PayPal Recurring Payment and IPN Variables

This week, I am working on one website project with PayPal Recurring Payment. As the project requirement, I need to use PayPal IPN to track all PayPal transaction. After a few research, I am so surprised that there is not a clear development document to describe the whole flow of PayPal Recurring IPN. It is necessary to write it down about what I have understand. I hope it will be helpful for developers who have the same needs.
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Get My Website Back Into Google Search Engines

This morning, I suddenly find that one of my website disappeared from google search engine. Actually I don’t know when it happened. I have not paid any attention on this website because its traffic is low. There are several reason for low traffic. From google analytics, I can find some organic search from search engine like Bing and Yahoo, but not google. The problem here I mentioned is not low traffic, but there is no traffic at all from google search. Hence, I am doing several testing about my website on google search.

My website is connection-kit.com. It is registered 3 years ago. My website was added to google webmaster tools at that time. The last article I was posted is at July 23, 2013. I have checked in my webmaster tools, Google still crawls on my website every day, and all my pages are still indexed. The following two diagram shows you the last 3 months Google webmaster states.

Google Crawls in 2014
Google Crawls in 2014

Page Indexed in Google
Page Indexed in Google

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How To Avoid Login Page Brute Force Attack

My website is getting extremely slow in this week, so I have spent several days to find out the problems and make some performance tuning in my Amazon EC2 server which hosts my WordPress website. My Amazon EC2 server’s CPU usage keeps reaching 100% but there is not too much traffics.

After checking my Apache log file, I have found lots of POST request to my wp-login.php page, which is the login page of wordpress. All the requests are direct request and look very suspicious. I guess my website is always down because of the continues login attempts, which cause CPU usage to 100%.
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Testing WordPress Website Performance in Amazon EC2

In last post, I have mentioned that I migrate my website from sharing hosting to Amazon EC2 cloud. I spent some time on learning Linux, Apache2 and MySQL configurations. After the website was up, I thought everything was perfect, until I got a warning email from Amazon CloudWatch. The warning email notified me that CPU usage was greater than 75%. And my Amazon EC2 server was getting slower and slower. The worse case was that it hanged for several times.
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Useful Command Line for Working on Amazon EC2 Ubuntu for Apache, PHP and MySQL

In the past few weeks, I am working to migrate our WordPress website to Amazon EC2 Ubuntu system. Even though I have some experience on Linux System, but it is long time ago. I just forget lots of Linux command and it is time to remember. In this tutorial, I will not teach you how to setup the ubuntu in Amazon EC2, or how to set up Apache and PHP5 because there are too many tutorials on internet about that and they are good enough to guide you and me to get our job done.

In this post, I am going to write some basic Linux commands which are quite useful when we are working on Amazon EC2 Ubuntu, especially for Apache, PHP and MySQL. All these commands are used when I am build my Amazon EC2 WordPress website.
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