CentOS

Inspect dnf configuration.

Instruct dnf to skip confirmation dialog and assume yes for every question.

Parse the fastest available dnf mirror data.

Improve dnf download times.

Simply update Grub on CentOS server.

Sometimes I need to get the package URL on CentOS to store it using Nexus Repository Manager. At first glance, it is not very obvious how to display package URLs, but the actual process is very simple.

Use tsflags plugin to test upgrade process before executing it.

Use versionlock plugin to protect packages from being updated on the CentOS operating system.

Determine whether a full CentOS 7 reboot is required and which services need to be restarted.

Check available security updates for CentOS 7.

Today, I will show you how to manage RPM keyring on the CentOS operating system using a real life example.

Disable auditd daemon during operating system image build process to prevent unnecessary log spikes.

Alter configuration for specific yum repository.

List packages in specific yum repository.

Disable specific yum repository to prevent particular packages from installation or update.

Use yum without downloading or updating its metadata.

Downgrade package using yum.

Download RPM packages from YUM repository using additional yum utilities.

Increase Google Cloud virtual machine instance disk size without service interruption.

Enforcing your own security policy that defines users, SSH keys, and sudo configuration inside custom templates based on official images in Google Cloud requires that you disable Google Accounts service, so it won’t get in the way.

Yesterday I had a small problem. I have added GlusterFS mount point to the fstab but filesystem wasn’t mounted automatically after I rebooted the operating system (CentOS).

I hit an intriguing problem as I needed to relay selected mailboxes rather than the whole domain. I assume that you have already noticed that everything needs to happen on the same domain. It is a rare and quite interesting task so I will quickly describe it here using ISPConfig 3 but beware as this is a very specific topic so I strongly suggest investigating it further before applying any changes.

Hmm… Today I hit a funny problem as I couldn’t install Advanced Policy Firewall from RepoForge (RPMforge) repository on CentOS 6. Fortunately the solution is trivial and doesn’t require any magic…

What to do when you want to analyze data contained in database without overloading the server? The answer is simple as you can use MySQL Master-Slave replication to offload this task. I will describe it briefly here.

A couple of days ago I decided to use the netinstall CD to install CentOS but got somewhat surprised by the “URL Setup” step as I didn’t expect to enter full URL containing installation image.

fping was updated last month (2012-08-19) to version 3.3. Output statistics were directed to stdout instead of stderr so Smokeping (2.6.8) was not updating RRD files as a result.

Short note on how to manage system services using CentOS.

Read requirements and follow installation instructions to integrate Roundcube with ISPConfig 3. Source code is available at GitHub

Today I installed phpMyAdmin on fresh CentOS 6.2 (with EPEL repository) and it was not working. Looking at the Apache logs revealed only a notice: [notice] child pid 41292 exit signal Segmentation fault (11) My Apache and PHP versions: $ httpd -v Server version: Apache/2.2.15 (Unix) Server built: Dec 8 2011 18:07:26 $ php -v PHP 5.3.3 (cli) (built: Jan 11 2012 19:30:40) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies The problem was with eAccelerator PHP module.

If you are using ISPConfig on CentOS and don’t want to bother with self compiled postfix (because of MySQL support) then use CentOS Plus Repository.

Exclude package from an update on CentOS operating system.

Get rid of slow CentOS mirrors on update.