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Configure a Host ISO-based Package Repository on a CentOS 7.2 VM

In a recent blog post, I demonstrated how to set up a local RPM repository (repo) in a VMware CentOS 7.2 VM (AKA guest) running under VMware Workstation (AKA the host.) This made the CentOS VM independent of the need for network access w.r.t. RPM package installation. However, the trade off for the ability to install packages without Internet access is the 6 GB plus increase in the size of the VM necessitated for storing all the packages and metadata. Consider the following alternative scenario. You have downloaded the CentOS-7-x86_64-Everything-1511.iso from the CentOS Project or a mirror, used the ISO

RHCSA Preparation - Script to Configure a Simple OpenLDAP Server

The ability to quickly configure an LDAP (Lightweight Directory Access Protocol) client for accessing user and group accounts is one of the skills you are expected to have when you sit the Red Hat RHSCA exam. LDAP is a application-level protocol for accessing and maintaining distributed directory services over an IP-based network. It is specified in a series of RFCs (Request for Comments) using ASN.1. The latest LDAP specification is Version 3, published as RFC 4511. Typically, at a minimum, LDAP is used to facilitate centralized user and group account administration. Instead of storing user and group account information locally

My Thoughts on Systemd on RHEL7

From the earliest days of systemd, I have been opposed to the technology as far as it’s use on enterprise servers is concerned. Now that RHEL7 (Red Hat Enterprise Linux v7), which uses systemd instead of upstart, is starting to replace older versions of RHEL in enterprise and DOD environments, I thought I would revisit the issue. My technical reasons for opposing systemd on servers are as follows: There is no guarantee that services will be started in the same order each time a server is rebooted. Logs are binary, non-transactional and in a different format than previously. This means

IPv4 Link Local Addresses in Fedora

A network link-local address is an address that is valid only for use within the network segment or the broadcast domain that a host is connected to. Link local addresses can be layer 2 or layer 3. For example, a 48-bit Ethernet MAC address is one form of a layer 2 link-local address. Link-local addresses are generally not guaranteed to be unique beyond a network segment. Because of this, layer 3 switches (routers) do not forward packets with layer 3 link-local addresses. For Layer 3 IPv4 link-local (IPv4LL) addresses, RFC3927 specifies the address block 169.254.0.0/16. Zero-configuration Networking (zeroconf) is a

Revisiting Systemd D-Bus Interfaces

In a May 2013 blog post I examined the then systemd D-Bus interface. At that time the systemd version string was 208. In this short blog I will discuss hostnamectl/hostnamed and timedatectl/timedatectl functionality as it relates to the systemd Dbus. You can use the following dbus-send command to find out what’s available on the D-Bus system bus: # dbus-send –system –print-reply –dest=”org.freedesktop.DBus” \ /org/freedesktop/DBus org.freedesktop.DBus.ListActivatableNames method return sender=org.freedesktop.DBus -> dest=:1.137 reply_serial=2 array [ string “org.freedesktop.DBus” string “org.freedesktop.login1” string “org.fedoraproject.Setroubleshootd” string “org.freedesktop.machine1” string “org.freedesktop.ColorManager” string “com.redhat.problems.configuration” string “org.freedesktop.systemd1” string “org.freedesktop.Avahi” string “org.freedesktop.PolicyKit1” string “org.freedesktop.ModemManager1” string “org.bluez” string “org.freedesktop.hostname1” string “org.freedesktop.NetworkManager” string