Category: All Linux HowTo’s

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

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

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

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

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

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.

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.

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

This article explains how to install MySQL 5.1 on Redhat/CentOS and configure replication to a slave MySQL server. In this article, the master host has the IP address “192.168.122.7” and the slave has IP address “192.168.122.6”. Remember to restart the MySQL server if and when you make changes to the