Open Source System Management Conference 2012
For anyone interested, I will be speaking at the Open Source System Management Conference 2012 in Bolzano, Italy on May 10th, 2012. If you would like to attend, please check it out below. There is going to be a lot of great speakers and informative lectures going on.
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Save the date! |
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Thursday, May 10th - Bolzano / Italy - 9.00 a.m.
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International keynote speakers Lively discussions Shared experiences |
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The yearly Open Source System Management Conference goes in its 4th edition. The event over the past years has grown to one of the most important meets in Europe for IT managers, system administrators and everyone interested in Open Source monitoring solutions like Nagios, Cacti, Shinken or Icinga. Join this free event and get in touch with international experts presenting relevant trends, new strategies, actual projects Date and Location: Who should attend: IT managers, system administrators Free entry: Overview of this year´s speakers: Jeffrey Hammond, Principal Analyst Forrester Research (US) |
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——————————————————————————————————————————————————- ****** NEWS – Find further Conference news on our Blog or go directly to the Conference´s Webpage – NEWS ******
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April 20, 2012
· 
Jimmy · 
No Comments
Posted in: Cacti
Querying Nagios NRPE Client via PHP
I recently had the idea to write an agent for a few windows servers to execute some custom commands so I could graph the data in Cacti. I have dabbled in making my own Windows SNMP extension agents in the past (and I love SNMP) and while they work well; I really didn’t want anything that complicated.
Now not being someone to re-invent the wheel unless I have to, I started looking around at a few other existing agents. A few of the requirements I had in mind were that I didn’t want the communication in plain text, it needs to be somewhat secure (password or ACL), it needs to be fairly easy to install and configure custom commands, and most importantly I need to be able to easily communicate with the agent over PHP. After finding agent after agent that did 1 or 2 of my requirements, I settled on the Nagios NRPE Agent. While it does have some quirks, it does satisfy the first 3 of my requirements, so all I would have to work out is the 4th. The NRPE Agent can use SSL to communicate between the monitoring server and the agent. While it does not have the ability to require a password, it does allow me to set an ACL on the agent to specify the IP addresses allowed to communicate to it. Configuration is just editing a text config file to add my custom commands, which is really simple. It also makes it pretty easy to push any new updates to my servers.
As for the 4th requirement, communicating with the agent from PHP. I wanted to do this, so I could write some Cacti Script Server scripts, and not have to launch a new process to then query the agent. For NRPE, you normally would have to run the check_nrpe executable with the command line arguments for the command. This was messy and an extra step which would add some latency and slow down my polling. I looked around, and really couldn’t find much info on the protocol NRPE uses between the client and host. I did finally manage to find a perl script that did basically what I wanted, or at least laid out the basics of the required packet for me, so I didn’t have to resort to Wireshark to figure it out. The only thing required was to figure out exactly what it was doing, and then implement the same thing in PHP. The perl script was a few hundred lines of code, and had 4-5 required libraries, which was something I was going to have to do away with.
A few of the tidbits I gleamed. I first made the mistake of attempting to use fsockopen to create the SSL connection, but for SSL to work with NRPE, it seems to require the use of the ADH cipher. Just trying to do a straight up SSL2 or SSL3 connection is going to fail with an error about the cipher (check the agent log). This didn’t pose much of a problem though, since PHP also has lots of nice built-in functions for dealing with SSL streams, and its really easy to change the cipher used with those functions. This also makes it easy, since I really don’t have to deal with certificates or anything else you would normally need to do with SSL. The next thing is that the NRPE agent expects the packet to always be the exact same size no matter the command. We are basically going to have to pad the command with nulls to be 1024 in length, we then add all our CRC checksums and other misc headers to this. Overall the packet itself is very simplistic, and doesn’t include anything really complicated to create.
Anyway, on to some code. This is the simple script I wrote to test querying the agent. Read the rest of this post »
February 18, 2012
· Jimmy · No Comments
Posted in: Cacti
CactiEZ v0.7 – Update
As the completion of the latest version of CactiEZ nears, I figured I would give you all a sneak peak into what is coming.
May 6, 2011
· Jimmy · 5 Comments
Posted in: Cacti, CactiEZ
CactiEZ – Centos 5
This past weekend I was feeling a bit under the weather, so I took some time off and rebuild my CactiEZ CD using CentOS 5. Here a few bullet points
December 7, 2009
· Jimmy · 12 Comments
Posted in: CactiEZ
ESXi 4.0 – Lessons Learned
I’m not sure how many people were paying attention on a Friday night / Saturday morning, but I decided to do the long put off upgrade to ESXi 4.0 (from an old CentOS 4 install running VMWare Server v1.0, yuck). While it wasn’t an extremely painful experience, I can say that I wish a few things were more common knowledge on the internet.
To begin the install was easy, I just had to do a little prep work first. Since my websites were going to be offline (included the others I host for other people) I wanted to do a redirection of all HTTP traffic to another host which would stay up so that I can display a page about the site being under maintenance. Normally you would use a F5 or something to do this for you, but I certainly don’t have anything that fancy laying around so I had to settle for something simpler. I borrowed a small ASUS Eeepc from my good friend Brian Yeager. I did a quick install of windows (could have done linux too, but I had my windows CD handy already) and installed XAMPP on it. I did a quick index.html and added a .htaccess file to do a redirect of any webpage back to that index.html (so if you tried to goto download.php it would redirect, etc…). Now this was easy enough to do. I gave it a spare static IP I had and it was up and running. I had originally planned on doing a Destination NAT on my Mikrotik to redirect all port 80 traffic over to this server, but I ran into a few issues and decided to instead just add the IPs of the VMs to this server as I take them off line. Simple enough.
October 10, 2009
· Jimmy · 9 Comments
Posted in: Cacti