The Linux operating system that the department recommends for people
to use is CentOS. If you are familiar with Red Hat Enterprise
Linux, CentOS is virtually identical to RHEL (it is built from the
same sources as RHEL). CentOS can be downloaded from
http://www.centos.org. If you have computers running Red Hat Enterprise Linux that you
installed back when the department had a site license for Red Hat
Enterprise Linux, you can convert those systems to CentOS fairly
easily, without having to do an operating system re-installation.
This will ensure that you continue to be able to get security
updates as required by the campus minimum network security
standards. Converting an existing RHEL system to CentOS is not very difficult,
though it will require downloading software packages manually and
modifying your system configuration. The process is basically:
- DO NOT perform a final update with RHEL!
This is especially important for RHEL 5, as RHEL 5.2 will
not down-convert to CentOS 5.1. This will be less of an issue
once CentOS catches up to the RHEL releases.
- Download and import the CentOS RPM GPG public key.
- Download necessary CentOS replacement packages.
- Remove specific packages from the Red Hat system.
- Install the CentOS packages.
- Reboot the system.
CSEHelp has been steadily converting all the department servers from
RHEL to CentOS over the past several months, and these procedures
have been tested many times. If you do run into any problems, feel free to contact CSEHelp for
assistance. Conversion Script
CSEHelp is providing a
conversion script
to assist with the conversion from RHEL to CentOS in a simple,
automated fasion. This script will need to be downloaded to the
machine you wish to convert, and must be run as root.
Additionally, the system you are converting must have internet
access, minimally on the UCSD private networking (172.*). The script will, by default, use the on-campus CentOS mirror to fetch
the software packages it needs, but this can be changed by changing
the "centos_mirror" variable at the top of the script. We've tested the script on both Red Hat Enterprise Linux 4 and Red
Hat Entperprise Linux 5 systems, and have had successful conversions
to CentOS in both scenarios. However, if you have installed
third-party packages either manually or via non-Red Hat
repositories, you may run into problems that the script cannot
account for. This is primarily an issue if you installed sqlite
or yum. If the script discovers a package dependancy problem,
it will alert you before making any configuration changes to your
system.
Performing the Conversion Manually
The instructions are
slightly different depending whether you are using RHEL 4.x or RHEL
5.x.
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