Linux Admin Zone

MySQL Cluster is used to provide high-availability, high-redundancy for the distributed computing environment. You might know that beginning with MySQL 5.1.24, support for the NDBCLUSTER storage engine was removed from the standard MySQL server binaries built by MySQL. Therefore, here I’m using MySQL Cluster edition instead of MySQL Community edition. I’m using 3 servers (1 Management and 2 data) to setup cluster in CentOS 5.4 Linux box. The steps mentioned here can be used for quickly deploying a cluster and worked out for me but no guarantee that this will work for you, So its always advisable to go through official MySQL guide as well for production environment. In case you are also riding on cloud computing wave, I’ve already blogged way to setup MySQL cluster in Amazon EC2 environment.

Here’s small bash script to backup important log files from a server to a backup server. You should customize it per your environment. I’ve deployed this script in some hosts and its working fine for me but I’m not making any guarantee that this will work for you as well.

Task: Two most imporant log files in any Redhat based distro is /var/log/secure and /var/log/messages. These are basic log files and there are more log files when your server perform additional roles such as a database server, web server, mail server etc. You can look log files of other installed softwares also and add them in this script to backup them. I have a separate backup server where I want to transfer my log files after compressing them. You can transfer them in some location in case you dont have a separate backup host or environment.

Isn’t this weird? most people ask how to configure a mail server for secure smtp but one of my friend told me that he has a server which running Exim mail server on both port 25 (normal) and port 465 (secure smtp) now he is facing difficulties because the SSL certificates which Exim uses are expired. He wanted to close port 465 without affecting port 25 used by their scripts.

Here’s what I did and worked but if you have better idea or something to add, I’ll be glad to hear.

You need to disable SSL ver 2 and enable SSL ver 3 in apache for PCI compliance. Its very easy to do. Following settings will set SSL ver 3 and also disable older/unsecure cipher suite in Redhat/centos/fedora Linux server:
1. Open /etc/httpd/conf.d/ssl.conf and add or if these lines already there, edit them as per follows:

## Disbale SSLv2 and enable SSLv3
SSLProtocol -All +SSLv3 +TLSv1
SSLCipherSuite HIGH:!SSLv2:!ADH:!aNULL:!eNULL:!NULL

2. Reload httpd service to apply the new settings:

# /etc/init.d/httpd reload

3. Verify the settings by connecting to SSL ver 3 protocol:

One of my friend requested to setup two independent MySQL DB servers in his CentOS 5.4 server box. One MySQL (5.0.77) service was already running on the machine, So I had to install another one. Though, I dont recommend running multiple instances on a single server, instead due to cheap hardware you may better setup a MySQL cluster for best performance. In this case, after initial investigation, I’ve found that there are few ways to implement this. The idea of using MySQL Sandbox interested me most. At the end of day, there was two server running simultaneously on the using different ports for connections. Here are the steps, I took to install and configure multiple MySQL servers: