New articles on AskFlib.com

Simple Remastering of RHEL / Fedora / CentOS

Fri, 22 May 2009 14:01:24 +0000

It is often the case that you wish to automate some elements of an install CD (or DVD) but don't want to go through all the steps required of doing a complete remaster. What follows is the minimum steps to add (or edit) a couple of files on a CentOS CD.

Passing variable numbers of arguments to functions

Thu, 21 May 2009 05:21:29 +0000

Recently a visitor in my IRC channel came in with an odd problem. He needed to send a variable amount of arguments to a function. The function wasn't under his control, so he was unable to pass an array to it and parse it within the function itself.

PHP as far as I can tell has no easy way to do this. This short article explains one method to accomplish the task.

Generating and Using RSA SSH keys

Wed, 20 May 2009 17:13:44 +0000

Passwords are insecure. Unless you lock out accounts with something like fail2ban, then ssh accounts can and will be bruteforced by malicious attackers. Changing the port from 22 can help, but better still is not using passwords to secure ssh logins. Public key cryptography is the answer.

In this article, I explain how to get up and running with RSA keys in Linux.

Dynamic Buttons with GD and PHP

Wed, 20 May 2009 12:44:12 +0000

On many sites its very difficult to predict exactly which graphics you might need. One answer is dynamic buttons.

Coping with heavy server loads

Wed, 20 May 2009 01:06:44 +0000

Not every site has been dugg or slashdotted, but when they do its a frequent occurance that the server is unable to cope with the sheer number of requests that are fired at it. However all is not lost, there are many little tricks that together can mean the difference between being able to weather the storm or being trampled by it.

Creating business cards with FPDF and PHP

Tue, 19 May 2009 13:31:37 +0000

When I need to create business cards or similar documents, I frequently head for the text editor and knock out a small app. This is one such application.

Making Sessions Cluster-aware

Tue, 19 May 2009 11:33:26 +0000

Once your application scales to the point that a single server isn't able to serve all your visitors anymore, sessions can become a problem.

The default files-based session handler was only designed for a single server and so this must be taken into account if your application is to continue to run flawlessly.

In this article I try to show some of the options available for dealing with sessions in a cluster.

php_value, php_flag, php_admin_value, php_admin_flag

Mon, 18 May 2009 19:47:11 +0000

If you change almost any of the PHP setting in php.ini then you affect all vhosts on the server. This can be a bad thing. Scripts may break and functionality may change.

Luckily, there is a more fine grained solution if you are running PHP as a module.

Useful Datasources

Tue, 12 May 2009 07:31:23 +0000

A site is only as good as the content it contains and reusing existing content in new ways is an easy way to minimise the effort required to produce new applications.

In this short article, I explain a few of the freely available data sources online. Some of these may be covered at a future date in more detail. This is really just aimed as a quick overview.

Securing Variables with Hashes

Mon, 11 May 2009 16:49:17 +0000

Often, scripts need to send data in the url. The problem with doing this is that users may tamper with data possibly resulting in security problems.

In this article, I show you how to use hashes to secure GET variables and other data.