However, you don't want to check if the server itself is up but if a specific service is up, so a refused connection is a failure to you. If you turn on 'tcp_service_check', Net::Ping will only report success if it could actually establish a connection, and report failture if the connection was denied.

Example:

use strict;
use warnings;
use Net::Ping;

my $p = Net::Ping->new('tcp');
$p->tcp_service_check(1);

my $host = "192.168.100.12";
my $port = 80;

$p->{'port_num'} = $port;
print "The service on $host port $port is ",
        ($p->ping($host) ? "up" : "down"), ".\n";
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•Update: Note that the tcp_service_check option isn't available in the Net::Ping that is included with perl 5.8.0, however it is available in the latest version.

use IO::Socket;

$socket = eval {
   return IO::Socket::INET->new( Proto       => "tcp",
                                 PeerAddr    => $addr,
                                 PeerPort    => $port,
                                 Reuse       => 1,
                                 Timeout     => 10)
  or return undef;
};
if ($socket) {
   print "Port open\n";
   eval { return $socket->close; };
   return 1;
} else {
   print "Port NOT open\n";
   return undef;
}
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#!/usr/local/bin/perl -w
use strict;
use Net::Ping;
warn "Code is untested";
my $host="192.168.100.12";
my $p=Net::Ping->new('tcp');
$p->{'port_num'}=80;
echo "$host is alive!\n" if $p->ping($host);
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I have no idea what the syn protocol is, so I can't help you there.

CU
Robartes-

Except your snippet will say the $host is alive regardless of whether it's running a server on port 80 or not, which is what the poster wanted to know.

See my post below for the solution.

btw, syn isn't a protocol by itself but rather the first phase of the tcp-protocol. Net::Ping allows you to use it to be able to tcp-ping multiple hosts simultaneously. The docs of the latest version of Net::Ping describe it pretty well.

Granted, according to the docs, my snippet will say $host is alive if it accepts connections on port 80. This might or might not mean that a webserver is running, just that something is listening there, or - more precisely - that a successful connection was made (three way handshake completed).

robartes reads some docs...

Ah, that's what the syn 'protocol' is. The Perl 5.8.0 version of Net::Ping (whose docs I consulted) does not have this yet. If I understand correctly, for just testing one host, using syn is over the top, tcp does all of that in one call. If you are pinging various hosts, using a bunch of syn's and then using the ack method to listen for the returning ACK packets (if any) will be the way to go, as stated in the docs.

robartes reads some more docs...

Double ah. So the darn thing answers true if it gets a RST as well. xmath, you are fully correct in your reply to my comment.

Thanks for the heads up, xmath.

Update:: the confusion seems to stem from using different version of Net::Ping. My post assumes the version bundled with Perl 5.8.0, xmath is working off of version 2.28 of Net::Ping, which indeed shows the behaviour he comments on.

CU
Robartes-

The Net::Ping documentation contains an example of how to check the web port. If your code is based on that example and still doesn't work, then try including it in your question so we don't have to try and guess what is wrong with it.