To display a message to all users who log into your server, you should edit the file “/etc/motd” as root. #### This is the Web Server for AGIX. #### Note that this message is displayed ‘after’ someone has logged in, not before. Nothing further needs to be done. Just try
Read moreAuthor: Andrew Galdes | Principal Consultant
A Linux and Cybersecurity expert in Australia.
RHCE, Linux+, Sec+, CySA+, SecurityX, CISM, CRISC
Sudo Without a Password & Restricted Commands/Groups – CentOS and Redhat
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
Read moreUsing 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 moreInstalling Debian on a Raspberry Pi using a Mac OSX
This article explains how to install Debian on a Raspberry Pi. You will need to download the Debian distro prepared for the Pi. Get it from here: Downloads TIP: Use a fast SD card. They come rated: Class Minimum Speed Class 2 2 MB p/s Class 4 4 MB p/s
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 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
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