Coding

TTFB aka first-byte time is nothing but the time taken by the first byte to reach the client machine when the client seeks a response from the server after the browser running on it makes an HTTP GET request. A small TTFB value indicates that your web server is fast. A high TTFB value denotes that your site is slow in responding to the browser’s HTTP GET request. To fix the problem, you’ll have to work on the code or check web server and DB configuration. ...

If you’re a regular reader of this blog, you may have noticed that this site was throwing error establishing database connection or internal server errors last week. The issue which was caused by the Linux out of memory manager has now been fixed, and the site is now live 24 x 7. I’m using this server to host some other WordPress websites as well. Fixing the error was a very confusing task for me. To be honest, I didn’t know about OOM process killer in Linux. If I knew how this module worked, the error would have been fixed on the day the error message appeared the system log file. ...

Since two weeks, my website was frequently crashing because the MySQL server stopped abruptly at random times of the day. This issue started when I was on a holiday. My site was down for several hours. I configured crontab to start MySQL server when the service had stopped. This didn’t help. I enabled query cache to reduce the load on the server. I use NGINX Fast CGI cache, APCu, and OpCache for my sites. Thus, I didn’t felt the need to install a caching plugin for my WordPress blog. ...

The dreaded WordPress white screen of death means something has gone wrong and is preventing your website from loading. In most cases, the white screen of death will prevent both the front and back end from loading correctly and all you can see is a blank white screen in your web browser. The white screen of death is often caused by a faulty plugin or theme. In some cases, corrupt files, a database error, or a hosting issue could be the cause of the problem. ...

All my websites are hosted on an unmanaged VPS. The VPS has enough of RAM and a decent CPU. It can handle ten high traffic blogs. I had never faced any problems until last week when my website started displaying error establishing a database connection to the visitors instead of the content. This error was reported after I changed one of the table’s structure. Why the heck did I change the structure? Last week, I noticed Yarpp plugin displayed a message that I need to replace the table structure of my post content table from INNODB to MYISAM so that the plugin can display highly relevant related posts. So I changed the structure of my website’s DB table. ...

The use of malicious code attacks against web applications and more specifically, web enabled databases, is on the rise and continues to be a greater threat as systems become more complicated and reliant on third party libraries and frameworks. There are many different types of exploits and vulnerabilities associated with malicious code attacks which can potentially threaten the very databases that power such applications. Several areas of vulnerabilities are discussed below. ...

SQL injection has been a method of attacking databases through multiple tiers of application infrastructure for many years, MacVittie (2008). SQL or Sequential Query Language is a database language used to interact with large quantities of data, typically stored in tables inside a Relational Database Management System (DBMS). Each command using the SQL language typically generates a result set of data. An example of this follows: select * from accounts The (*) is effectively used to return (all) columns of data in the ‘accounts’ table. A similar, and more dangerous statement could be issued using the drop command: ...

The Internet has brought us a wealth of conveniences and everyday tools that we could not live without and more importantly a dependency that we cannot break. In the workplace the Internet has become a part of our day to day lives. We rely on instant communication with our co-workers, friends and colleagues as well as access to a multitude of information at our fingertips. Children from younger ages are becoming more involved with computers and technology in a trend will continue as the Internet of Things evolves around us in every day appliances. Unfortunately, with all these convenience come challenges and risks that we need to deal with. ...

Software Setup For this class you will require three main applications, a text editor, an SSH client and an FTP client. A text editor will be used to write your HTML documents. SSH (Secure SHell) is a text based application which will enable you to setup your Nova web server account, which we will be using to host your web pages online. Finally an FTP (File Transfer Protocol) client will be needed to actually copy over or upload your files to Nova from your PC or Mac. I am recommending your install Atom for text editing, FileZilla for FTP, and PuTTY SSH client for Windows users. ...

Nova is a Unix based web server which is used through various computer studies courses at UMUC. If you are taking one of my web design classes or are enrolled in another UMUC class that uses Nova, the information provided here should be helpful. Nova is the server you will be using to setup your web directories for publishing content online. In order to set up a Nova account you will need you MyUMUC login and password. Once created you will be assigned a unique Nova login account. ...