I believe this section does just what you've said:

    if ($command =~ /^BYE/) {                 
         print $new_sock "OK disconnecting . . . \n";
         shutdown $new_sock, 2;
         exit 0;
     }
[download]

Thanks for mentioning security--I should have mentioned, this will be happening inside an SSL-encrypted connection (and doubtless I'll be asking about Net::SSLeay on here soon). The server rejects any connections not coming from a small range currently, but encryption is indeed necessary before I can have anything like real security.

--TQuid