This article explains the installation process for Cobbler on CentOS 6.4 64bit. Install Cobbler and the other services. TIP, you need the EPEL repo available: yum install cobbler* tftp* httpd Edit the “/etc/xinetd.d/tftp” file to enable the TFTPd service: service tftp { socket_type = dgram protocol = udp wait =
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Varnish Cache as a Load Balancer on CentOS/Redhat
This article explains how to configure the Varnish Cache as a load balancer. In other words, you have two Web Servers with a Varnish server in-front of them. As illustrated below: Internet -> Varnish -> Web Server 1 -> Web Server 2 Varnish does it’s load balancing in a round-robin
Read moreBackup all MySQL databases into their own backup file
This is an example Bash script that will backup the MySQL databases on the local system. It will backup all databases except those called “Database”, “information_schema” and “mysql”. In other words, it will backup ‘your’ databases. Just remove those from the “egrep” command if you want all databases (including the
Read morePuppet err: Could not retrieve catalog from remote server: hostname was not match with the server certificate
This article explains the error “err: Could not retrieve catalog from remote server: hostname was not match with the server certificate”. This error suggests that the Puppet servers SSL certificate’s name is not when the Puppet client expect. On the Puppet server, issue the command: puppet cert print $(puppet master
Read moreInstall Puppet Server & Client on Redhat & CentOS 6
This article explains how to install the Puppet server (also known as the PuppetMaster) and client on a Redhat or CentOS server. Note that Puppet uses TCP ports 8140, 61613, and 443. First add the Puppet repo on both the puppet client and server systems. The following link has several
Read moreConfigure Varnish Cache for Multiple Domains – CentOS/Redhat 6
This article applies to Varnish 3. This article explains how to configure the Varnish Cache to cache for multiple domains on the same backend server. I’ve used CentOS 6.2 for this example. In this example, Varnish is listening on TCP port 80. The DNS “www” “A” record for the domains
Read moreSpecifying an SSH private key to use on the command line
You can specify which private key to use when issuing the Linux “ssh” command. This allows you to use one of many different private keys depending on which server(s) you’re connecting to. ssh -l agix example1.agix.local -i id_rsa.exmaple1 -v The above assumes that you have a private key in the
Read moreConfigure SNMP on CentOS for use with Nagios (monitor disk space)
This article explains how to configure SNMP for use with Nagios on a CentOS server. It’s assumed you already have Nagios installed but not necessarily configure to use SNMP to monitor a host. We use “Disk Space” monitoring in this article. For this article, i’ve used the following versions: 1.
Read moreInterpreting ADSL SNR and Attenuation Figures
This article outlines what you can expect from SNR and Attenuation figures from ADSL modems. The tables below should be used to assist you in troubleshooting ADSL quality issues – even service drop-outs. Attenuation is the loss of signal in a return trip between your ADSL modem and the exchange.
Read moreStreaming Internet Music for Asterisk 10 “Music On Hold”
This article explains how to add Music On Hold (or MOH) for Asterisk 10. The music will be streaming from the Internet – in this case, the “ABC News Radio” channel/station. Note that the download of Internet radio data starts when someone goes on hold. And stops when they go
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