[Xymon] Debian 9 stretch clients - trends netstat graph bug? - patch attached
John Horne
john.horne at plymouth.ac.uk
Thu Mar 21 12:57:16 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.
>
Hi,
I would have agreed, but as far as I can tell the code looks for a specific
order for the data when a regex is used. This is fine for *BSD/UNIX, but is not
valid for Linux. So it cannot use a regex (without changing yet more code).
I thought about defining a new OS type other than 'LINUX' and 'LINUX22', but
felt that the type may well be used in other parts of Xymon. So adding a new
Linux type may cause problems elsewhere.
In the end I made a relatively simple change to just one file (do_netstat.c).
For Linux systems it checks the netstat output for one of the typo strings. If
it is found, then it uses the current code. If it is not found, then it uses
the new set of strings to check the netstat output. (Basically the new set is
the same as the old one, but with the typos corrected.)
I checked the net-tools source and it seems that all the typos affecting Xymon
were fixed in one commit. So checking for just one typo in the code should work
fine.
Patch file attached.
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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This email and any files with it are confidential and intended solely for the use of the recipient to whom it is addressed. If you are not the intended recipient then copying, distribution or other use of the information contained is strictly prohibited and you should not rely on it. If you have received this email in error please let the sender know immediately and delete it from your system(s). Internet emails are not necessarily secure. While we take every care, University of Plymouth accepts no responsibility for viruses and it is your responsibility to scan emails and their attachments. University of Plymouth does not accept responsibility for any changes made after it was sent. Nothing in this email or its attachments constitutes an order for goods or services unless accompanied by an official order form.
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