Subject: [ANNOUNCE] Net::Ping 2.02 released
From: [email-masked] (Russell Mosemann)
Date: 27 Sep 1996 03:01:46 GMT
Newsgroups: comp.lang.perl.announce,comp.lang.perl.misc

Version 2.02 of Net::Ping has been uploaded to the CPAN archives
and should be available shortly.  This new version has been rewritten
to be object oriented and includes the original tcp ping, a udp ping
and a "real" icmp ping.  The man page follows.

NAME
     Net::Ping - check a remote host for reachability

SYNOPSIS
     use Net::Ping;

     $p = Net::Ping->new();
     print "$host is alive.\n" if $p->ping($host);
     $p->close();

     $p = Net::Ping->new("icmp");
     foreach $host (@host_array)
     {
         print "$host is ";
         print "NOT " unless $p->ping($host, 2);
         print "reachable.\n";
         sleep(1);
     }
     $p->close();

     $p = Net::Ping->new("tcp", 2);
     while ($stop_time > time())
     {
         print "$host not reachable ", scalar(localtime()), "\n"
             unless $p->ping($host);
         sleep(300);
     }
     undef($p);

     # For backward compatibility
     print "$host is alive.\n" if pingecho($host);

DESCRIPTION
     This module contains methods to test the reachability of
     remote hosts on a network.  A ping object is first created
     with optional parameters, a variable number of hosts may be
     pinged multiple times and then the connection is closed.

     You may choose one of three different protocols to use for
     the ping.  With the "tcp" protocol the ping() method
     attempts to establish a connection to the remote host's echo
     port.  If the connection is successfully established, the
     remote host is considered reachable.  No data is actually
     echoed.  This protocol does not require any special
     privileges but has higher overhead than the other two
     protocols.

     Specifying the "udp" protocol causes the ping() method to
     send a udp packet to the remote host's echo port.  If the
     echoed packet is received from the remote host and the
     received packet contains the same data as the packet that
     was sent, the remote host is considered reachable.  This
     protocol does not require any special privileges.

     If the "icmp" protocol is specified, the ping() method sends
     an icmp echo message to the remote host, which is what the
     UNIX ping program does.  If the echoed message is received
     from the remote host and the echoed information is correct,
     the remote host is considered reachable.  Specifying the
     "icmp" protocol requires that the program be run as root or
     that the program be setuid to root.

     Functions

     Net::Ping->new([$proto [, $def_timeout [, $bytes]]]);
     Create a new ping object.  All of the parameters are
     optional.  $proto specifies the protocol to use when
     doing a ping.  The current choices are "tcp", "udp" or
     "icmp".  The default is "udp".

     If a default timeout ($def_timeout) in seconds is
     provided, it is used when a timeout is not given to the
     ping() method (below).  The timeout must be greater than
     0 and the default, if not specified, is 5 seconds.

     If the number of data bytes ($bytes) is given, that many
     data bytes are included in the ping packet sent to the
     remote host. The number of data bytes is ignored if the
     protocol is "tcp".  The minimum (and default) number of
     data bytes is 1 if the protocol is "udp" and 0
     otherwise.  The maximum number of data bytes that can be
     specified is 1024.

     $p->ping($host [, $timeout]);
     Ping the remote host and wait for a response.  $host can
     be either the hostname or the IP number of the remote
     host.  The optional timeout must be greater than 0
     seconds and defaults to whatever was specified when the
     ping object was created.  If the hostname cannot be
     found or there is a problem with the IP number, undef is
     returned.  Otherwise, 1 is returned if the host is
     reachable and 0 if it is not.  For all practical
     purposes, undef and 0 and can be treated as the same
     case.

     $p->close();
     Close the network connection for this ping object.  The
     network connection is also closed by "undef $p".  The
     network connection is automatically closed if the ping
     object goes out of scope (e.g. $p is local to a
     subroutine and you leave the subroutine).

     pingecho($host [, $timeout]);
     To provide backward compatibility with the previous
     version of Net::Ping, a pingecho() subroutine is
     available with the same functionality as before.
     pingecho() uses the tcp protocol.  The return values and
     parameters are the same as described for the ping()
     method.  This subroutine is obsolete and may be removed
     in a future version of Net::Ping.

WARNING
     pingecho() or a ping object with the tcp protocol use
     alarm() to implement the timeout.  So, don't use alarm() in
     your program while you are using pingecho() or a ping object
     with the tcp protocol.  The udp and icmp protocols do not
     use alarm() to implement the timeout.

NOTES
     There will be less network overhead (and some efficiency in
     your program) if you specify either the udp or the icmp
     protocol.  The tcp protocol will generate 2.5 times or more
     traffic for each ping than either udp or icmp.  If many
     hosts are pinged frequently, you may wish to implement a
     small wait (e.g. 25ms or more) between each ping to avoid
     flooding your network with packets.

     The icmp protocol requires that the program be run as root
     or that it be setuid to root.  The tcp and udp protocols do
     not require special privileges, but not all network devices
     implement the echo protocol for tcp or udp.

     Local hosts should normally respond to pings within
     milliseconds.  However, on a very congested network it may
     take up to 3 seconds or longer to receive an echo packet
     from the remote host.  If the timeout is set too low under
     these conditions, it will appear that the remote host is not
     reachable (which is almost the truth).

     Reachability doesn't necessarily mean that the remote host
     is actually functioning beyond its ability to echo packets.

     Because of a lack of anything better, this module uses its
     own routines to pack and unpack ICMP packets.  It would be
     better for a separate module to be written which understands
     all of the different kinds of ICMP packets.

-- 
Russell Mosemann     Concordia College      Voice: (402) 643-7445
Computing Center     Seward, NE 68434       Fax:   (402) 643-4073
"Look before you leap."  "He who hesitates is lost."