[Xymon] Debian 9 stretch clients - trends netstat graph bug?
John Horne
john.horne at plymouth.ac.uk
Mon Mar 18 19:11:59 CET 2019
On Mon, 2019-03-18 at 10:30 -0700, Japheth Cleaver wrote:
> This is not just a Debian thing -- it looks like it results from output
> changes in recent versions of netstat/net-tools (recent Fedora is affected
> too).
>
> I think the easiest fix will be to move to PCRE parsing to catch the
> differing versions, which is how we're handling the BSDs and some of the
> esoteric unicies. (Although there's a legacy RHEL3 Linux OS type from back in
> the day, this is one of the things we'll want to catch centrally moving
> forward.)
>
I was going to take a look at the problem tomorrow. From my very quick look at
the code I thought it already had support for PCRE, and so hopefully it would
just require changing the code from a fixed string to a regex to cater for the
current and new net-tools versions.
John.
>
> On 3/13/2019 7:53 AM, SebA wrote:
> > Hi John,
> >
> > I can confirm that we have the same issue on Debian 9 clients on the
> > Network I/O (as labelled) graph.
> >
> > Kind regards,
> >
> > SebA
> >
> >
> >
> > On Tue, 12 Mar 2019 at 22:48, John Horne <john.horne at plymouth.ac.uk> wrote:
> > > Hi,
> > >
> > > We have three Debian 9 (stretch) servers running the xymon-client package
> > > (version 4.3.28-2). I noticed yesterday that the 'trends' column for
> > > these
> > > clients was showing a 'TCP/IP statistics' graph, but was only showing
> > > values
> > > for the 'In' graph. Both the 'Out' and 'Retrans' values were NaN.
> > >
> > > If anyone else is running the Xymon client on a Debian 9 server, or may
> > > be even
> > > Debian 8, could they check their 'trends' graphs and see if the same
> > > problem
> > > exists for them. Thanks.
> > >
> > > As far as I can tell this started when we upgraded the client server O/S
> > > from
> > > Debian 7 to 9 (a few months ago now!). It seems there were values for all
> > > 3
> > > graph lines when they ran Debian 7.
> > >
> > > The RRD netstat file, which is used for the statistics graph, shows a 'U'
> > > for
> > > the 'Out' and 'Retrans' values. Looking at the actual code (in
> > > xymond/rrd/do_netstat.c), it seems that the netstat output is expected to
> > > be
> > > the same for most Linux distributions and versions. It shows:
> > >
> > > =========
> > > /* This one matches all Linux systems */
> > > static char *netstat_linux_markers[] = {
> > > "packets received",
> > > "packets sent",
> > > "packet receive errors",
> > > "active connections openings",
> > > "passive connection openings",
> > > "failed connection attempts",
> > > "connection resets received",
> > > "connections established",
> > > "",
> > > "",
> > > "",
> > > "",
> > > "segments send out", /* Yes, they really do write "send" */
> > > "segments received",
> > > "",
> > > "segments retransmited",
> > > NULL
> > > };
> > > =========
> > >
> > > However, the netstat output collected by the clients shows, looking at
> > > the TCP
> > > section:
> > >
> > > =========
> > > Tcp:
> > > 3045575 active connection openings
> > > 251770 passive connection openings
> > > 9335 failed connection attempts
> > > 4520 connection resets received
> > > 37 connections established
> > > 1359715245 segments received
> > > 1330630207 segments sent out
> > > 119457 segments retransmitted
> > > 10 bad segments received
> > > 32339 resets sent
> > > InCsumErrors: 2
> > > =========
> > >
> > >
> > > Some things seem to be wrong:
> > >
> > > 1) The code looks for 'active connections openings', but netstat shows
> > > 'active
> > > connection openings'. Singular on the 'connection' word.
> > >
> > > 2) The code looks for 'segments send out', but netstat shows 'segments
> > > sent
> > > out'. So despite the comment in the code, the output uses 'sent' rather
> > > than
> > > 'send'.
> > >
> > > 3) The code looks for 'segments retransmited', but the netstat output
> > > shows
> > > 'segments retransmitted'. So there is a double 't' in retransmitted (or 3
> > > all
> > > together).
> > >
> > > 4) The order of the 'segments' lines is different from the code, but I'm
> > > not
> > > sure if that is important. (Haven't looked at the code that much in
> > > depth.)
> > >
> > >
> > > I'm not sure if this is the cause of the TCP/IP stats graph not showing
> > > values,
> > > but it doesn't seem right.
> > >
> > >
> > > Thanks,
> > >
> > > John.
> > >
> > > --
> > > John Horne | Senior Operations Analyst | Technology and Information
> > > Services
> > > University of Plymouth | Drake Circus | Plymouth | Devon | PL4 8AA | UK
> > > ________________________________
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--
John Horne | Senior Operations Analyst | Technology and Information Services
University of Plymouth | Drake Circus | Plymouth | Devon | PL4 8AA | UK
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