Category: "HTTP/SSL"

Live HTTP Header tracking for Firefox

Live HTTP Header tracking for Firefox

LiveHTTPHeaders is a FireFox extension that lets you look at all HTTP headers for all requests issued by the browser.

I am updating and resurfacing this post today since -- after a long while of being mildly maintained -- this fine plugin seems to have effective backing again. Version 0.17 works on FireFox 9.x.

Even in the days of FireBug, LiveHTTPHeaders is still an irreplaceable tool in a web developer's toolkit. As a matter of fact, LiveHTTPHeaders is the best way to track chains of redirects, which FireBug doesn't display right, as it will often clear the "Net" tab from one request to the next.

The header tracking window can be opened through Tools > Live HTTP Header. It will then capture all requests and display HTTP headers being sent as well as headers being received. Note that it is possible to stop capture at any time so the display stops scrolling. It is also possible to filter out specific requests (for example images) with a regular expression (regexp).

The extension also extends the Page Info windows with a Headers tab, which is useful if you just want to see the headers for the current page.

Finally, it's also possible to edit requests and replay them again, modified. At this time this is still in beta though, and Tamper Data may be a better extension for that purpose.

How to log request processing times in Apache

If you have an apache (2) web server, you probably have an access.log file showing you all kinds of data using the “combined” log format. Let’s see how to include processing time into that log file.

By default a line in the combined log looks like this:

[codeblock lang="” line="1″] - - [03/Dec/2009:03:20:47 +0100] “GET /info-tech/ HTTP/1.1″ 200 46482 “” “Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv: Gecko/20091102 Firefox/3.5.5″[/codeblock]

Notice the 2 dashes - - just after the IP. The first one stands for “I could not identify the user using ident” and the second one for “no user authentication was performed".

Now, let’s face it: you will never identify anyone using ident. Your apache conf probably even doesn’t try. That field is a left over from ancient times. So let’s replace that first dash with something useful, i-e: the processing time of the request! Note that by doing this we keep the global structure of the file identical and any log processing tool you might be using should not be affected.

Full story »

The importance of URIs

“People don’t recognize how important URIs are. The notion that you have a huge, world-scale, information space, and that everything in it has an name and they’re all just short strings that you can paint on the side of a bus; that’s a new thing and a good thing.”
Tim Bray

How to redirect to (or reverse)

Most sites can be reached by two different URLs. For example and .

This is good for the users who can choose whether or not to type in the "www." part. However, it is not good for search engines which will tend to see a lot of duplicate contents.

If you are on an Apache webserver, you can use mod_rewrite in order to redirect all traffic that goes to the www.domain to the "non www" domain. (If you want it the other way round, see below)

Try adding this to a file named ".htaccess" at the root of your site (create that file if it doesn't exist):


RewriteEngine on
RewriteCond %{HTTP_HOST}   !^$
RewriteCond %{HTTP_HOST}   !^your-domain\.com [NC]
RewriteRule ^/(.*)         http://your-domain\.com/$1 [L,R=301]

Note: More advanced users will prefer to add this to the httpd.conf / apache2.conf instead in order to gain a little efficiency and also to not interfere with tests on development/staging servers.


RewriteEngine on activates mod_rewrite.

The first RewriteCond makes sure we have a non(!) empty(^$) hostname to work with.

The second RewriteCond detects that the host name is not(!) the one we want (e-g: it has an extra www. part in it).

The RewriteRule sends out a permanent(301) redirection to the right domain name followed by the currently requested path/page ($1).

Handling multiple domains at once

Below is more elegant (yet complex to read) solution that can handle multiple domains at once (if you have "ServerAlias"es) and that doesn't require to type-in your domain (just copy/paste):


RewriteEngine on
RewriteCond %{HTTP_HOST}   !^$
RewriteCond %{HTTP_HOST}   ^www\.(.+)$ [NC]
RewriteRule ^/(.*)         http://%1/$1 [L,R=301]

The trick here is to use %1 which matches the canonical part of the domain name in the second RewriteCond (.+) .

Reverse redirection

By popular demand, here is how to redirect from to


RewriteEngine on
RewriteCond %{HTTP_HOST}   !^$
RewriteCond %{HTTP_HOST}   !^www\. [NC]
RewriteRule ^/(.*)         http://www.%{HTTP_HOST}/$1 [L,R=301]

IE 6 not refreshing

Just stumbled upon yet another funky IE6 "bug" (if I may say so...

When you want to automatically refresh to another page, you send a header that looks something like:


The funky thing is that if that header exceeds the maximum size of 263 characters, IE won't do the refresh!

Okay there's got to be a limit, but why so low? And why "263" ??

No need to say, auto refreshes work fine in Firebird with headers much longer than that.

I guess this is why you still need to put some dirty message underneath like 'if nothing happens, please click here! :/

PS: Please don't tell me to use a Location: instead. This would make it impossible to set cookies.