When you’re developing a large website, you often find yourself with a couple of broken links floating around on your site. As most developers working on dynamic sites generally don’t think about it, your first indication that you have a problem is usually only after deployment.

Either you’re unlucky enough to have it brought to your attention by a customer, or you discover it yourself using a tool like Google’s Webmaster Tools.

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This is exactly what happened to me while working on our new Cape Town Accommodation venture www.stayunlimited.com.

The webmaster tools will allow you to drill into the info and find the offending links. Now you happily go off and fix the problem in your site and deploy again.

But hang on a second. How can you be sure that you haven’t created more broken links in the process of fixing the problem you initially identified? With a dynamic site making heavy use of URL rewriting this is a major possibility (and it happens to be exactly what happened to me).

Obviously you need to test that your site is now broken link free. You can be optimistic about it and wait for Google to re-index your site so you can check the webmaster tools again (probably not a very good idea). Or you can use one of the many online link checkers available to scan your site. But that isn’t that great a solution either, because at this point you’ve already deployed the site.

First prize then would be to check your site for broken links in your development environment before deploying. There are a number of tools available for doing this, but most are commercial and not free of charge. The SoftwareQATest.com website has a number of tools listed if you’re interested.

From their list I discovered the excellent freeware Xenu utility by Tilman Hausherr. This little Windows app will scan through your locally deployed website and highlight any broken links, allowing you to fix them before deploying!

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What more could you ask for?

If you've been following the news of late you'll know all about the concern that the Conficker worm is causing in security circles these days.

Conficker is believed to be the most widespread computer worm infection since SQL Slammer in 2003. The initial rapid spread of the worm has been attributed to the number of Windows PCs (estimated at 30%) which have yet to apply the Microsoft patch for the MS08-067 vulnerability.

By January 2009, the estimated number of infected computers ranged from almost 9 million to 15 million. [Wikipedia]

Due to the advanced nature of the worm, it is very difficult to detect, and I personally don't trust my Antivirus software to do so reliably. The idea of having my computer hijacked as a zombie in a huge botnet perturbs me, so finding out whether my computer is infected is important to me.

There are a number of symptoms you can look out for:

  • Account lockout policies being reset automatically.
  • Certain Microsoft Windows services such as Automatic Updates, Background Intelligent Transfer Service (BITS), Windows Defender and Error Reporting Services disabled.
  • Domain controllers responding slowly to client requests.
  • Congestion on local area networks.
  • Web sites related to antivirus software or the Windows Update service becoming inaccessible.

That last item there has proven to be quite useful, as Joe Stewart of the Conficker Working Group has created an "eye chart" that can easily show you whether you are infected by relying on the worm's habit of blocking access to antivirus sites.

Conficker Eye Chart

Basically he's set up a web page that displays logos directly from a number of antivirus vendor's web sites. If you can't see some of the images, you're probably infected as the worm blocked access to those sites. There is one caveat though: if you use a proxy server the test is useless, as the worm cannot block access through it.

Head on over to the Conficker Eye Chart and check your computer. After all, isn't it our duty to make sure we're not part of this criminal cabal?


I am a software developer / architect currently interested in combining .NET technologies with open-source operating systems. 

I am a member of the open-source BlogEngine.NET development team and focus mainly on ensuring Mono compatibility for the project.

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