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Welcome to My Blog

This is to share my IT experience with friends all around the world.
I have been working in Linux Fedora Systems for more than 8 years. Its fun to share knowledge and learn..
As everyone knows when a problem arises in your systems "googling" is the way that many depend on..

All the posts here are my working experiences during my working life.. So you can count on it..

I have added the references where I got help in solving IT issues


Tuesday, September 23, 2014

How to monitor user login history on CentOS with utmpdump

A very useful reading for CentOS admins http://xmodulo.com/2014/09/monitor-user-login-history-centos-utmpdump.html.

I was using `last` and `lastb` earlier but feels we can get more information with `utmpdump`. Thanks for Gabriel Cánepa for his article.

Some short notes from his article

utmpdump /var/run/utmp  - show who is currently logged on and what they are doing, and also by uptime to display system up time

utmpdump /var/log/wtmpshow the listing of last logged-in users

utmpdump /var/log/btmp  - show the listing of last failed login attempts

These files are used in last and `lastb` commands to show details of login but by using utmpdump we get more flexibility for filtering

Upgrade PHP 5.3.3 to 5.4 in CentOS

Sometimes we need to upgrade PHP version inbuilt with the OS to newer version. We have been using CentOS for sometimes. It was requested to upgrade PHP to php5.4 in CentOS 6.5 and I have followed the below given link. We were able to upgrade PHP 5.3.3 to  PHP 5.4.32 (cli) (built: Aug 22 2014 07:07:38) smoothly.

If you have such requirement it is safe to follow the link http://www.shayanderson.com/linux/centos-5-or-centos-6-upgrade-php-to-php-54-or-php-55.htm

Even though it is bit old still works fine :-)

Friday, August 8, 2014

Issue with Roundcube when sending Mails

Today we encountered a strange issue after reboot the server running roundcube webmail application. I was able to login to the webmail application over the network, read mails (I received mails) BUT was not able to send mails. The message says nothing but

'could not send mail. Please wait 76531921 seconds'.

I was clueless as the server had no issue with connecting to sendmail server, web server. No issues were detected in SELinux/iptables/network etc.All the services were OK.

Finally we checked the date and time of the server and found the date had reset to past data in 2012... This had confused the webmail service when the users try to send mails.

After reset the data to current settings, all went OK.

ntpdate -u <ntpserverip>

Moral:
There could be a totally strange reason for an issue. You need to check all possibilities without get panic.