Archive for September, 2014

Resetting the root password

If you ever forget your root password, you can actually reset it with the following steps.

  • Interrupt the boot at the GRUB stage and boot to runlevel 1, AKA single user mode.
  • Interrupt GRUB by typing a character such as “space” then append to the kernel line by typing “a”
  • Backspace through “rhgb quiet” and append ” 1 “
  • Then hit <enter>

This will give you a root shell and not a login prompt. From there you can use the “passwd” command to set a new root password.
Other user passwords can be reset, and other administrative tasks can be performed as well. Exiting the single user root shell will boot to the multi-user mode defined in /etc/inittab.

CentOS-6 Note: Due to an upstream SELinux bug the root password cannot be reset on a fresh install of CentOS-6 without an additional step. Booting with “selinux=0” appended to the grub kernel line, or doing “setenforce 0” after logging in and before attempting to reset the password are work-arounds.

(If SELinux is enforcing then do not forget to relabel your filesystem afterwards or you will not be able to login until you reboot and repeat the instructions and include the autorelabel)

 From: http://wiki.centos.org/TipsAndTricks/ResetRootPassword

2014
09/22
CATEGORY
Linux
Security
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Install MySQL 5.5 on CentOS/RHEL 6.5 and 5.10 via Yum

Redhat Enterprise Linux (RHEL) 5.x and CentOS 5.x have been providing MySQL 5.0 in it’s distribution since that was the active stable branch when RHEL 5.0 was released on 14th March 2007 (CentOS 5.0 on 12th April 2007). Since then, Sun/Oracle have released MySQL 5.1 and MySQL 5.5, so the Webtatic Yum repository has added them to it’s web stack, which now provides updated versions of all the AMP in LAMP.

Update 2014-03-01 – mysql55 packages have been renamed to mysql55w packages (as well as mysql51 to mysql51w). This is to ensure it doesn’t clash with SCL packages.

First, to set up the yum repository, install the webtatic-release RPM based on your CentOS/RHEL release:

Webtatic EL6 for CentOS/RHEL 6.x

rpm -Uvh http://mirror.webtatic.com/yum/el6/latest.rpm

If you already have MySql client or server installed (rpm -q mysql mysql-server), then you can upgrade using the following method:

yum install mysql.`uname -i` yum-plugin-replace
 yum replace mysql --replace-with mysql55w

“yum install mysql” is only there to make sure yum-plugin-replace can resolve dependencies correctly if only mysql-server was installed.

Otherwise, to install MySql client and server, then run:

yum install mysql55w mysql55w-server

You should upgrade existing tables before setting the server to become a production machine, which can be done by starting the server and running the mysql_upgrade script (this may take time depending on the size of the database).

service mysqld start

# This will issue a password prompt for the user. If you don’t have a root user password, remove the “-p”
mysql_upgrade -u root -p

MySQL 5.1

The Webtatic 5 repository for CentOS/RHEL 5.x includes mysql51-* packages for installing MySQL 5.1. This can be installed by replacing in the above commands “mysql55w” with “mysql51w”.

As MySQL 5.1 is standard in CentOS/RHEL 6.x, it is not included in the Webtatic EL 6 repository.

2014
09/12
CATEGORY
Linux
MySQL
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