An ICMP ping is a low-level, very small packet exchange:
xymon: Hey, server1 server1: what?? xymon: <wanders off>
On the other hand, ssh should be setting up and tearing down an encrypted connection, even though it doesn't actually login. I assume there would be multiple packets bouncing back and forth, agreeing on an encryption protocol and swapping keys, or whatever. I'm not very surprised that it takes longer than a ping to complete the connection.
Ralph Mitchell
On Mon, Aug 24, 2015 at 11:04 PM, Jeremy Laidman <jlaidman at rebel-it.com.au> wrote:
I've noticed the same thing on many of my servers. Without really thinking about it, I just assumed that the xymonnet TCP connection measurements were taking into account (removing) network latency time, and only giving the latency within the server being tested. Thinking about it now, I'm not sure how xymonnet would do this.
Yes, I believe xymonping uses ICMP. You can run xymonping directly like:
sudo -u xymon /usr/lib/xymon/server/bin/xymonping 10.100.2.17
and see how it compares with the graph, or "ping" or "time telnet 10.100.2.17 22 </dev/null".
J
On 25 August 2015 at 08:02, Shawn Heisey <hobbit at elyograg.org> wrote:
Here is a "connection times" graph from Xymon:
https://www.dropbox.com/s/voyqnzfnsqaact9/xymonresponsegraph.png?dl=0
This shows "conn" times in the 40 millisecond rang, and "ssh" times in the 200 microsecond range.
What is the source of the "conn" graph? I would have guessed ICMP, but it doesn't make any sense for a ping to take longer than an ssh connection, especially not that much longer. This is what I get if I ping that machine from the xymon server ... it doesn't take anywhere even CLOSE to 40 milliseconds:
[root at mcp xymon]# ping palazzo PING palazzo.REDACTED.com (10.100.2.17) 56(84) bytes of data. 64 bytes from palazzo.REDACTED.com (10.100.2.17): icmp_seq=1 ttl=62 time=0.572 ms 64 bytes from palazzo.REDACTED.com (10.100.2.17): icmp_seq=2 ttl=62 time=0.582 ms 64 bytes from palazzo.REDACTED.com (10.100.2.17): icmp_seq=3 ttl=62 time=0.573 ms 64 bytes from palazzo.REDACTED.com (10.100.2.17): icmp_seq=4 ttl=62 time=0.611 ms 64 bytes from palazzo.REDACTED.com (10.100.2.17): icmp_seq=5 ttl=62 time=0.890 ms ^C --- palazzo.REDACTED.com ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4003ms rtt min/avg/max/mdev = 0.572/0.645/0.890/0.126 ms
Can anyone shed light on this? My server config includes the following line:
FPING="xymonping"
My xymon server is version 4.3.14.
Thanks, Shawn
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