What is your port_not_listening()? here's mine:

sub port_not_listening
{
# UNTESTED
my $timeout = 10;
my ($remote, $port) = split(/:/, $_[0]);
    
    $iaddr   = inet_aton($remote) or return 1;
    $paddr   = sockaddr_in($port, $iaddr);

    $proto   = getprotobyname('tcp');  # X uses tcp, right?
    socket(SOCK, PF_INET, SOCK_STREAM, $proto)  or die "socket: $!";

    eval
    {
        local $SIG{ALRM} = sub { die "connection timeout\n" }; 
        alarm $timeout;
        connect(SOCK, $paddr) or die "$! for $remote\n";
        alarm 0;
    };

    return 1 if ( $@ );
    return 0;
}
[download]

Update: Halley points out correctly (below) that the line my ($remote, $port) = split(/:/, $_[0]); is unlikely to actually yield a correct port number.

--Bob Niederman, http://bob-n.com