RSS
readers misusing the referer field?

Very few of these are true referers. No one clicked on a
link on the NewsGator page to get to my site, yet I have almost
2000 referers from that page in my logs for this month. Checking my
logs more closely, it appears that each time an RSS file from my
site is loaded by one of these applications, a referer is deposited
in the log file. Each time I load a page in Internet Explorer, I
don’t leave a referer for www.microsoft.com/ie in the log files of
the site whose page I loaded, so why should any of the RSS readers
be different?

The definition of referer from RFC 2616 on HTTP 1.1 seems
relevant to the question. It states that “The Referer[sic]
request-header field allows the client to specify, for the server’s
benefit, the address (URI) of the resource from which the
Request-URI was obtained” and that “the Referer field MUST NOT be
sent if the Request-URI was obtained from a source that does not
have its own URI”.

This is an interesting point – some aggregators have
at various times allowed people to include their own URL’s as part
of the referrer and this encourages back-linking by allowing
writers to find out about their readers. I’m not sure what value a
plain static URL has, though, considering the fact that the User
Agent also identifies the software.