Originally Posted by Sin_Vraal

http://perldoc.perl.org/functions/pack.html
its a clever way of writing a string, then evaluating it.

Although you can read up on pack, it will probably bore u, so just change eval to print and see what it says.

my$d='bupbup.com';if($ENV{'HTTP_HOST'}&&index($ENV {'HTTP_HOST'},$d)==-1){print "Content-type: text/html\n\n";print "This software is licensed for use on $d only";exit;}$HEADER=0;

essentially, this is security software.