"Ping" doesn't work properly

I only want to send one packet to another host to check whether it is
connected or not. I want to have 2 seconds timeout.

I use, ping -c 1 -w 2 192.168.0.2

If host is not connected, it fails correctly. BUT summary says.

PING 192.168.0.2 from 192.168.0.1 : 56(84) bytes of data

--------192.168.0.2 ping statastics --------
2 packets transmitted, 0 received, 100% loss, time 999ms

Why 2 packets are sent instead of 1 (specified) and why it only waits
for 999 ms instead of 2 seconds.

Even if I use: ping -c 5 -w 2 192.168.0.2, it has the same result. Here
I wanted to send 5 packets but, again 2 packets were sent?

What is wrong here? Please help me.
Thanks a lot



Neel

Neel <(E-Mail Removed)> wrote:
> I only want to send one packet to another host to check whether it is
> connected or not. I want to have 2 seconds timeout.

> I use, ping -c 1 -w 2 192.168.0.2

> If host is not connected, it fails correctly. BUT summary says.

> PING 192.168.0.2 from 192.168.0.1 : 56(84) bytes of data

> --------192.168.0.2 ping statastics --------
> 2 packets transmitted, 0 received, 100% loss, time 999ms

> Why 2 packets are sent instead of 1 (specified) and why it only waits
> for 999 ms instead of 2 seconds.

The two vs one may simply be an OBO bug (off by one) - send one right
away, send one after the first timeout. (Double check that the manpage
for your ping's -c option matches your expectation of course The
999ms could be that the ping command got some other indication that
the response wasn't going to arrive - sometimes I've seen messages
elsewhere that imply that ARP sent something up the stack that said it
couldn't map the IP to a MAC - perhaps that makes it all the way to
ping which then "knows" that waiting for the full timeout is
pointless.

Might be worthwhile doing a system call trace of the ping command.

> Even if I use: ping -c 5 -w 2 192.168.0.2, it has the same result. Here
> I wanted to send 5 packets but, again 2 packets were sent?

Might check the ARP tables and the ARP timeouts. If the system is not
up, and is "local" then the gating factor might be ARP not ping.

rick jones
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