threadn {
    eval {
        sighandler = {};
        alarm 15;        ## alarm#1
        start threadn+1;
        start threadn+2;
        threadn+2->join
        threadn+1->join
    }
    alarm 0;
}
threadn+1{
    eval{
        sighandler = {};
        alarm 15;          ## alarm#2
        @input = qx[ ping ];
    }
    alarm 0;
}
threadn+2 {
    @input = qx[ tcpdump;
    return @input;
}

##</code><code>##

sub ping {
    my $dns_name = shift;
    open my $cmd, "ping -c 15 -i 1 $dns_name" or die;
    m/PING (.*).et.byu.edu/ and return $1 while <$cmd>;
    return;
}