use IO::Socket::INET;
 
my $port = '7777';
if ( defined $ARGV[0] ) { $port = $ARGV[0] }
# auto-flush on socket
$| = 1;

$SIG{ 'TERM' } = $SIG{ 'INT' } = sub { $socket->close(); };
$SIG{ 'PIPE' } = 'IGNORE';
my $client_socket;

# creating a listening socket
my $socket = new IO::Socket::INET (
    LocalHost => '0.0.0.0',
    LocalPort => $port,
    Proto => 'tcp',
    Listen => 5,
    Reuse => 1
);
die "cannot create socket $!\n" unless $socket;
print "server waiting for client connection on port $port\n";

# waiting for a new client connection
$client_socket = $socket->accept();
 
while(1)
{

    # get information about a newly connected client
    my $client_address = $client_socket->peerhost();
    my $client_port = $client_socket->peerport();
    print "connection from $client_address:$client_port\n";

    # read up to 1024 characters from the connected client
    my $data = "";
    $client_socket->recv($data, 1024);
    print "received data: $data\n";
 
    # write response data to the connected client
    $data = "ok";
    $client_socket->send($data);
 
    # notify client that response has been sent
    #shutdown($client_socket, 1);
}