This is a text-only version of the following page on https://raymii.org: --- Title : Nagios plugin to check CRL expiry in minutes Author : Remy van Elst Date : 02-05-2013 URL : https://raymii.org/s/software/Nagios_plugin_to_check_CRL_expiry.html Format : Markdown/HTML --- This is a nagios plugin which you can use to check if a CRL (Certificate Revocation List, public list with revoked certificates) is still valid. This is based on the check_crl.py plugin from [Michele Baldessari][1]. It is modified it so that it checks the time in minutes (for more precision) instead of days, it has a GMT time comparison bug fixed and I've added error handling so that if the plugin cannot get a crl file (because the webserver is down) it gives a Critical error in nagios.

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#### Download [Download the plugin from my github][3] [Download the plugin from raymii.org][4] #### Install and Usage This guide covers the steps needed for Ubuntu 10.04/12.04 and Debian 6. It should also work on other distro's, but make sure to modify the commands where needed. Make sure you have openssl, python3 and a module needed by the script installed on the nagios host: apt-get install python3 openssl python-m2crypto Now place the script on the host. I've placed in _/etc/nagios/plugins/check_ crl.py_. wget -O /etc/nagios/plugins/check_crl.py http://raymii.org/s/inc/downloads/check_crl.py Make sure the script is executable: chmod +x /etc/nagios/plugins/check_crl.py Now test the script. I'm using the URL of the Comodo CA CRL file which is the CA that signed my certificate for raymii.org. /etc/nagios/plugins/check_crl.py -u http://crl.comodoca.com/PositiveSSLCA2.crl -w 480 -c 360 OK CRL Expires in 5109 minutes (on Thu May 9 07:30:32 2013 GMT) /etc/nagios/plugins/check_crl.py -u http://crl.comodoca.com/PositiveSSLCA2.crl -w 5200 -c 360 WARNING CRL Expires in 5108 minutes (on Thu May 9 07:30:32 2013 GMT) /etc/nagios/plugins/check_crl.py -u http://crl.comodoca.com/PositiveSSLCA2.crl -w 5000 -c 5300 CRITICAL CRL Expires in 5108 minutes (on Thu May 9 07:30:32 2013 GMT) Lets add the nagios command: define command{ command_name crl_check command_line /etc/nagios-plugins/check_crl.py -u $ARG1$ -w $ARG2$ -c $ARG3$ } And lets add the command to a service check: define service { use generic-service host_name localhost service_description Comodo PositiveSSL CA2 CRL contact nagiosadmin check_command crl_check!http://crl.comodoca.com/PositiveSSLCA2.crl!24!12 } The above service check runs on the nagios defined host "localhost", uses the (default) service template "generic-service" and had the contact "nagiosadmin". As you can see, the URL maps to $ARG1$, the warning hours to $ARG2$ and the critical hours to $ARG3$. This means that if the field _"Next Update:"_ is less then 8 hours in the future you get a warning and if it is less then 6 hours you get a critical. #### Changelog 03-04-2013: - Changed time to minutes for more precision - Fixed timezone bug by comparing GMT with GMT 06-11-2012: - Changed checking interval from dates to hours - Added error catching if a crl file cannot be retrieved. [1]: http://acksyn.org/?p=690 [2]: https://www.digitalocean.com/?refcode=7435ae6b8212 [3]: https://github.com/RaymiiOrg/nagios [4]: https://raymii.org/s/inc/downloads/check_crl.py --- License: All the text on this website is free as in freedom unless stated otherwise. This means you can use it in any way you want, you can copy it, change it the way you like and republish it, as long as you release the (modified) content under the same license to give others the same freedoms you've got and place my name and a link to this site with the article as source. This site uses Google Analytics for statistics and Google Adwords for advertisements. You are tracked and Google knows everything about you. Use an adblocker like ublock-origin if you don't want it. All the code on this website is licensed under the GNU GPL v3 license unless already licensed under a license which does not allows this form of licensing or if another license is stated on that page / in that software: This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . Just to be clear, the information on this website is for meant for educational purposes and you use it at your own risk. I do not take responsibility if you screw something up. Use common sense, do not 'rm -rf /' as root for example. If you have any questions then do not hesitate to contact me. See https://raymii.org/s/static/About.html for details.