My current employer is under requirement that all on site system administrators be Red Hat Certified. That is actually the reason why I took the RHC in 2006. My employer the time NDS on Har Hoztvim Israel wanted the people supporting customers to have certification. The test they chose was the RHCE. As those […]
Read More →Author: Steven Protter
Maria-db(mysql) two node installation with galera data replication
This is the first step toward unsupported installation of the NDC, New Data Cloud. To get the commercial version with full support, click here. This document takes you through the installation and creation of a two node database installation. This install was done in google compute engine but with the right band width will work […]
Read More →Use TCP wrappers with care
Real life story. DMZ based server dedicated to SFTP was configured with sshd rules in /etc/hosts.allow sshd : ALL@16.89.97.*:ALLOW sshd : ALL@14.251.*:ALLOW sshd : AAL@208.94.61.*:ALLOW Should have been: sshd : ALL@16.89.97.*:ALLOW sshd : ALL@14.251.*:ALLOW sshd : ALL@208.94.61.*:ALLOW That network was the firewall to the outside world. The end users were inconvenienced and the firewall […]
Read More →Quick and dirty autofs script share
I run a large unix and linux server farm on the west coast. In the old days we had problems with scrip versions. The problem was we pushed scripts from a central server and inevitably due to network or space issues the updates did not happen reliably. In 2012 we opened up our unix management […]
Read More →Making sure what is configured to mount is mounted
Here is a script that uses some advanced awk commands to check that what is configured to be mounted in /etc/fstab is actually mounted. #!/bin/ksh ######################################################################### # fsrootreserve #HPUX_SCRIPTS=/opt/depots/scripts/system_build/HPUX #COMMON=/opt/depots/scripts/system_build/COMMON # Load common environment . /opt/scripts/env/.scriptenv.linux # set total variable for reserve blocks tot=0 echo “. Checking mount status of all […]
Read More →Network install point httpd with Centos or RHEL6 using kickstart
Why set up a network install point? So you can do consistent Linux installations. Really so you can do the same installation over and over again and come out with consistent results. Today’s article is how to set up the install point and have it work. There is credit for the source article below but […]
Read More →DNS configuration checklist
BIND has always been a dark art. Recent configuration nuances made in the name of improving security have made things all the more fun. Here is a simple checklist that can avoid trouble and downed websites. Note that on RHEL6/CentOS/ and clones the /var/named/chroot structure has been made obsolete. Before starting cp /etc/named.conf /root # […]
Read More →Centos Continuous Release with caution
Centos Continuous release is very easy to install. Download and install 1 rpm and you are all set. i386: http://mirror.centos.org/centos/6/extras/i386/RPMS/centos-release-cr-6-0.el6.centos.i686.rpm ( sha256: 9fc78d2d79abeb1513f0851d075a2860f5039fc8db3fb0db4c660252fffda894 ) x86_64: http://mirror.centos.org/centos/6/extras/x86_64/RPMS/centos-release-cr-6-0.el6.centos.x86_64.rpm ( sha256: bd55e1505caae2f78c306290d235b7f54833fcad5a9f1942b3cb54e28f7bfe73 ) But I urge caution. In my lab, I downloaded the 64 bit version and installed it. Then I ran the following command: yum -y update […]
Read More →Network Channel Bonding (teaming) RHEL 6.0
This procedure did not actually change very much from RHEL 5.0. Knowing the changes however are pretty critical to getting it right. Gone is the Administrator’s friend and potential cestpool, /etc/modpprobe.conf Its replaced by anything you want to load in /etc/modprobe.d Naming guidelines? Who needs them. Name the file anything you want. Procedure: Still pretty […]
Read More →Welcome to the Linux Authority
This is a magazine dedicated to all things Linux. It is based on my work experience in the Corporate ITspace both in Israel and the United States. Steven “Shmuel” Protter President and Owner, ISN Corporation
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