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package Net::Ping;
=head1 NAME
Net::Ping, pingecho - check a host for upness
=head1 SYNOPSIS
use Net::Ping;
print "'jimmy' is alive and kicking\n" if pingecho('jimmy', 10) ;
=head1 DESCRIPTION
This module contains routines to test for the reachability of remote hosts.
Currently the only routine implemented is pingecho().
pingecho() uses a TCP echo (I<not> an ICMP one) to determine if the
remote host is reachable. This is usually adequate to tell that a remote
host is available to rsh(1), ftp(1), or telnet(1) onto.
=head2 Parameters
=over 5
=item hostname
The remote host to check, specified either as a hostname or as an IP address.
=item timeout
The timeout in seconds. If not specified it will default to 5 seconds.
=back
=head1 WARNING
pingecho() uses alarm to implement the timeout, so don't set another alarm
while you are using it.
=cut
# Authors: karrer@bernina.ethz.ch (Andreas Karrer)
# pmarquess@bfsec.bt.co.uk (Paul Marquess)
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(ping pingecho);
use Socket;
use Carp ;
$tcp_proto = (getprotobyname('tcp'))[2];
$echo_port = (getservbyname('echo', 'tcp'))[2];
sub ping {
croak "ping not implemented yet. Use pingecho()";
}
sub pingecho {
croak "usage: pingecho host [timeout]"
unless @_ == 1 || @_ == 2 ;
local ($host, $timeout) = @_;
local (*PINGSOCK);
local ($saddr, $ip);
local ($ret) ;
# check if $host is alive by connecting to its echo port, within $timeout
# (default 5) seconds. returns 1 if OK, 0 if no answer, 0 if host not found
$timeout = 5 unless $timeout;
if ($host =~ /^\s*((\d+\.){3}\d+)\s*$/)
{ $ip = pack ('C4', split (/\./, $1)) }
else
{ $ip = (gethostbyname($host))[4] }
return 0 unless $ip; # "no such host"
$saddr = pack('S n a4 x8', AF_INET, $echo_port, $ip);
$SIG{'ALRM'} = sub { die } ;
alarm($timeout);
$ret = eval <<'EOM' ;
return 0
unless socket(PINGSOCK, PF_INET, SOCK_STREAM, $tcp_proto) ;
return 0
unless connect(PINGSOCK, $saddr) ;
return 1 ;
EOM
alarm(0);
close(PINGSOCK);
$ret == 1 ? 1 : 0 ;
}
1;
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