SERVER HTTP REFERER missing

Question

I want to use   SERVER  HTTP REFERER   in my site but i get the following   Notice  Undefined index  HTTP REFERER    I have tried printing   SERVER  This outputs the following   Array        HTTP HOST    gt  192 168 1 10      HTTP USER AGENT    gt  Mozilla 5 0  X11  Ubuntu  Linux i686  rv 15 0  Gecko 20100101 Firefox 15 0      HTTP ACCEPT    gt  text html application xhtml xml application xml q 0 9     q 0 8      HTTP ACCEPT LANGUAGE    gt  en-us en q 0 5      HTTP ACCEPT ENCODING    gt  gzip  deflate      HTTP CONNECTION    gt  keep-alive      PATH    gt   sbin  usr sbin  bin  usr bin      SERVER SIGNATURE    gt  Apache 2 2 3  CentOS  Server at 192 168 1 10 Port 80      SERVER SOFTWARE    gt  Apache 2 2 3  CentOS       SERVER NAME    gt  192 168 1 10      SERVER ADDR    gt  192 168 1 10      SERVER PORT    gt  80      REMOTE ADDR    gt  192 168 1 77      DOCUMENT ROOT    gt   var www html      SERVER ADMIN    gt  root localhost      SCRIPT FILENAME    gt   var www html sandeep test hash php      REMOTE PORT    gt  53851      GATEWAY INTERFACE    gt  CGI 1 1      SERVER PROTOCOL    gt  HTTP 1 1      REQUEST METHOD    gt  GET      QUERY STRING    gt        REQUEST URI    gt   sandeep test hash php      SCRIPT NAME    gt   sandeep test hash php      PHP SELF    gt   sandeep test hash php      REQUEST TIME    gt  1347365919     Can anyone help me to find HTTP REFERER or suggest an alternative to HTTP REFERER

User · Answer

Referer is not a compulsory header  It may or may not be there or could be modified fictitious  Rely on it at your own risk  Anyways  you should wrap your call so you do not get an undefined index error    server   isset   SERVER  HTTP REFERER        SERVER  HTTP REFERER

User · Answer

function redirectHome  theMsg   url   null   seconds   3        if   url     null             url     index php            link    Homepage         else           if  isset   SERVER  HTTP REFERER     amp  amp    SERVER  HTTP REFERER                          url     SERVER  HTTP REFERER                 link    Previous Page             else                url    index php                link    Homepage                       echo  theMsg      echo   lt div class  alert alert-info  gt You Will Be Redirected to  link After  seconds Seconds  lt  div gt        header  refresh  seconds url  url        exit

User · Answer

SOLUTION  As stated by others very well  HTTP REFERER is set by the local machine of the user  specifically the browser  which means it s not reliable for security   However  this still is entirely the way in which Google Analytics monitors where you re getting your visitors from  so  it can actually be useful to check  exclude  include  etc    If you think you should see an HTTP REFERER and do not  add this to your PHP code  preferably at the top   ini set  session referer check    TRUE      A more appropriate long-term solution  of course  is to actually update your php ini or equivalent file   This is a nice and quick way of verifying  though   TESTING  Run print   SERVER  HTTP REFERER     on your site  go to google com  inspect some text  edit it to be  lt a href  https   example com  gt LINK  lt  a gt   apply the change  then click the link   If it works  all is well and running precisely   But maybe   SERVER is wrong  or the test above says it s broken   Update your page with this  and then test again      lt script type  text javascript  gt      console log  REFER     document referrer         location referrer          lt  script gt    USES  I use HTTP REFERER to block spam sites in GoogleAnalytics   Below is a graph focusing on one particular website s referrals   From 0 to 44 in one day  it wasn t caused by real users   It was caused by a botted site trying to get my attention to buy their services   But it just started because php ini was updated to ignore the referer  which meant these spam  junk garbage sites were not getting their appropriate ERROR 403   Access Denied

User · Answer

When a web browser moves from one website to another and between pages of a website  it can optionally pass the URL it came from  This is called the HTTP REFERER  So if you don t redirect from one page to another it might be missing   If the HTTP REFERER has been set then it will be displayed  If it is not then you won t see anything  If it s not set and you have error reporting set to show notices  you ll see an error like this instead    Notice  Undefined index  HTTP REFERER in  path to filename php   To prevent this error when notices are on  I always develop with notices on   you can do this     if isset   SERVER  HTTP REFERER             echo   SERVER  HTTP REFERER           OR   echo isset   SERVER  HTTP REFERER        SERVER  HTTP REFERER           It can be useful to use the HTTP REFERER variable for logging etc purposes using the   SERVER  HTTP REFERER   superglobal variable  However it is important to know it s not always set so if you program with notices on then you ll need to allow for this in your code

User · Answer

From the documentation      The address of the page  if any  which referred the user agent to the   current page  This is set by the user agent  Not all user agents will   set this  and some provide the ability to modify HTTP REFERER as a   feature  In short  it cannot really be trusted    http   php net manual en reserved variables server php

User · Answer

You can and should never assume that   SERVER  HTTP REFERER   will be present   If you control the previous page  you can pass the URL as a parameter  site com page2 php prevUrl   urlencode  site com page1 php      If you don t control the page  then there is nothing you can do

[php] $_SERVER['HTTP_REFERER'] missing

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