clipped from: www.javascriptkit.com   

Description: A security script that checks the URL the surfer came to to arrive to the current page. If its not the specified URL, the surfer is denied access. Use this script if you wish to allow surfers to enter a page only through a predetermined previous page.

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<script> <!-- /*Referrer Checker- By JavaScript Kit (www.javascriptkit.com) Over 200+ free JavaScripts here! */ //specify valid referrals for script to accept //if you wish an entire domain to be valid, enter that (ie: "javascriptkit.com") var validreferrals=new Array() validreferrals[0]="http://www.javascriptkit.com/script/cut170.shtml" validreferrals[1]="http://javascriptkit.com/script/cut170.shtml" var passed=0 for (r=0;r<validreferrals.length;r++){ if (document.referrer.indexOf(validreferrals[r])!=-1){ passed=1 break } } if (passed==0){ alert("Access to the page denied!") history.go(-1) } //--> </script>