a couple of weeks ago, and have since implemented a few of my proposals, and found a few new ideas for improvements.
You can check out my changes
My problem is as follows: the maintainer of the Net::Ping module, Russell Mosemann, has not responded to my e-mail for the past 2 weeks. I'm assuming, since I can find no recent reference of him in comp.lang.perl.*, and since the module has not been changed since 1996, that he has basically disappeared off the face of the Perl world.
I'm currently in the process on writing an Request For Comments and possibly an application for maintainership of the module to the comp.lang.perl.modules newsgroup.
Before submitting the RFC to c.l.p.m., I thought I'd include it here on PM and take comments from the monks here. So, here goes:
The following is a request for comments on a list of proposed changes
to the Net::Ping module. After doing some basic searching of the web,
and taking a look at the actual source code, I've come up with a list
of problems and changes that I am interested in implementing. I would
appreciate any comments or suggestions you may have on this
matter. References to web sites where I have found descriptions of
some problems are given within square brackets; see the footnotes at
the bottom of this message for the links. A quick search on
http://groups.google.com for "Net::Ping Problems" on comp.lang.perl.*
will turn up a host of problems that could be resolved if the changes
listed below were made. Without further ado, here goes:
- Summary -
Already implemented changes:
1. Removal of alarm() function
2. TCP ping now functional on MSWin32 systems
3. Incorrect returns of "false" removed from TCP ping
4. Removal of unneeded warning in the module's POD
To be (possibly) implemented:
5. Creation of a new "external" protocol
6. Creation of a new "auto" protocol
7. Documentation update
8. Change in the default ping protocol
9. Allowing for user-specified port in TCP ping
10. UDP ping fixes?
- Detail -
This first group of details pertains to changes I have already
implemented to Net::Ping. A second group, below, discusses potential
changes that I've not implemented yet.
1. The alarm() function is currently used to implement timeouts on a
TCP ping. This makes Net::Ping unusable in systems which do not
implement alarm() (i.e. MSWin32),  and may also cause problems w
scripts that use alarm() or sleep(). I've re-written the TCP ping
code to use a non-blocking connect() and select() to implement the
2. On the other hand, the use of non-blocking connect() is not
supported on MSWin32 either. So, I've added special code to handle
TCP pings on Windows platforms. It uses Win32::Process::Create (if
it exists on the system) to spawn a child process, which attempts t
do a (blocking) TCP connect to the appropriate host. If the new
process does not return before the timeout has passed, it is killed
off, and false is returned.
3. The TCP pinging function, ping_tcp(), currently returns false
negatives when the remote host responds with "Connection refused"
(which will happen for any live machine that's not listening on the
TCP echo port).  In this case, the call to connect() in the
current Net::Ping fails, so Net::Ping returns false. However, if
the error given is connection refused, this implies that there is
indeed a host at the other end of the pipe, which sent the
"connection refused" message. Hence, ping_tcp() should return true
in this case. The changes described above in item #1 have the
side-effect of removing this false negative on systems that support
non-blocking connect(); specific logic written into the Win32 TCP
ping handles this case for MS platforms.
4. I've also removed the POD that warns about the use
of alarm() in conjunction with Net::Ping, since the warning is no
longer necessary. 
The following are potential additional changes. Comments on these
would definitely be appreciated. They are ordered in roughly the order
in which I would want to implement them. (In other words, easy and/or
more useful things are listed first).
5. It is well-known that the most accurate method of pinging is an
ICMP ping.  Unfortunately, ICMP ping from native perl requires
privileged (AKA "root") access on all systems but VMS. To remedy
this, I've written a module, Net::Ping::External , which interfa
with the native system's "ping" command for a variety of operating
systems. The "ping" system utility always (AFAIK) uses an ICMP
ping, so the results of Net::Ping::External are probably more
reliable than Net::Ping's TCP and UDP pinging modes. Hence, I
propose that a new protocol be made available to Net::Ping, called
"external", which uses Net::Ping::External to do a ping. This will
allow for the accuracy of an ICMP ping without the user needing
privileges to run the script as root or administrator. If the user
does not have Net::Ping::External installed, Net::Ping will simply
croak() about the "external" protocol being currently available on
their system, much like it already does if a non-root user attempts
an ICMP ping.
6. I propose another protocol be added, called "auto", which is meant
for "newbie" use. "auto" would automatically determine the most
accurate pinging method available on the current system in the
* If the script is running under root privileges, the "icmp"
protocol is used.
* Otherwise, we check to see if Net::Ping::External is available;
if so, the "external" protocol is used.
* If neither of these is available, TCP ping is used.
* If there is some sort of error with TCP ping, we finally fall
back to UDP ping.
The "auto" protocol has the main advantage of providing accurate
results to people who don't care to learn about the various pinging
methods and choosing the best one. A new Net::Ping object that is
constructed with a protocol of "auto" would find out the
appropriate protocol on the first call to the ping() method, and
use that method for puture calls; hence, these checks would not
need to be made for every single ping.
7. The documentation needs updating. The current Net::Ping
documentation gives no explanation of why certain pinging strategie
are better than others, or any explanation of why the module is
prone to giving "incorrect" results.
8. The default pinging method is to use UDP. Since UDP seems to be the
most inaccurate way of getting results, I'm not at all sure why thi
was made the default in the first place. On the other hand, I'm not
sure that I want to mess with the default that's been in place for
years; there could be scripts out there that depend on it. If I
were to change the default, I'd probably change it to the "auto"
method, since the purpose of this method is to always return the
most accurate results.
9. The TCP protocol could possibly be improved by allowing the user to
specify a specific port to connect() to. If it is known that the
remote host is, for example, a web server, we are more likely (due
to remote firewall rules) to get an accurate result by trying a
connect() to port 80 than a connect() to port 7.
10. I've not even looked at UDP ping's code yet, but there are
obviously fixes that need to be made. One known issue is that UDP
pings appear to not play nicely with the Socket.pm module on Linux
Please let me know what thoughts you have on this proposal. I've tried
contact Net::Ping's maintainer, Russell Mosemann, for a couple weeks
now, but have gotten no response. Since the module has not been
updated since 1996, and Russell has not (to my knowledge) posted to
comp.lang.perl.* since that time, I'm assuming he's gone incognito. I
would like to know who I need to contact, in lieu of Russell Mosemann,
to submit patches to. If there is no currently-interested maintainer
of Net::Ping, I think I would like to apply for maintainership of this
module; who would I contact to discuss this?
- Colin McMillen (CPAN ID: COLINM)