Force a check and you will see exactly how the command is being run. check_http: command not found. Note: A host must be defined in Nagios before you can submit passive check results for it! The Nagios server is running on Ubuntu. The best answers are voted up and rise to the top, Not the answer you're looking for? To check whether a specific webpage is available, use the -u option as shown below. The __HOST__ is a special service name, which represents the host check in Nagios. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? This is how your host definitions look currently . One of the problems is that such checks can take only a couple of seconds to completea typical timeout for an active check to complete is 10 or 30 seconds. If youve installed Nagios from source, check_httpd command will be located in the /usr/local/nagios/libexec directory. Simple invoke the command with -s parameter and the name of the service Example of use ./check_service -s ntpd Thank you! 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. Start Nagios Daemon Using nagios -d Typically you would execute "service nagios start" to start the Nagios daemon, which really calls the /etc/rc.d/init.d/nagios script. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. This requires trying to read the entire disk directly from the block device (such as /dev/sda1) and checking if the attempt has failed. Learn more about Stack Overflow the company, and our products. . Asking for help, clarification, or responding to other answers. 28. 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. Sometimes I find it tricky figuring out exactly what a plugin is doing. The processing of active and passive check results is essentially identical. 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. Also, depending on your configuration you should add this last file to the main file (/usr/local/nagios/etc/nagios.cfg): Check the configuration and, if no errors or warnings, reload the service: And now you have a new custom check on a host: Nagios has a huge library of plugins available at Nagios Exchange. Consider the following script (check_warnings.sh): Based on the information provided by the nagiostats tool, I assume everything is ok if there are five or less services in Warning state.if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'howtoforge_com-medrectangle-4','ezslot_1',108,'0','0'])};__ez_fad_position('div-gpt-ad-howtoforge_com-medrectangle-4-0');if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'howtoforge_com-medrectangle-4','ezslot_2',108,'0','1'])};__ez_fad_position('div-gpt-ad-howtoforge_com-medrectangle-4-0_1');.medrectangle-4-multi-108{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}. For example: nagios@nagiosserver:~/ > $ ssh-keygen -t dsa Generating public/private dsa key pair. . This plugin uses systemctl is-active command, please check you have systemd. It shows what is performed by Nagios in both cases and what needs to be done by the check command or an external application for passive checks. Unlike with active host checks, Nagios does not (by default) attempt to determine whether or host is DOWN or UNREACHABLE with passive checks. 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. See Also: Active Checks, Host Checks, Check Scheduling, Predictive Dependency Checks. More information on the flap detection logic can be found here. By default you do not need to change any of the lines in this file and . Nagios is the most popular tool which is used to monitor hosts and services running in your IT infrastructure. There are many more services in Nagios which can be used to monitor pretty much anything on the running host. Nagios will ignore all check results for hosts that had not been configured before it was last (re)started. Nagios check_by_ssh returns status 3 even though running the command manually works? How can we prove that the supernatural or paranormal doesn't exist? These types of checks are called Passive Checks. All other servicemarks and trademarks are the property of their respective owner. For example, to set up a very similar service, all we need to do is to use the same parameters as those for the hosts: In this case, Nagios will never perform any active checks on its own and will only rely on the results that are passed to it. thanks! The plugins can be in any language, Nagios only cares They can be the following: 0: OK NSClient++ includes a service module that can check if a service is stopped. Active checks can be used to "poll" a device or service for status information every so often. :), I will also menton for new users that using, The debug_levels are binary - 2048 only turns on messages from macros. The module defines a "good" service as one that is running and a "bad" service is one that is not running, so you can define critical is when more than 0 "good" services exist. Note: Certain nodes in the above example have combined check results, such as memory/virtual, memory/swap, and processes. Learn more. This increases the security of the database. The Nagios Service Check Acceptor (NSCA ) addon has historically been the addon of choice for Nagios administrators that need to establish data feeds or passive check transmission between Nagios installations. In order to use them, the host needs to be configured to accept passive checks results. You can create a host file inside the server directory of Nagios and mention the host and service definitions. check_http plugin is used to verify the status of HTTP server (or HTTPS) that is running on a remote host. But if the monitoring application is not running or some other issue prevents it from reporting, Nagios can use active checks to keep the service status upto-date. The script should then post results to the Nagios daemon. Up To: Contents Often, there are situations where active checks obviously fit better. Another difference is that active checks require much less effort to be set up when compared to passive checks. Treat NRPE connection failures as 'UNKNOWN' service state, and don't notify on UNKNOWN services . I am gettinr this error in nagios3. You'll see the following line inside the /etc/rc.d/init.d/nagios script for the Nagios startup: $NagiosBin -d $NagiosCfgFile 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. For Nagios, many, many Oracle plugins are available for checking database availability and performance. Test Server 1: custom application (TCP Port. I've provided some comments here, but things may not be so # clear without further explanation. Go to the /usr/local/nagios/libexec dir (assuming you have installed nagios from source, if you have used a package from your distribution, check the docs of your package): $ cd /usr/local/nagios/libexec execute the check_dns plugin with the --help switch. Force a check and you will see exactly how the command is being run. Remember to allow the execution of the script: if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'howtoforge_com-box-4','ezslot_6',110,'0','0'])};__ez_fad_position('div-gpt-ad-howtoforge_com-box-4-0'); The result is a text message and an exit code: This step will be the same with your own plugins, and if you download a third-party plugin from the internet as well. Enter file in which to save the key (/home/nagios/.ssh/id_dsa): Enter passphrase (empty for. 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. NSCA stands for Nagios Service Check Acceptor. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Periodically when these checks are processed, notifications or alerts are sent depending on the information in check result. In this tutorial, we'll install Nagios on an Ubuntu 19.10 server, but these steps should work on any Debian-based distro. External applications can submit passive service check results to Nagios by writing a PROCESS_SERVICE_CHECK_RESULT external command to the external command file. @sunardo I just ran into this exact same thing. To figure this out I set nagios into debug mode with the configuration like this. Nagios also offers a tool for sending passive check results for hosts and services over a network. In many cases, the time taken is not enough, as some checks need to be performed over a longer period of time to have satisfactory results. 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. Next, update the remote Docker daemon DNS details on your hosts file if there is no local DNS; sudo tee -a "192.168.59.48 docker01.kifarunix.com docker01" >> /etc/hosts. The NSCA addon consists of a daemon that runs on the Nagios hosts and a client that is executed from remote hosts. Enable and restart the nrpe service: [user@mon]# systemctl enable nrpe [user@mon]# systemctl restart nrpe. 1. Nagios understands the following exit codes: A program can be written in any language to work as a Nagios check plugin. The following illustration shows how results from active and passive checks are treated differently by Nagios: In both the cases, a check result stating that the host is down is received by Nagios. Nagios: Simple Oracle Check. Does anyone have a working example of a dependencies.cfg file for nagios? 2022 Company, Inc. All rights reserved. This way, Nagios can help monitor the accessibility of both MySQL servers and the database stored within the servers. . There are no attachments for this article. This file location depends on the configuration you've done, in my case it is in /usr/local/nagios/etc/objects/commands.cfg. An example shell script of how to submit passive service check results to Nagios can be found in the documentation on volatile services. How can I manually run a nagios check from the command line? UNKNOWN 2013-04-25 18:11:24 0d 0h 55m 37s 4/4 RESPONSE: UNKNOWN ERROR: /usr/bin/nc does does not exist, i am really getting frustrate from this nagios error, nitin: you need to install the netcat package for your distribution which will provide /usr/bin/nc, I had been using this plugin for a while. Service - Started Check to see if a service is started. However, if there are no jobs to process and the application is not using it, Nagios will not have up-to-date information about the database. This setting is done on all MySQL servers. Using Python Automation to interact with network devices [Tutorial], OpenCV: Detecting Edges, Lines, and Shapes. Check whether a document is older than x seconds. Check HTTPS Check whether Apache HTTPS is running on a remote server using check_http. If a service is set up with a max_check_attempts directive of 5, then the same number of passive check results would need to be passed in order for Nagios to treat the new status as a hard state change. On-demand checks are performed as part of the predictive service dependency check logic. You need to add the full path to it in the check_command. All other servicemarks and trademarks are the property of their respective owner. Is there a proper earth ground point in this switch box? this is THE MOST comprehensive and straight forward turorial I've seen. # These are some example service check commands. As with submitting host check results, it is worth mentioning that Nagios will take some time to process passive check results as they are polled periodically from the external commands pipe. debug_level=2048 With nagios in debug mode I simply tail the debug_log file debug_file=/var/log/nagios3/nagios.debug. If you preorder a special airline meal (e.g. There are also different types of checks including external applications or devices that want to report information directly to Nagios. This directive is used to perform scheduled checks of the hosts for the number you set; by default it is in minutes. Code-GPT is an extension for VS Code that provides you instant explanations for your code within the code editor using AI. VS Code extension | 35 comentarios en LinkedIn Xmodulo 2021 About Write for Us Feed Powered by DigitalOcean, Creative Commons Attribution-ShareAlike 3.0 Unported License, Monitor whether MySQL is running by checking port, Monitor the availability of certain database. 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. As mentioned earlier, Nagios can forgo the actual execution of an on-demand service check if it can use the cached results from a relatively recent service check. Why is there a voltage on my HDMI and coaxial cables? Nagios dependencies.cfg example file. It also defines Nagios user and group under which Nagios instance is running. Define the checks on /etc/nagios/nrpe_local.cfg. In Nagios, 2 types of checks are performed on hosts and services . Allow Nagios server to run commands on the client by adding it to the allowed_hosts entry in /etc/nagios/nrpe.cfg. I will use a simple example. This feature is only available to subscribers. Monitor whether the apache server is available. How Nagios process handles passive check results can be defined in the main Nagios configuration file. }. To use a custom script as a plugin to run remotely through NRPE, you should first write the script on the server, for instance in /usr/local/scripts/check_root_home_du.sh: The previous script is a very simple example, checking the disk usage of the directory /root and setting a threshold for considering it OK, Warning or Critical. 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. How to Write a Custom Nagios Check Plugin, /usr/local/nagios/etc/objects/commands.cfg, /usr/local/nagios/etc/objects/localhost.cfg, /usr/lib/nagios/plugins/check_users -w 5 -c 10, /usr/local/nagios/etc/objects/nrpeclient.cfg, Generic installation on Debian-based Client, Set the NRPE Check on the Server Configuration Files, Develop Network Applications for ESP8266 using Mongoose in Linux, How to Setup IKEv2 IPSec VPN Using strongSwan and Let's Encrypt on Rocky Linux 9, ISPConfig Perfect Multiserver setup on Ubuntu 20.04 and Debian 10, Generating Web Site Statistics With AWStats & JAWStats On Debian Lenny, How to Install Jitsi Video Conference Platform on Debian 11, How to Install LAMP Server Stack on Ubuntu 22.04, How to use grep to search for strings in files on the Linux shell, You have Nagios installed and running (You can follow this. After installing nagios and nagios-plugins-all (via yum), I've c. These are executed on regular intervals, as defined by check_interval and retry_interval. The default FQDN used for testing is www.google.com, but it can be changed as needed. Nagios executes event handlers to handle hard states. The host status code should be 0 for an UP state, 1 for DOWN and 2 for an UNREACHABLE state. For example, when a web application cannot connect to the database, it will let Nagios know about it immediately. 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. The following is a script that runs the dd system command (visit http://man.linuxquestions.org/index.php?query=dd) to read an entire block device. This is a plugin for Nagios wich you can use to check if a linux service is running. TRUST_EXIT_CODE=0 usage () { cat <<EOF 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. This will give an idea on whether the execution will be successful and what the output of the script will look like. In order to allow remote hosts to send passive check results to the monitoring host, I've developed the NSCA addon. But today when I am trying to post an XML message to the server, from console it works well but does not work with nrpe. 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. Nagios Core is an Open Source system for monitoring hosts, networks and services. NPCA includes a service module that can check if a service is stopped. From the GroundWork Monitor menu, selecting Configuration > Nagios Monitoring > Services > Service Templates presents the options New, Copy, and Modify. This command accepts the host name, service description, status code, and the textual output from a check. rev2023.3.3.43278. 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. NSClient++ allows you to check multiple services, here is an example that checks for two services that are running. In such cases, Nagios decides when a check is to be performed, runs the check and stores the result. If you don't make use of service dependencies, Nagios won't perform any on-demand service checks. In this example we are going to define a service and assign it to localhost, because this check is on Nagios itself. All of the scripts are located at /etc/nagios-plugins/config/ with the executable files stored at /usr/lib/nagios/plugins/. The host or the services will be tested again and again till the time the status is permanent. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If the remote server runs only HTTP and not HTTPS, youll get HTTP CRITICAL Unable to open TCP socket message as shown below. This command accepts the host name, status code, and the textual output from a check. Format is minimum:maximum, Response time in seconds for warning state, Response time in seconds for critical state, Number of seconds to wait before connection times out. Active checks are most common in the Nagios world. The command to submit passive checks is PROCESS_HOST_CHECK_RESULT (visit http://www.nagios.org/developerinfo/externalcommands/commandinfo.php?command_id=115). As mentioned earlier, server-2 has postfix mail server set up on it. So I decided to use the second method. This should enable MySQL to listen on all interfaces, as well as accept incoming connections from user nagios at any host. The NRDP addon allows administrators to migrate from using NSCA to NRDP fairly easily. Nagios Enterprises makes no claims or warranties as to the fitness of any file or information on this website, for any purpose whatsoever. 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. awesome. How to tell which packages are held back due to phased updates. When Nagios checks the status of services, it will be able to detect when a service changes between OK, WARNING, UNKNOWN, and CRITICAL states and take appropriate action. I've # provided some comments here, but things may not be so clear without further # explanation, so make sure to read the HTML documentation! Services that are checked can be in one of four different states: Service checks are performed by plugins, which can return a state of OK, WARNING, UNKNOWN, or CRITICAL. +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. Add additional tags that should be sent in the HTTP header. host_name Server01 They are a web interface and command line tool set to work with Nagios config that have decent default templates and "example" files that you can leverage for common checks. Active checks reach out from the Nagios host and test if a service is doing what it's expected to do. More information on cached checks can be found here. Each of these options opens the Manage Service Template screen.The New option will have no pre-selected directive values, Copy lets you create a new template based on an existing templates properties, and Modify enables the editing of an . Even if its parent host is currently DOWN, the child host state is also stored as DOWN. Add the file to the standard Nagios Core location, /usr/local/nagios/libexec. If you want know more, just read and play with: I'm new to shell and would like to understand and adapt your script would you comment on why this particular adaptation wont work (results unknown - 0 regardless of input parameter sent by the user), countWarnings=$(/usr/local/nagios/bin/nagiostats | grep "Ok/Warn/Unk/Crit:" | sed 's/[[:space:]]//g' | cut -d"/" -f5), echo "example: plugin.sh minimal_counter_for_warning_alert counter_for_critical_alert", if (($warn<=$countWarnings ||$countWarnings==0)); then, echo "OK - $countWarnings services in Warning state", elif (($warn<$countWarnings && $countWarnings<=$crit)); then, echo "WARNING - $countWarnings services in Warning state", echo "CRITICAL - $countWarnings services in Warning state", [emailprotected]:/usr/local/nagios/libexec$ echo $(/usr/local/nagios/bin/nagiostats | grep "Ok/Warn/Unk/Crit:" | sed 's/[[:space:]]//g' | cut -d"/" -f5). So in this blog post is all about how I used Hiera to manage the Dev,Test, Prod Stratos environments. No software installation. Go to the Nagios interface via a web browser and log in as the nagiosadmin user. 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. When the service check has completed, the child process will inform the main Nagios process (its parent) of the check results. The key features of passive checks are as follows: The major difference between active and passive checks is that active checks are initiated and performed by Nagios, while passive checks are performed by external applications. Stop once the headers are downloaded. The flexibility provided by Nagios is perfect for these case scenarios. Some of the scripts provided with Nagios are restricted to the local server only. If you are new to the Nagios network monitoring system, see the resources at the Nagios website. What you are doing down is sending a Passive check result for the service SNMP Traps - Users for the host CentOS. 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. The following file can be modified to do the job. Using the definition below, checks on the host will be performed after every 3 minutes. 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. Note that all the configuration in this section is done on the client to be checked, not in the nagios server. See the HTML : 45 Passive checks are also used when configuring distributed or redundant monitoring installations. 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). The service check runs in a child process that was fork()ed from the main Nagios daemon. Nagios Core and Nagios XI has a features to monitoring website URL status. A good example would be a server that is a part of an application, processing job queues using a database. This tutorial was tested using Nagios Core 4.3.4 on Debian 9.2if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'howtoforge_com-box-3','ezslot_3',106,'0','0'])};__ez_fad_position('div-gpt-ad-howtoforge_com-box-3-0'); Even though Nagios Exchange has thousands of available plugins to freely download, sometimes the status needed to be checked is very specific for your scenario. Note: A service must be defined in Nagios before you can submit passive check results for it! Also, MySQL would not let just any host to connect to it. NRDP has several benefits over NSCA, including: 03-16-2010, 10:31 AM . Based on the condition checked, the plugin can make Nagios aware of a malfunctioning service.
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