. Copyright (c) 1999-2014 Nagios Plugin Development Team <devel@nagios-plugins.org> This plugin tests the HTTP service on the specified host. I am gettinr this error in nagios3. thanks! if one of my checked systems goes down, and therefore fails a PING check, I do NOT need to be notified that a file system is unavailable, or that SSH is down, too. This way, Nagios can help monitor the accessibility of both MySQL servers and the database stored within the servers. Default is 10 seconds. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? To learn more, see our tips on writing great answers. More information on cached checks can be found here. NSClient++ includes a service module that can check if a service is running. Having managed large Nagios installations for many years, assigning services to hostgroups is an anti pattern and can make things complicated fast if your environment gets big. On any device & OS. Contribute to vishalsingh17/GitiPedia development by creating an account on GitHub. Nagios's primary mode of "service checking" is called an active check. 2. Stats Graphs - Live data graphs of CPU, memory, interface bandwidth, and disk usage. Depending on the status received on hosts and services, appropriate action is taken. All other servicemarks and trademarks are the property of their respective owner. By default Nagios supports URL monitoring and there is an command check_http, however if you want to monitor URL like SSL certification you can also do by extending the command options. So in the server set the files: /usr/local/nagios/etc/objects/commands.cfg: /usr/local/nagios/etc/objects/nrpeclient.cfg: Note that the ! There are also different types of checks including external applications or devices that want to report information directly to Nagios. You do this with nagios -v command as root: Ensure it returns 0 errors and 0 warnings and proceed to reload the service: After reloading the service, you will see the associated check in the localhost. Enjoy unlimited access on 5500+ Hand Picked Quality Video Courses. Nagios Core and Nagios XI has a features to monitoring website URL status. nagiostats provides statistics of which only the part `Services Ok/Warn/Unk/Crit: 8 / 0 / 0 / 0` are interesting to us, so we are using grep to extract this line. To figure this out I set nagios into debug mode with the configuration like this. Consider that you have put your host definitions inside host1.cfg file in /usr/local/nagios/etc/objects directory. Copy the configuration file to the Apache directory: /usr/bin/install -c -m 644 sample-config/httpd.conf /etc/apache2/sites-available/nagios.conf Install the Nagios Plugins to have a set of tools to monitor your different services: apt install build-essential libssl-dev gcc When it comes in as a passive check, no state translation is done and Nagios stores the host and all child nodes being down. The following directive allows it: Setting up hosts or services for passive checking requires an object to be defined and set up so as not to perform active checks. Nagios Core is an Open Source system for monitoring hosts, networks and services. How can I make Status Information for Nagios services easier to read? How can I get it to work with https with Nagios4 and plugins 2.x? This increases the security of the database. Sometimes I find it tricky figuring out exactly what a plugin is doing. The scripts stored in /etc/nagios-plugins/config/ can shed some light on the awesome capabilities of Nagios. When a URL is redirected, use this to either follow the URL, or send ok, warning, or critical notification, Specify the minimum and maximum page size expected in bytes. This feature is only available to subscribers. Nagios will still handle all notifications, event handlers, and dependencies between hosts and services. http://www.waggy.at/nagios/capture_plugin.htm, Go to your plugin directory - in my example it is, Type you plugin name - in my example it is, now run the full command - (plugin name) -H (hostname) -p (port number), However in this example port number is optional, in your config file which is look something like below (myserver.cfg) and you want to run check_cpu from command line, to check instantly (without GUI green or red), Try this - (plugin full path) - H (servername) -c (checkname).

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