How to Avoid SYN Cookies DOS Attacks

SYN Flooding is the most common DDOS attack. I have tried to explain some tweaks through which you can avoid these attacks.

Troubleshooting Linux Filesystem Issues

At any moment a system admin may come across file system failures due to issues with data structures (or objects such as inode, directories, superblock etc. This can be caused by any reason:

  • Buggy device driver or utilities (especially third party utilities)
  • Mistakes by System Admin
  • Kernel bugs

Due to Filesystem Failure:

  • File system will refuse to mount
  • Entire system get hangs
  • Even if filesystem mount operation result into success, users may notice strange behavior when mounted such as system reboot, gibberish characters in directory listings etc

How to install memcache

In the beginning we need to install libevent because of memcached dependency

Check if libevent is installed or not?

MySQL Master-Slave Configuration

In this tutorial, I have only shown the commands to configure Master-Slave replication as the details, pros/cons of the setup is available throughout the web.

Enable HTTP Compression in lighttpd

Compression can save your valuable bandwidth & helps your site load faster on client’s end. However on the other end it takes little extra resources of your server.

Generating Public/Private Key Pair for PKI Access

Preliminary Setup

Setting up public key authentication to access a particular remote host is a one-time procedure comprising three steps.

Converting Amazon EC2 Instance-store instances to EBS instances

The biggest reason most of us switch from instance store to EBS backed instance is that S3 backed (instance-store) images are not persistent i.e. they can loose the changes when rebooted whereas EBS provides “block level storage volumes for use with Amazon EC2 instances.”.  The other basic differences are:

Configure Lighttpd with chroot Jail Environment on centos-5 Machine

Common Information: chroot jail directory /webroot lighttpd document root /webroot/var/www/lighttpd

1. Install lighttpd, php and mysql server

SSH with chroot Jail

There are numerous times when we sysadmins are asked to configure SSH access for restricted users in chroot jail environment. In this tutorial I have tried to explain the configuration of SSH in chrooted environment.

Pros & Cons of WordPress Multisite

Are you running multiple stand alone installations of WordPress sites for either yourself or clients? Sick of having to log into each site every time there is a core update or plugin/theme update to apply? Then multisite may be your answer. WordPress 3 has made it possible to host multiple domains within one installation of wordpress. While, in theory, this sounds like a plus, but there are many pros & cons of it and you should seriously consider them before jumping in to hosting multiple domains on your single WordPress installation.