Ping from cron not having same effect as ping from console

I'm running a RedHat Enterprise 2.1 server as a group development
platform. We're having some network problems which are being worked
on, but right now I need a workaround. The problem is that this
server drops off of the network a couple of times a day. I've found
that if I just ping another server from that server it comes back on
the network, everybody can see it and everything is fine.

To keep the server on the network I set up a cron job to ping another
server every two minutes. I can see this ping running every two
minutes with "ps -e | grep ping". However, the machine still drops
off of the network. When the server drops off of the network I wait
until I see the cron ping as above and then verify that it is still
off of the network. So the cron ping doesn't get the machine back on
the network. Then I do a ping from a console and the server comes
back on the network.

For some reason the cron ping doesn't have the same effect that a ping
from the console does. The crontab ping entry is by the same user
that I am logged in as when I do the ping from the console.

Anyone have any suggestions? Why does a ping from the console have a
different effect than a ping from cron.

Hi Dean -

On 24 Feb 2004 08:18:17 -0800, (E-Mail Removed) (Dean Schulze)
wrote:

>For some reason the cron ping doesn't have the same effect that a ping
>from the console does. The crontab ping entry is by the same user
>that I am logged in as when I do the ping from the console.
>
>Anyone have any suggestions? Why does a ping from the console have a
>different effect than a ping from cron.

I just set up my first cron stuff last night and found that a command
that worked from the console and wasn't working from cron was because
the command couldn't be found.

I had to add PATH=[path directories] to the crontab file. Apparently
without that the path is empty. As an alternative, you could put in
the full path with the ping command, e.g. /bin/ping [ping parameters]
(or whatever directory is correct for ping on your system).

This may not be your problem, but it's something to check.

--
Ken
http://www.ke9nr.net/

"Dean Schulze" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> I'm running a RedHat Enterprise 2.1 server as a group development
> platform. We're having some network problems which are being worked
> on, but right now I need a workaround. The problem is that this
> server drops off of the network a couple of times a day. I've found
> that if I just ping another server from that server it comes back on
> the network, everybody can see it and everything is fine.
>
> To keep the server on the network I set up a cron job to ping another
> server every two minutes. I can see this ping running every two
> minutes with "ps -e | grep ping". However, the machine still drops
> off of the network. When the server drops off of the network I wait
> until I see the cron ping as above and then verify that it is still
> off of the network. So the cron ping doesn't get the machine back on
> the network. Then I do a ping from a console and the server comes
> back on the network.
>
> For some reason the cron ping doesn't have the same effect that a ping
> from the console does. The crontab ping entry is by the same user
> that I am logged in as when I do the ping from the console.
>
> Anyone have any suggestions? Why does a ping from the console have a
> different effect than a ping from cron.


I prefer fping (http://www.fping.com) for scheduled / scripted stuff.

However, to me what you're saying sounds more like a network switch / mac
address / arp issue. Try changing the port on the switch to which the
server is connected.

Brendon
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