use IO::Socket;
use IO::Select;

my $port1 = 80;
my $port2 = 81;

my $sock1 = new IO::Socket::INET(Port => $port1,
                                 Proto => 'tcp',
                                 Listen => 1,
                                 Reuse => 1,
                                 Timeout => 60);
die "can't open $port1 ($!)" unless $sock1;

my $sock2 = new IO::Socket::INET(Port => $port2,
                                 Proto => 'tcp',
                                 Listen => 1,
                                 Reuse => 1,
                                 Timeout => 60);
die "can't open $port2 ($!)" unless $sock1;

my $sel = new IO::Select;
$sel->add($sock1);
$sel->add($sock2);

while(1)
{
   my @handles = $sel->can_read(10); # timeout after 10 secs
   foreach my $h (@handles)
   {
      if($h == $sock1)
      {
         # do something with port 80 data
      }
      elsif($h == $sock2)
      {
         # do something with port 81 data
      }
   }
}