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- Short: network host monitor
- Type: comm/net
- Uploader: mlelstv@serpens.rhein.de
- Author: mlelstv@serpens.rhein.de
-
- 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
-