I am not sure if this is related with PHP code/Joomla plugin/component or server issue so to go and post my question at serverfault.
I have a dedicated server running CentOS release 6.4 (Final) and CPanel 11.38.1 (build 15) with [Apache/2.2.24 (Unix) PHP/5.2.17] and recently we had brute force attacks which were causing system hangs with messages like "HANG: chkservd on server". After setting up a DenyHosts and changing ssh default port the server stabilized for some days until it started to suddenly hang with no specific errors in logs nor any email notifications.
The server runs just one website but with some traffic (about 2000 visitor per day) and a large Joomla database. The site was up and running flawless since March 2013, until two weeks ago.
After investigating, I have noticed that the error_log under the public_html (default joomla site directory) size was over 200MB but with no specific error messages but just lines with date/time and zeros "0"!
[24-Jul-2013 12:09:18] 0
[24-Jul-2013 12:09:18] 0
[24-Jul-2013 12:09:18] 0
[24-Jul-2013 12:09:19] 0
[24-Jul-2013 12:09:19] 0
[24-Jul-2013 12:09:19] 0
[24-Jul-2013 12:09:19] 0
[24-Jul-2013 12:09:20] 0
[24-Jul-2013 12:09:26] 0
[24-Jul-2013 12:09:26] 0
[24-Jul-2013 12:09:30] 0
Almost every second, thousand lines like those above! Sometimes the site crashes with "jos-Error: Application Instantiation Error" and some other times with an error:
PHP Fatal error: Call to a member function get() on a non-object in ...
which is due to database issue when joomla tries to load params from the database and it fails.
I have setup a backup of the site on a local windows server machine with apache and php installed [Apache/2.2.19 (Win32) PHP/5.3.6] and these zero "0" errors also spawn on every site call with some more details in \Apache2\logs\error.log like:
[Wed Jul 24 14:42:32 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/
[Wed Jul 24 14:42:32 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/
[Wed Jul 24 14:42:32 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/
[Wed Jul 24 14:42:33 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/
[Wed Jul 24 14:42:33 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/
[Wed Jul 24 14:42:33 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/
[Wed Jul 24 14:42:56 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/mousiki
[Wed Jul 24 14:42:56 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/mousiki
[Wed Jul 24 14:42:56 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/mousiki
[Wed Jul 24 14:42:57 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/mousiki
[Wed Jul 24 14:42:57 2013] [error] [client 192.168.1.66] 0, referer: http://virtdev.ose.domain.com/mousiki
thus I assume it is not server related, but Joomla site related from a plugin/component.
Also we have scanned the site with online site scanners and plain file search with antivirus tools for bot injections with no possitive results.
How we can locate what is causing these zeros as errors?