in reply to is there script to detect if remote machine is alive/reachable w/o using Net::Ping?

odd you should say that. I use almost exactly the same code and I have never been troubled with lengthy delays. Are you sure you don't have a problem with DNS name resolution (even though your example shows the use of numeric IP addresses)?

Here is the code I use. It is part of a CGI script, so there is a $q CGI object hanging around, and a few constant values for pretty colors, such as use constant PAINT_OK => '#008000' and so on.

sub test_socket {
    my $s = IO::Socket::INET->new( @_, Timeout=>2, Proto => 'tcp' );
    if( $s ) {
        close $s;
        $q->font( {-color=>PAINT_OK},  'ok' );
    }
    else {
        $q->font( {-color=>PAINT_NOK}, $! )
    }
}

my %tcp_probe = (
    'foo<br>Apache'   => test_socket( PeerHost => '172.17.0.2',     Pe
+erPort => 80,   ),
    'foo<br>Lotus'    => test_socket( PeerHost => '172.17.0.2',     Pe
+erPort => 1352, ),
    'bar<br>Apache'   => test_socket( PeerHost => '172.17.0.3',     Pe
+erPort => 80,   ),
    'bar<br>Lotus'    => test_socket( PeerHost => '172.17.0.3',     Pe
+erPort => 1352, ),
    'example<br>Apache' => test_socket( PeerHost => 'www.example.com',
+ PeerPort => 80,   ),
    'example<br>Domino' => test_socket( PeerHost => 'www.example.com',
+ PeerPort => 8000, ),
    'example<br>Lotus'  => test_socket( PeerHost => 'www.example.com',
+ PeerPort => 1352, ),
    'Web<br>Proxy'       => test_socket( PeerHost => '172.17.0.9',    
+ PeerPort => 8080, ),
    'baz<br>Sybase' => test_socket( PeerHost => '172.17.0.1',     Peer
+Port => 4100, ),
    'baz<br>Samba'  => test_socket( PeerHost => '172.17.0.1',     Peer
+Port => 139,  ),
);

print $q->h3('Mission Critical'), $q->table(
    $q->TR(
        $q->th( {-width=>60, -valign=>'bottom', -bgcolor=>'#fff0e0'},
            [ sort keys %tcp_probe ]
        )
    )
    . $q->TR(
        $q->td( {-width=>60, -align=>'center'},
            [ map { $tcp_probe{$_} } sort keys %tcp_probe ]
        )
    )
);

[download]

The only other thing I could suggest would be to set an alarm of a second or two, an alarm handler and eval the code, in order to forcibly cancel the code. But if it's blocking at a low enough level, alarm won't necessarily work either, I've had that happen in the past.


print@_{sort keys %_},$/if%_=split//,'= & *a?b:e\f/h^h!j+n,o@o;r$s-t%t#u'
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Re: Re: is there script to detect if remote machine is alive/reachable w/o using Net::Ping?
by Anonymous Monk on Jun 07, 2002 at 20:31 UTC
    tnx guys, ive tried what GRINDER recommended and heres what happened to my code: 
    use IO::Socket;

sub doit
{
$ip1="210.22.106.31";
$host="$ip1";
$port="23";
$fnd="";

$pong=`ping -c 3 $host`;
$fnd=($pong=~m/(..)%/gi);
$xcd=$1;  

 if ($xcd!=00)
 {    

 $SIG{ALRM} = \&timed_out;
 eval { 
 alarm (3); 
 $remote = IO::Socket::INET -> new (
             Proto => "tcp",
             PeerAddr => $host,
             PeerPort => $port,
         Timeout => 2
             ) or die "." ;
 alarm (0); 
 };
 sub timed_out {
 die ".";
 }

 $| = 1;

if ($remote) 
{
close $remote;
print "Socket ready...\n";
}
else
{
print "Try again...\n";
}
}
else
{
print "Pinged timed out!\n";
}

    [download]
    This doenst seem to work? It also hangs just as before? sigh... got any substitute for EVAL which works for Sockets? Thank you all for helping me. I really dont know what to do next? Lovelots and *mwah* *mwah* *mwah*, Cherry.
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