open TRACEROUTE, 'traceroute -xyz --whatever|'
    or die "Pipe failed: $!\n";
  {
    local $SIG{ ALRM } = sub { die "timeout" };
    eval {
      alarm ALARM_INTERVAL;
      while (<TRACEROUTE>) {
        # apply your quit test
      }
      alarm 0;
    };
    if ( $@ && $@ !~ /timeout/ ) {
      alarm 0;
      die $@;
    }
  }
  close TRACEROUTE;