Archive for the ‘Tutorial’ Category

PGP and SSH keys on a Yubikey NEO

January 2nd, 2015 No comments

With the new year, I decided it was time to make a new PGP key. I wanted to keep this key on a Yubikey NEO and NEO-n for every day use. By using hardware tokens like the Yubikey, the private PGP keys never need to be stored on my computer. The PGP keys on the Yubikey can also be used for SSH public-key authentication.

My current PGP key can always be found at
Read more…

Categories: Tutorial Tags:

IntenseDebate and Google Analytics

February 16th, 2011 22 comments

I use IntenseDebate for the comment system on my blog. I also use Google Analytics to keep stats on how many people visit my site. To integrate the two, I created a Google Analytics plugin for IntenseDebate.  With this plugin, when someone leaves a comment, an event is added in Google Analytics.  This event can then be used with advanced segments in Google Analytics to see metrics focusing just on visits that lead to comments.

To see the IntenseDebate events in Google Analytics, browse to Content -> Event Tracking -> Categories ->IntenseDebate

The plugin is not currently in the approved list of IntenseDebate plugins.  I’d like to do more testing before submitting it.  If you’d like to help test, you can download my IntenseDebate Google Analytics plugin and add it to your IntenseDebate custom scripts.

The plugin can be customized to create a virtual page view if you’d like to create a goal based on comments.  To enable this, add the following to your IntenseDebate custom scripts.

var id_ganalytics_plugin = id_ganalytics_plugin || {};
id_ganalytics_plugin.use_vpage = true;

With this enabled, a page view for /service/IntenseDebate/CommentPosted will be created each time a comment is posted.

The plugin can further be customized to change the event that is tracked and to change the virtual page.  The following options control the event.  See the event tracking overview page for documentation on category, action, and label.

var id_ganalytics_plugin = id_ganalytics_plugin || {};
// Use id_ganalytics_plugin.use_event to enable/disable event based tracking
id_ganalytics_plugin.use_event = true;
// Use id_ganalytics_plugin.event_category to set the event category
id_ganalytics_plugin.event_category = 'IntenseDebate';
// Use id_ganalytics_plugin.event_action to set the event action
id_ganalytics_plugin.event_action = 'Comment Posted';
// Use id_ganalytics_plugin.event_label to set the event label
id_ganalytics_plugin.event_label = location.href

The following two options control the virtual page views

var id_ganalytics_plugin = id_ganalytics_plugin || {};
// Use id_ganalytics_plugin.use_vpage to enable/disable virtual page tracking
 id_ganalytics_plugin.use_vpage = false;
// Use id_ganalytics_plugin.vpage to set the virtual page to be tracked
id_ganalytics_plugin.vpage = '/service/IntenseDebate/CommentPosted';

Leave me a comment if you find this useful, or if there is anything you’d like to see chaged.

Categories: Tutorial Tags:

Hiding Google Analytics Campaign Variables

July 6th, 2009 8 comments

Do you use a service like Google Analytics for viewing your website statistics? Are you keeping track of your inbound links using campaign variables (utm_source, utm_medium, utm_campaign)? I recently ran into a situation where Google search results were linking to URLs with my campaign variables in them. Not a good thing – it really messes up your stats by reporting Google searches as coming from another source! Not to mention causing duplicate copies of your content to appear in the search listings.

Thankfully there is a quick fix for Google. Setting the canonical header link will cause Google to re-evaluate the URL next time your site is indexed. But what about a user copy-and-pasting a link to another site, or bookmarking that link?

It turns out Google Analytics can parse campaign URLs in two different ways.  It can parse them in the query parameters (those variables that come after the ‘?’ in your URLs). Or, it can also parse them when stored in the fragment after the ‘#’ in your URL. Google provides an API function to enable parsing of the fragment parameters.  The function is _setAllowHash(true).  You insert this just before the call to _trackPageview.


In theory, this should work well. Google is not supposed to index the fragment parameters that come after a URL. But what if a user bookmarks the URL?  Or what if they copy-and-paste the URL to digg or another site? This still isn’t going to solve the problem.

Time to rethink. Ideally, the campaign variables would only be available to Google Analytics and not even show in the client’s URL bar. Then they cannot be indexed by search engines and it would be unlikely they’d be copy-and-pasted to another site by the user. Here is a better solution.

When campaign variables are passed to a web page, the PHP page that is loaded can look at the $_GET parameters and detect those variables. It can then remove them, stick them in a session cookie, and redirect the user on to the correct URL – the one without the campaign variables.

The fragment portion of the URL, the part after the ‘#’, can be modified by Javascript. When the redirected page loads, before the Google Analytics code is called, a bit of Javascript code can be used to pull the campaign variables out of the cookie and place them into the fragment portion of the URL. After the Google Analytics code runs, these campaign variables can be removed, the cookie can be deleted, and the original fragment (if there was one) can be restored.

So, putting it all together, here is what happens.

  1. User clicks on a link with campaign variables and visits your website with a URL that looks something like:…
  2. The PHP code running your website detects that the user has clicked on a link with campaign variables, stores those variables in a cookie, and redirects the user to that same URL but without the campaign variables.
  3. The user’s browser visits the new page, without the campaign variables, and passes the cookie along to that page. The new URL looks something like this:
  4. The page loads in the user’s browser. As it loads a bit of Javascript runs.  The Javascript adds the campaign variables to the fragment portion of the URL.  At this snapshot in time, the URL looks like this:…
  5. Immediately after the URL is rewritten, the Google Analytics page tracker code runs and credits the source to the intended campaign. Immediately afterward, the custom Javascript erases the variables from the fragment so that the user never sees them, putting the URL back to:

That’s it. Google Analytics gets the proper information to keep track of your campaigns, the user doesn’t see a cluttered URL, and Google doesn’t get a chance to index the page with the campaign variables in the query string.

There is one bug annoyance.  That is, after the Google Analytics page tracker runs and the fragment is erased, it still leaves the single ‘#’ character in the URL.  But at least this won’t cause any harm if the user bookmarks it or copy-and-pastes it somewhere.  If anyone has ideas on how to get rid of this, please leave me feedback in the comments.

Now, if only this could be incorporated into Joost de Valk’s wonderful Google Analytics for WordPress plugin! I’ve modified my copy to do this already. See the attached Google Analytics for WordPress Modifications. This isn’t a complete plugin, only a modification to the source file for version 2.9.5 of the official plugin.
[Update: See the comments below. Adding this to Google Analytics for WordPress might not be that useful]

Lastly, the code :) Here is the bit of PHP code the detects the Google Analytics variables, sets the cookie, and redirects the user to a “clean” URL. If you have run into a similar situation and solved it a different/better way, please leave a comment and let me know what you did. I’m very interested in knowing if this could be done a better way!

// Add any Google Analytics Campaign variables to the found_tags array.
// Remove them from the _GET array so they don't get forwarded on
$found_tags = array();
foreach(array('utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content') as $tag) {
    if(isset($_GET[$tag]) && !empty($_GET[$tag])) {
        $found_tags[$tag] = $_GET[$tag];
// If any campaign variables were found, redirect the user to the "clean" URL
// after setting the 'gatmp' session cookie with the campaign variables.
if(count($found_tags) > 0) {
    setcookie('gatmp', http_build_query($found_tags));
    $dest = $_SERVER['SCRIPT_URI'];
    if( count($_GET) > 0 ) {
        $dest .= '?'.http_build_query($_GET);
    header ('HTTP/1.1 301 Moved Permanently');
    header ('Location: '.$dest);

Next, here is the javascript that detects the cookie and passes the campaign variables on to Google Analytics. This code takes the place of the normal pageTracker._trackPageview() function call.

function gaTrackerClass() {
  this.cookieVal = false;
  // Grab the cookie, if it exists, store in this.cookieVal
  if (typeof(document.cookie) != "undefined" && document.cookie.length > 0) {
    c_name = 'gatmp'; // Cookie name
    var c_start=document.cookie.indexOf(c_name + "=");
    if (c_start!=-1) {
      var v_start=c_start + c_name.length+1;
      var v_end=document.cookie.indexOf(";",v_start);
      if (v_end==-1) v_end=document.cookie.length;
      this.cookieVal = unescape(document.cookie.substring(v_start,v_end));
      // Unset the cookie so it doesn't get used multiple times
      document.cookie = c_name + "=; expires=Thu, 01-Jan-1970 00:00:10 GMT";
  // Our _trackPageview function. It emulates the behavior of the Google
  // function, using the cookie rather than query parameters in the URL.
  // If no cookie is found, just call the normal _trackPageview function
  this._trackPageview = function(str) {
    if( typeof(pageTracker) != "undefined" ) {
      if(this.cookieVal != false && typeof(window.location) != "undefined") {
        // Save the current fragment
        var hashtmp = window.location.hash;
        // Call Google Analytics and record the campaign variables
        window.location.hash = '#' + this.cookieVal;
        // Restore the fragment to its original value
        window.location.hash = hashtmp;
      } else {
var gaTracker = new gaTrackerClass();
Categories: Tutorial Tags: ,

Google Reader in Facebook

March 30th, 2009 2 comments

This has been around for a while, but I only recently started using it. Facebook’s built-in importer application can automatically add your Google Reader shared items to your mini feed.

To configure this, open your Profile to display all items you have posted.

Select your Profile at the top of the Facebook website

Select your Profile at the top of the Facebook website

On the profile page:

  1. Click “Settings” on the bottom right side of the Write Something box
  2. Choose “Google Reader” as the site to import from
  3. Enter the URL to your public “Shared items” page from Google Reader and press import

That’s all it takes. Now, when you share an article in Google Reader a post will be made in your mini feed on Facebook with a link to the article.

Steps to add Google Reader

Steps to add Google Reader