Disabling IPv6

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system configuration - Red Hat based systems

The requirements and recommended techniques for disabling ipv6 have changed frequently.  Much of the advice found online today is either outdated or simply bad advice.  Some of suggestions may work with some versions of an OS under certain configurations but not others.

If you do not need IPv6 support and are determined to disable it the following should work for most versions and configurations of RHEL5 and RHEL6.  The appropriate approach is to administratively disable IPv6.  As a general rule, you should no longer try to prevent the IPv6 module from loading since it is a dependency for a number of other components (e.g., bonding).  In fact, as an aside, with some distributions and builds IPv6 is no longer a separate module but part of the kernel.

Any potential change should be carefully reviewed and evaluated before being implemented and confirmed following patching or upgrades.

Requiring Password to Access Single User Mode

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system configuration - Red Hat based systems

Prior to Fedora 19 Red Hat systems did not require a password for single-user mode access by default.  The following covers the procedure to require a password for single-user mode access on earlier Red Hat systems.

Changing Hostname on Red Hat & Fedora

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system configuration - Red Hat based systems

For many years Red Hat systems have used the same approach for configuration of the hostname.  Starting with RHEL 7 and Fedora 18 there is a new procedure for changing the hostname that represents a significant break with this tradition.  There are now multiple hostname classes and a new command to manage them.  This new password scheme is a component of systemd.

The legacy and new configuration procedures required to make a permanent hostname change on current Red Hat and Fedora systems is covered below.

How to Disable CTRL-ALT-DELETE

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system configuration - Red Hat based systems

The behavior of CTRL-ALT-DELETE is determined by the system initialization process.  There have been significant changes in how system initialization and management has been implemented in recent years.  There are 3 seperate implemenetations in use on current Red Hat based systems.  The oldest is SysVinit, the traditional System V init process, which is used on RHEL5.  On RHEL6 this was succeeded by Upstart.  Upstart was replaced with systemd in recent Fedora releases and RHEL7.  The procedure to disable CTRL-ALT-DELETE for each of these is summarized below.