Platonic

You had read about nagios plugin which I use in my firefox browser in my previous articles. Let me give you an insight about nagios remote server monitoring. Nagios has been a reliable monitoring tool for many clients for years now.

Nagios comes with lots of plugins which can be used to fine tune the results. While monitoring the remote servers we need to check the service status locally on those servers to understand the condition of service status. check_nrpe is one of those tools which facilitates this feature on Nagios.

The NRPE addon is designed to allow you to execute Nagios plugins on remote Linux/Unix machines. The main reason for doing this is to allow Nagios to monitor “local” resources (like CPU load, memory usage, etc.) on remote machines. Since these public resources are not usually exposed to external machines, an agent like NRPE must be installed on the remote Linux/Unix machines.

The NRPE addon consists of two pieces:

• The check_nrpe plugin, which resides on the local monitoring machine
• The NRPE daemon, which runs on the remote Linux/Unix machine

When Nagios needs to monitor a resource of service from a remote Linux/Unix machine:

• Nagios will execute the check_nrpe plugin and tell it what service needs to be checked
• The check_nrpe plugin contacts the NRPE daemon on the remote host over an (optionally) SSL-protected connection
• The NRPE daemon runs the appropriate Nagios plugin to check the service or resource
• The results from the service check are passed from the NRPE daemon back to the check_nrpe plugin, which then returns the check results to the Nagios process.

Note: The NRPE daemon requires that Nagios plugins be installed on the remote Linux/Unix host. Without these, the daemon wouldn’t be able to monitor anything.

Today I found the answer for one of my questions. I wanted to monitor a server which is not directly connected to internet. I used the above mentioned NRPE plugin to check the status of MySQL service via an another server which had privilege to interact with the db server. It has been made possible via Nagios Indirect checks via check_nrpe. You can find the block diagram explaining the same below.

Its quite easy to configure this just like any other remote service checks done via nrpe daemon. Now I can monitor anything on servers which are locked in a DMZ. Nagios and NRPE made for each other.

Read more : Nagios

Dealing with large files on servers in which you have upload limits etc is always painful. Linux lets us split the files quickly with its split command as follows :

split --bytes=512m original_file.zip file_chunk_

That command will split original_file.zip into files that are 512 MB in size and name the various parts file_chunk_aa, file_chunk_ab, etc. If you want to the file to be split in bytes you can specify b, k can be used for Kilobytes and m for Megabytes.

Its also easy to join these files back in one piece

To join the files back together on Linux issue the following command:

cat file_chunk_* > complete_file.zip

You can even join these files on windows by using the copy command as follows :

copy /b small_file_* joined_file.tar

I have been quite busy this month with both work and studies. Mean while have been making short trips to home and office almost every day. Till yesterday it was quite hard to think about driving as there is no one yet to fill in the next seat. So, I had to go ahead tag along a Pioneer Music system with JBL GTS Series Speakers with Components  and now my car rocks. Hop in when you get time

Pioneer DEH-P5090UB

Features

o Segmented OEL (Organic EL) display
o MP3/WMA/AAC playback
o Direct AUX-in by mini jack (rear)
o USB direct connection: USB 2.0 (full speed)
o iPod direct connection (Optional: use with CD-IU50)
o Bluetooth adapter ready
o IP-Bus
o Advanced Sound Retriever
o EEQ
+ 3-band parametric equalizer
+ HPF/LPF
+ Bass Boost
o Rotary Commander
o Direct Sub Drive
o 3 RCA pre-outs (front + rear + subwoofer)

JBL GTS 650C for Front with Components  and Rear Oval’s

Next I got to put an Amplifier and a sub woofer finish with my audio system shopping.

Its time to Rock…

Today I faced an interesting issue on a HSPComplete box. One of the customer was unable to pop emails from an account. There was no issue with the pop service but I used to get a ERR message after the authentication.

Following is the pop test via TELNET

$ telnet localhost 110
Trying 127.0.0.1…
Connected to testserver (127.0.0.1).
Escape character is ‘^]’.
+OK
user testuser
+OK
pass 123456
-ERR
Connection closed by foreign host.

Log was showing the following message :

Jul 22 22:48:29 testuser popa3d[10007]: Failed or refused to load /var/spool/vmail/testdomain.com/mail/testuser

Here is the pop3d rpm which was found on the server :

popa3d-0.6.4-4.as3.swsoft

Trouble shooting :

Checked inbox for multiple email accounts The mbox file size didn’t affect other email accounts found to be having more emails than this account.

There were no complaints from other customers.

File permissions for the inbox found to be fine along with the ownership etc.

Took a backup of the inbox and emptied it to check if I can successfully login to pop account. That did a trick. But that was not the complete solution.  Customer wanted to pop all his 40k+ emails. I tried to split the mbox file into 50MB chunks, copied the content of the first part to inbox and tried popping the emails. Still there was no luck.

Work around :

While working with the inbox file I found that something is wrong in the first line. I found some content which might have been the subject line of the first message. It means the mbox file is corrupted. When we use mbox format to store emails on the server all the emails coming to an email account will be stored in a single file and the file might get corrupted while popping the emails etc…

I just removed the first email from the mbox file (You can identify the different emails as the email content is stored in plain text and also there will be a line which indicates the beginning of a new message. Its quite easy to understand how emails are stored in mbox file once you look into it) and customer was able to start popping emails without any issues.

You might face this issue on servers using mbox format for inbox. Many plesk, cpanel as well as HSPComplete boxes are still using mbox. Hope this post will help you resolve such issues.

PS: Ensure that you’re using mbox file format. In maildir format you will have cur, new and tmp folders for each account.

Following links will help you understand the MailBox formats better

http://en.wikipedia.org/wiki/Maildir

http://en.wikipedia.org/wiki/Mbox

Me and my recruitment crew @ HKBK Engineering college, Nagawara. Bangalore.

We gave an intro about the career opportunities available in Free and OpenSource World to students who are in search of jobs.

From : cPanel Blog : Posted: 11 Jul 2008 10:35 AM CDT

One Time License Update

As of today, July 11, 2008, cPanel will no longer be offering One Time Licenses. These licenses are not currently inline with the way we deliver our products and do not allow us to provide the same high level of service to our customers that our other license models do. We apologize for the lack of notice however, providing notice would simply allow for more One Time Licenses to be sold which is the opposite intention of this action. Sorry for any inconvenience this may cause

————————————————————————
Off the cPanel Blog

Final bit:

Looks like all proprietary Control Panels are hiking up the prices big time. Recently “Parallels” (Earlier known as SwSoft) increased the prices for their Virtuzzo licenses. Looks like an effect of “Global
economic condition”.

Image source: Sampada.net

Well known Kannada science and technology writer and music critic Prof. G.T Narayana Rao passed away this morning. He used to write science for the masses. His writings were appreciated for its style and simplicity used in language. Its a great loss for Kannada science literature world.

I got to know more about G.T.N after viewing podcast posted at Sampada and his views on technical writing had really moved me. I would like to follow his path and try my best to make technology reachable to all. That will be a small tribute to Prof. G.T.N from my end.

Read more :

• Ismail’s write up: My Father, Stars and G.T.N
  
• Sampada Podcasts (Audio and Video)
• G.T.N Profile and News updates @ Star of mysore
• Teacher’s Day: Yet another Routine Ritual - By G.T.N

The most awaited web browser for internet freaks “Firefox 3″ is now ready. Its about to set the Guinness world record for Most Software Downloaded in 24 Hours. One of the lightest browser available on the earth. If you have never tried Firefox before, today is the best day.

Join your hands with firefox community to set this record.