A machine on my network was producing lots of outgoing traffic and I needed to track down what it was up to by getting the destination IP addresses from my router log and doing a whois lookup.

Some whois services are better than other. A good one is at DomainTools:

http://whois.domaintools.com/ 

You can use this by just sticking the IP address you want to check on the end of the URL. For example:

http://whois.domaintools.com/212.58.250.36

After reinstalling Windows recently I found I had a problem accessing the Internet. The problem was DNS-related because pages loaded incredibly slowly but, provided they didn't time out first, would eventually load. I realised that turning off my SmoothWall Web proxy solved the problem, but without the Web proxy I couldn't use Dan's Guardian.

Dan's Guardian is a content filtering service that can be installed as an add-on to SmoothWall. I have SmoothWall running on an old PC, behind my Sky router, as an always-on firewall for my home network. Because I have two kids, I want to filter Internet content and Dan's Guardian does a pretty good job of this. I like it because it's very configurable and allows me to determine the level of filtering, specific sites or domains to block, exceptions to filtering, types of files to block and so on. However, Dan's Guardian relies on transparent Web proxying being enabled, so I need to have that turned on:

Anyway, I couldn't figure out what the problem was until I eventually found a page on the SmoothWall Support site called "Using ident on Windows XP - common problems", which says:

Ident is a service running on port 113 and as such, port 113 needs to be opened on the workstations, in order for ident to be able to server the username. If the built-in firewall is enabled on any Windows operating system, it needs to be configured to allow access to port 113. This can be done using a log-in script or by manually configuring the Windows firewall software. Please refer to the Windows documentation for information on how to do this.

And then a lightbulb went on and I remembered that I'd previously had Windows Firewall turned off. Sure enough turning it off again solves the problem and lets me access the Internet via the transparent proxy. But, as the quote describes, you can run Windows Firewall so long as you add port 113 as an exception. To do this, go to Control Panel, open up Windows Firewall, click the Exceptions tab:

Click the Add Port button and add port 113, with a description:

If you're like me, you have subscribed to lots of blogs and other RSS feeds, and these are all stacked up in your feed reader. If you're really like me, you hardly ever use your feed reader because there's so much in there and you just know you'll never have time to read it all.

But sometimes you come across a blog that you really do want to keep up with. The answer may be to get emailed each time the author posts a new entry. Many sites have a little form to make this easy, but you can set this up for any RSS feed by using FeedBlitz from FeedBurner.

 
First get your RSS feed URL. For example, the RSS feed for this blog is:
http://www.itauthor.com/feed 

Now take the following partial URL:
http://www.feedblitz.com/f/f.fbz?Track=

and add the RSS feed URL at the end. For example:

http://www.feedblitz.com/f/f.fbz?Track=http://www.itauthor.com/feed

Paste this into the address bar of your browser, hit Enter and just fill out the form at FeedBlitz.

Podcast: Play in new window | Download

If you develop Web pages and you need to see what's actually in the traffic to and from the browser, you'll want to check out Fiddler. Fiddler is a really useful free add-on for Internet Explorer. It's particularly useful if you're developing Web applications that use AJAX, or if you want to investigate what actually gets sent to the server when you fill out an online form, or if your PC starts running slowly and you want to check whether there's lots of HTTP traffic going on that you weren't aware of. I found it interesting, and not a little alarming, to see how often passwords I type into a browser are sent up to the server as plain text that anyone along the way could read using a packet sniffer.

Take a look at the Quick Start screencast from fiddlertool.com:
 
This video is hosted at: http://www.fiddlertool.com/Fiddler/firstrun.asp

If, when you browse to a PHP page, you just see the text of the PHP script, it means the server knows nothing about PHP. To it the PHP script is just a text file, so it sends you that, like it would a .txt file.

If, however, you get a blank page, it suggests the Web server knows that .php files should be served up like Web pages, but the PHP isn't being handled properly.

On Apache, the most likely cause - or at least the first thing you should check out - is that the httpd.conf file hasn't been updated properly to point to the PHP module. Make sure this file contains LoadModule, AddType and PHPIniDir statements such as the following (these are for an XAMPP installation of Apache/PHP on Windows):

LoadModule php5_module "c:/xampp/php/php5apache2_2.dll"
AddType application/x-httpd-php .php
PHPIniDir "c:/xampp/php"

If these lines are in the httpd.conf file, the problem may just be that the file hasn't been read since the change was made. Restart Apache and the changes in the file will be applied.