In what cases will HTTP REFERER be empty

Question

I know it s possible to get an empty HTTP REFERER  Under what circumstances does this happen  If I get an empty one  does it always mean that the user changed it  Is getting an empty one the same as getting a null one  and under what circumstances do I get that too

User · Answer

I have found the browser referer implementation to be really inconsistent.

For example, an anchor element with the "download" attribute works as expected in Safari and sends the referer, but in Chrome the referer will be empty or "-" in the web server logs.

<a href="http://foo.com/foo" download="bar">click to download</a>

Is broken in Chrome - no referer sent.

User · Answer

BalusC s list is solid  One additional way this field frequently appears empty is when the user is behind a proxy server  This is similar to being behind a firewall but is slightly different so I wanted to mention it for the sake of completeness

User · Answer

It will may be empty when the enduser   entered the site URL in browser address bar itself  visited the site by a browser-maintained bookmark  visited the site as first page in the window tab  clicked a link in an external application  switched from a https URL to a http URL  switched from a https URL to a different https URL  has security software installed  antivirus firewall etc  which strips the referrer from all requests  is behind a proxy which strips the referrer from all requests  visited the site programmatically  like  curl  without setting the referrer header  searchbots

User · Answer

HTTP REFERER - sent by the browser  stating the last page the browser viewed   If you trusting  HTTP REFERER  for any reason that is important  you should not  since it can be faked easily    Some browsers limit access to not allow HTTP REFERER to be passed Type a address in the address bar will not pass the HTTP REFERER open a new browser window will not pass the HTTP REFERER  because HTTP REFERER   NULL has some browser addon that blocks it for privacy reasons  Some firewalls and AVs do to    Try this firefox extension  you ll be able to set any headers you want    Master of Celebration   Firefox    extensions  refspoof  refontrol  modify headers  no-referer  Completely disable  the option is available in about config under  network http sendRefererHeader  and you want to set this to 0 to disable referer passing   Google chrome   Chromium   extensions  noref  spoofy  external noreferrer  Completely disable  Chnage    config google-chrome Default Preferences or    config chromium Default Preferences  and set this                enable referrers   false             Or simply add --no-referrers to shortcut or in cli   google-chrome --no-referrers   Opera   Completely disable  Settings   Preferences   Advanced   Network  and uncheck  Send referrer information   Spoofing web service   http   referer us   Standalone filtering proxy  spoof any header    Privoxy  Spoofing http referer  when using wget     --referer url     Spoofing http referer when using curl  -e  --referer   Spoofing http referer wth telnet  telnet www yoursite com 80  press return  GET  index html HTTP 1 0  press return  Referer  http   www hah-hah com  press return   press return again

User · Answer

It will also be empty if the new Referrer Policy standard draft is used to prevent that the referer header is sent to the request origin  Example    lt meta name  referrer  content  none  gt    Although Chrome and Firefox have already implemented a draft version of the Referrer Policy  you should be careful with it because for example Chrome expects no-referrer instead of none  and I have seen also never somewhere

[security] In what cases will HTTP_REFERER be empty

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