pong is a utility that monitors the presence of hosts on the net
using the ICMP ECHO protocol (aka 'ping').

History:

After we got private access to the internet we had to fight many
problems with unstable software and modems or ISDN links suddenly
dropping connections.
I wrote a shell script that pinged a couple of strategic hosts and
routers. When a host answered a ping it was considered 'up', otherwise
'down' and a change in state was reported with the say command.
This way I was alerted when there was a problem even when I was busy
with other things.

This script was started every few minutes by DCron (from Matt Dillon).
This had the disadvantage that every few minutes a program used the
hard disk, trashed SnoopDos output and slowed other programs down.

pong does basically the same as the monitoring script. It takes a
list of hosts from a configuration file, tries to ping these and
report state changes on standard output. The messages are also read
from the configuration file. You can redirect the messages to SPEAK:
for audible reports or pipe the output to a shell so that any command
can be executed when a host becomes reachable or unreachable.

pong runs in infinite loop. You have to abort it with ctrl-c or
the BREAK command.

Usage:

pong CONFIG/A,CHECK/K/N,RETRY/K/N,PRESET/S,TO/K:

CONFIG/A       the name of the configuration file
CHECK/K/N  n   recheck a host every n seconds that was found alive
               the default is 300 seconds
RETRY/K/N  n   if a host does not reply in n seconds it is considered down
               the default is 30 seconds
PRESET/S       do not report the initial state of each host
TO/K           the name of a redirection file. Only status messages are
               sent to that file. A shell redirection would also send
               possible error messages.

The config file is a sequence of lines that are also parsed with ReadArgs.
The template is:

HOST/A,UP/K/A,DOWN/K/A,CHECK/K/N,RETRY/K/N

HOST/A     is the name of IP number of the host.
UP/K/A     is the string to be printed when the host becomes alive
DOWN/K/A   is the string to be printed when the host becomes unreachable
CHECK/K/N  and
RETRY/K/N  are optional CHECK and RETRY settings for this host that override
           the command line parameters

pong is written for the AS225 TCP/IP protocol stack. It should also work
with the socket.library emulation from Henning Schmiedehausen and AmiTCP.

Changes:

1.1    considers a host down if a ping fails twice in a row. This
       avoids messages if a packet is lost on transit.

Michael van Elst

 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                  130     174  74.7% -lh5- aafb Oct 11  1995 pong.cf
[generic]                 3655    5348  68.3% -lh5- 7286 Oct 11  1995 pong
[generic]                 1267    2698  47.0% -lh5- 4374 Oct 11  1995 pong.readme
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         3 files    5052    8220  61.5%            Oct 13  1995