Dear Monks,

Please enlighten me about Net::Ping.

Here's my script:
#!/usr/bin/perl -w
use strict;
use Net::Ping;
use Getopt::Std;

my $protocal     = "icmp";
my $network     = "user must enter";
my $start    = 0;
my $end        = 255;
my $timeOut     = 1;

use vars qw/ $opt_p $opt_N $opt_S $opt_E $opt_T $opt_h/;
getopt( "p:N:S:E:T:h" );
if( $opt_p ) {$protocal = $opt_p;}
if( $opt_N ) {$network    = $opt_N} else { &usage(); exit(); }
if( $opt_S ) {$start    = $opt_S}
if( $opt_E ) {$end    = $opt_E}
if( $opt_T ) {$timeOut    = $opt_T}
if( $opt_h ) {&useage(); exit();}

my $p = Net::Ping->new($protocal,$timeOut);

for(my $node=$start; $node<$end; $node++){
    my $address = "$network.$node";
    print $address,($p->ping($address) ? ' is alive' : ' is not alive'
+),"\n";
}

$p->close();

sub usage {
print<<DOIT;
    $0 -N<network> [-p<protocal>][-S<start>][-E<end>][-T<timeout>][-h]
    network actually first 3 octects of an IP address
    protocal can be icmp, tcp or udp default is icmp
    start    default 0 
    end    default 255 
    timeout    default 1 
DOIT
}

[download]

I have been executing it on a NT system from a cygwin bash
shell (if that makes a difference)

Here's the output from various runs of the script:
$ ./ping.pl -N 123.321.12 -ptcp
123.321.12.0 is not alive
123.321.12.1 is not alive
^C
// script seemed to hang 

$ ./ping.pl -N 123.321.12 -pudp
123.321.12.0 is not alive
123.321.12.1 is not alive
123.321.12.2 is not alive
123.321.12.3 is not alive
123.321.12.4 is not alive
123.321.12.5 is not alive
123.321.12.6 is not alive
123.321.12.7 is not alive
... 
123.321.12.254 is not alive

$ ./ping.pl -N 123.321.12   
icmp ping requires root privilege at ./ping.pl line 21

[download]

My questions:

1) Why did ping.pl -N 123.321.12 -ptcp hang?
2) Why didn't ping.pl -N 123.321.12 -pudp not ping anything?
3) Why did ping.pl -N 123.321.12 get that error message?

I don't know much ... about networks :)

In reply to Why does Net::Ping behave this way? by rbc

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