You can use these environment variables, which are in %ENV: These are the main ones to use, although the last is not as reliable as the first two and can be easily faked. However, a simple check should keep out 99.9% of the people: 
unless ($ENV{'HTTP_REFERER'} eq "$mypage") {
  print "Access forbidden. Goodbye.\n";
  exit;
}

[download]
P.S. Yes, 'referer' is spelled wrong, but that's now the official way. :)

In reply to Re: Checking where my CGI is bing called from. by turnstep
in thread Checking where my CGI is bing called from. by Speedfreak

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