#!/usr/bin/perl
use IO::Socket;
use IO::Select;
my $addr='210.245.87.255';
my $port=shift ||getservbyname('echo','udp');
my $socket=IO::Socket::INET->new(Proto=>'udp') or die $@;
$socket->sockopt(SO_BROADCAST()=>1) or die "sockopt:$!";
my $dest=sockaddr_in($port,inet_aton($addr));
my $select=IO::Select->new($socket,\*STDIN);
while(1){
       my @ready=$select->can_read;
       foreach (@ready){
         do_stdin() if $_ eq \*STDIN;
         do_socket() if $_ eq $socket;
         }
       }
     sub do_stdin{
         my $data;
         sysread(STDIN,$data,1024)||exit 0;
         send($socket,$data,0,$dest) or die "send():$!";
         }
     sub do_socket{
         my $data;
         my $addr=recv($socket,$data,.1024,0) or die"recv():$!";
         my ($port,$peer)=sockaddr_in($addr);
         my $host=inet_ntoa($peer);
         print "received",length($data),"byte from $host:$port\n";
         }