Ryan Cartwright's articles

On-line applications "just work"; why worry about the freedom of the licence?

An increasing number of computer users are turning to online applications instead of ones on their desktop. It started with webmail and has moved to productivity/office tools. With the emergence of online applications that have no desktop equivalent, and mobile devices that are browsers in your pocket, things are looking up. But what about free software? If the software we are using is not run on the computer on our desk/lap/hand what does the licence matter? For some time now I've been reading predictions where the browser will be the computer. Does this future have space for free software?

Why I choose copyleft for my projects

Terry Hancock seemed to raise a few hackles when he presented case recently that "copyleft has no impact on project activity?!)". I'm not certain why, because it seemed he was just asking a question really (you'll note the question mark). In that piece he mentions the reasons developers choose a copyleft licence. As a -- somewhat small-time -- developer of free software this topic interests me. Terry made a few statements about why developers choose a copyleft licence as did Tony Mobily in his editorial for issue 20. So let me tell you why this developer chose (and continues to choose) a copyleft licence?

Spam prevention with Exim and greylistd - Part 2 - management and stats

In part one of this tutorial looked at installing and configuring greylistd alongside Exim to help combat the evils of Spam. In this second part I will look at getting some information out of greylistd -- handy if you need to troubleshoot why the CEO's "urgent" message hasn't arrived yet!

Spam prevention with Exim and greylistd - Part 1

Traditional methods of spam protection involve using Bayesian detection rules (usually via SpamAssassin) on messages after they have been accepted by your server. Most mail sysadmins may have encountered the constant cries from their users asking "can't you stop them sending it?". Of course you can't stop somebody sending a message but you can stop accepting them in the first place. Enter greylisting.

These two articles are kind of follow-ons to my previous article on spam prevention in exim mail servers. Think of it as an appendix. If you are starting from scratch you might find is useful to go and read that first.

Inkscape tutorial: creating a simple ribbon

Inkscape is one of the most popular free software vector drawing applications. With minimal effort you can achieve some excellent results. However, for the inexperienced it can be a bit hard to find out how to get those results. In this tutorial I'll look at creating a simple ribbon effect which will hopefully introduce some of the key Inkscape features along the way.

Self-signed certificates and Firefox 3 - a possible solution

Some websites need to handle data securely and assure the end-user they are a) secure and b) who they say they are. The traditional way to achieve these is via Secure Socket Layer. Firefox 3 changed what happens when a self-signed SSL certificate is encountered. It's a change which has caused some concern and much discussion.

Should we only trust certificates signed by third parties? Are there cases where using a self-signed certificate is valid? Should users be informed or warned and how strong should the language of that notification be? Is it possible a simple solution is already available but has been overlooked in all the flan-flinging? I think so.

Smail - the lighter mail server

When most people install a free software mail transport agent (MTA) they plumb for Postfix, Exim, qmail or Sendmail. Whilst these are all fine, they can be a little over the top for some smaller systems or systems where all you need is some kind of local MTA functionality. In these cases many people will install their favourite MTA anyway -- but there are more lightweight alternatives. Here I look at one of them: Smail.

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