Tag Archives: CentOS

Migrating a virtual machine from KVM to ESXi

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Migrating a virtual machine from one host to another is usually no big deal if both hosts run the same VMM. But what if one wants to move a VM from a host running a different hypervisor than the target host? In the case of moving a VM from KVM to ESXi that’s just not (easily) possible. However, one can… Read more »

Adding a new disk to a Xen VM

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Create a new image file (10GiB): (Note: You can also create a sparse file with dd’s seek option. Have a look at the dd manpage or the examples on http://en.wikipedia.org/wiki/Dd_(Unix)) Create the new filesystem: Label the filesystem: Edit the DomU’s config file, /etc/xen/<hostname>.cfg and add the new disk: Start the VM: Edit DomU’s /etc/fstab & mount the disk:

Granting access to X server with xhost

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Every X server internally manages an ACL (Access Control List) of those hosts, that are allowed to connect. The server only authorizes connections from X clients, whose host is on that list and rejects access to all others. The xhost program is used to add or revert access to the X server for specified hosts. It’s also possible to specify… Read more »

Dealing with .rpmnew and .rpmsave files

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When an upgrade includes changes to a default configuration file, the package will write either a .rpmnew or a .rpmsave file instead of overwriting the configuration file on your system. Which file a package creates is up to the discretion of the package maintainer. From “Dealing with .rpmnew and .rpmsave files” By Bruce Byfield: An .rpmnew file contains the new… Read more »

Cleaning up locally-installed RPMs with package-cleanup

Sometimes, packages you never actually use get installed as dependency by yum (or even during initial installation by anaconda). package-cleanup is a great tool that helps you find packages not required by other packages. It it part of the yum-utils package which can easily be pulled with yum: 1. Find and review “unused” packages You can find packages not required… Read more »

Netboot CentOS using Attansic L1 Gigabit Ethernet

To update the initrd.img to load additional drivers early in the boot process, normally you would simply run /sbin/mkinitrd and let the script do the work. But what if the initrd.img used during the installation of CentOS lacks an important driver? Maybe you want to netboot CentOS, but the initial ramdisk CentOS provides doesn’t have the right modules for you… Read more »

sSMTP revaliases, aliases and mail.rc

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I already wrote about sending mails with ssmtp, a simple alternative to sendmail. But since I got a few questions (and I tend to forget myself) how to use ssmtp’s revaliases-file, here is a short reminder: /etc/revaliases, allows you to map a local user to a specific ‘From:’ address on outbound mail and to route that mail through a specific… Read more »

Installing phpMyAdmin on CentOS [Update]

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Because CentOS doesn’t pull all dependencies correctly, here is my little memory hook for installing phpmyadmin (and mysql, of course) After installing the packages, edit /etc/httpd/conf.d/phpmyadmin.conf and add the IP of your admin workstation to the line that begins with Allow from. For using phpmyadmin with cookie auth, you have to set a blowfish secret in /usr/share/phpmyadmin/config.inc.php: Update: Added php-mbstring