If you're maintaining multiple Red Hat Enterprise Linux systems (or equivalent offsets like CentOS or Scientific Linux) your administration work with the particular hosts will gain in a routine. Because even the best administrator might forget something it would be advantageously to have a central software and …

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Every VMware administration knows the following issue - the cluster needs to patched and so the particular nodes need to be rebooted. Fortunately this doesn't bother the users working on the farm becuase the virtual machines can be moved "online" between the cluster nodes. There might be a little show stopper when ISO …

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It is often unjustifiable said that implementing high-availability under Linux is way too complex. Of course you will have to be patient while spending some time in learning the required basics - but all this is feasible for an experienced administrator (or someone who wants to be such an administrator some day). This …

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OpenVPN Connect is a good OpenVPN client for iOS devices with version 5.0 or higher. Using this app VPN tunnels can be managed and used comfortably. Unfortunately the respective OpenVPN configuration files can't be edited directly on the iPhone, iPod or iPad like in the Android application. The first setup might be …

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On RHEL or CentOS 5.3 it is possible that a noticed default gateway is ignored. In this case the routing table doesn't contain any appropriate entry... 1# netstat -r|grep default ...even if the gateway was noticed both in the main network configuration... 1# cat /etc/sysconfig/network 2... 3GATEWAY=10.24.36.1 ...and …

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Many administrators or IT enthusiasts still might know Common Desktop Environment (CDE) from old UNIX days. Introduced in 1993, it was Unix's standard desktop for HP-UX, IBM AIX, Sun Solaris and Tru64 for more than 10 years. Even if Solaris dropped its CDE support 3 years ago, the old desktop is still used in HP-UX, …

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nslookup and ifconfig are two well-known tools for configuration the network of Unix/Linux hosts and checking whether DNS is working properly. ifconfig was part of the 4.2BSD distribution in 1983 for the first time and quickly became the standard tool for network configuration - even commerical Unices like Solaris or …

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. Meanwhile there are plenty of operating systems available for the Raspberry Pi - including an ARM version of the source-based Linux distro CRUX. So if you like handcrafting or think Raspbian is "too mainstream", you can have a lot of fun with a SD card with at least 1 GB of memory and a pot of coffee. 😉 Partitions …

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If you install and configure a Postfix mail server for relaying mails using an external smarthost you might be puzzled about the following error message: 1Mar 19 17:00:22 hostname01 postfix/smtp[2003]: warning: SASL authentication failure: No worthy mechs found The reason for this issue can be really trivial - in my …

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Hint: The following issue has been fixed by a RHEL / CentOS patch (util-linux-ng) - just update your system! If you want to install Open Monitoring Distribution on RHEL or CentOS 6.4, you might have the problem that creating sites isn't working as expected: 1# omd create test 2Adding /omd/sites/test/tmp to /etc/fstab. …

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