Archive for 2011

Some LVM Notes

A few LVM notes to jog the brain A. Steps to create the logical volume.. List the current physical volumes. In this instance, were interested in a blank 20GB SATA – /dev/sdb. You can extend a logical volume by adding additional phyical volumes later. fdisk -l Disk /dev/sda: 21.5 GB, 21474836480 bytes 255 heads, 63 […]

High Availability Linux Web Server Example

Just a quick example of setting up a Linux HA failover environment for an Apache/MySQL web server. This runs through a Ubuntu installation, however RedHat shouldn’t vary too much. 2.11.1.24 – fixed IP of server1 2.11.1.25 – fixed IP of server2 2.11.1.30 – apache site1 (virtual IP) 2.11.1.31 – apache site2 (virtual IP) Make sure […]

Some NFS Notes

A few notes on configuring NFS on RedHat or Ubuntu The server packages to install are: Ubuntu: apt-get-install nfs-kernel-server nfs-common quota RedHat: yum install nfs-utils nfs-utils-lib quota The client Packages are: Ubuntu: apt-get install nfs-common RedHat: yum install nfs-utils nfs-utils-lib A few things to configure on the server: /etc/hosts.allow Any hosts listed here will be […]

Example IPTables rules for a webserver

Just a quick and basic example IPTables ruleset to secure a web/mail server: # Allow outgoing traffic and disallow any passthroughs iptables -P INPUT DROP iptables -P OUTPUT ACCEPT iptables -P FORWARD DROP # Allow traffic already established to continue iptables -A INPUT -m state –state ESTABLISHED,RELATED -j ACCEPT

Don’t be a Tw@t – Use At!

Sigh today I made a schoolboy error – making config changes to a live firewall on a remote server without giving myself any kind of safety net! Anyway, this is an example of where you should really use something like the at command to bail you out should anything go wrong: get the current system […]

Android Apps for a System Administrator

With phones getting smarter and smarter, its now possible to monitor servers and perform basic administration tasks from your android handset. Here are a few tools I find useful. Connectbot is a great SSH client for the Android. It is fully functional, supporting SSH keys and copy/paste etc.   For Windows RDP connections, I found […]

Screen – Can be useful!

Screen is something I’ve never been interested in using previously, but to be honest, it has many benefits. Screen is basically a window manager that allows you to run many windows from your SSH session. By doing this you don’t need to initiate several SSH sessions to a box when running complex tasks. Also if […]

Install Java 1.6 JRE and JDK On CentOS5

Very busy right now, so here’s a quick and dirty writeup for install Java 1.6 on centos5. To install the JDK yum install -y jpackage-utils wget http://cds.sun.com/is-bin/INTERSHOP.enfinity/WFS/CDS-CDS_Developer-Site/en_US/-/USD/VerifyItem-Start/jdk-6u14-linux-x64-rpm.bin?BundledLineItemUUID=KxWJ_hCuwSUAAAEvTWRZB8TT&OrderID=WeuJ_hCuedUAAAEvLGRZB8TT&ProductID=tPxIBe.oz2IAAAEhmh0zLjfT&FileName=/jdk-6u14-linux-x64-rpm.bin chmod +x jdk-6u14-linux-i586-rpm.bin ./jdk-6u14-linux-i586-rpm.bin

Roll back RPM packages – CentOS/RedHat

Wouldn’t it be useful to be able to easily undo a yum/RPM change that you have just made? Well you can. By default yum/RPM do not save roll back information. This feature can easily be enabled by doing the following, however its not perfect and can use a lot of disk space as its repackaging […]

Your WordPress.com account, xxx is not authorized to view the stats of this blog.

So its fair to say that I’ve been somewhat neglecting this blog – been far too busy in the world of access control software! Anyway, to start with a simple one, I signed into my wordpress account today and noticed that the site stats weren’t working with the following error: Your WordPress.com account, xxx is […]