Referrer Header

Having come across Facebook's Link Shim the subject of what information is transmitted when an Internet user clicks on a link on a webpage. Facebook claim that the issue is keeping their users data secure, I think that is more to do with their bottom-line.

Allowing Facebook users to post links to their own busineses does not make sense to their, or anyone's, business model. Why allow someone who is visiting your website an easy way to go somewhere else.

The implementation of the Referrer Header Meta tag requires the understanding of the syntax and options.

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Restricting the Referrer

In an attempt to control what information is available to Google Analytics, Facebook are using the Referrer Header Meta tag options.

This is what Facebook Engineering say:

" We still need to let the websites you navigate to know the traffic is from Facebook, but we also want to prevent them from reading the full source url. Otherwise, they could know where on the site you were when you clicked their link. In order to strike this balance, we've taken advantage of a new feature called the meta referrer, currently available in Chrome 17+ and Safari 6+. This allows us to specify how much of the source url to share with the external site via the Referer header. If you're using one of these supported browsers you can take advantage of this new feature. Otherwise, your browser will be routed to the slightly slower older system. "

The current version (November 2022) of Microsoft Edge is based on the Chromium technology so it is probably Chrome 17+ compliant.

Referrer Header

MDN say:

" The Referer HTTP request header contains the absolute or partial address from which a resource has been requested. The Referer header allows a server to identify referring pages that people are visiting from or where requested resources are being used. This data can be used for analytics, logging, optimized caching, and more. "

" When you click a link, the Referer contains the address of the page that includes the link. When you make resource requests to another domain, the Referer contains the address of the page that uses the requested resource. "

The referrer information the Google Analytics receives from Facebook

The Link Shim mechanism used by Facebook submits a redirect to the linked page and the referrers are modified to the following:

m.facebook.com/referrer - Mobile
l.facebook.com/referrer - Desktop
lm.facebook.com/referrer - Ether (perhaps)

In my analysis and test page for a shim of my own I will have to play around with the referer meta tag on the modal. I am not sure this can be done from the modal and I may need to construct new page that has a new header.

Syntax

There are many options that result is what is seen by the tracking software such as Google Analytics. The simplest seems to be the "stripping" of the additional characters that possibly exist in an accessing URL.

Facebook Engineering claim that the user data, such as their login information and where they are accessing from, is something that needs to be suppressed for privacy reasons. I am not so sure that this is the main reason.

The origin directive:

The Meta Tag and adding to a HTML Element:

Referrer Header

Links