This article explains how to use SUDO without being prompted for the password. We can restrict which users and/or groups can do this. As root, edit the file “/etc/sudoers”. Add the line: agix ALL=(ALL) NOPASSWD: ALL The above means that the user “agix” can use sudo without being prompted for
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Using Varnish to “Cap” Server Load – Redhat/CentOS
This article demonstrates how to Cap or Limit the load on a Web Server using Varnish. The idea here is to specify a timeout value which, if exceeded, the web surfer will be diverted to a customised error page. By adjusting the timeout value, the administrator can choose what kind
Read moreInstall Cobbler on CentOS/Redhat
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 =
Read moreVarnish 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 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 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
Read moreMySQL Database Replication Example
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
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