for($i=0;$i<3;$i++){

    if($i == 0){ $port=80; }
    if($i == 1){ $port=443; }
    if($i == 2){ $port=53; }
    ...
}
[download]

On a side note, as $i isn't being used in the rest of the loop, this could be shorter written as

for my $port (80, 443, 53) {
    ...
}
[download]