RE: udp.sendmsg

[<webman at manfbraun dot de>]

Hello !

Many thanks for your answer!
Sometimes, writing "it's not working" reactivates some areas
in the own brain, do dig deeper ...
What ist failing for me, is my modified version of the original
script. I run the original and no errors at all ... ;-)

So, here is MY version - with my little newbies thinking about
this type of scripts ;-)

=======================
probe begin { printf("Monitoring use of port 53\n") }
probe end { printf("Stopped.\n") }

probe udp.sendmsg {
        if ( dport == 53 ) {
                task = pid2task(pid());
                printf(
                        "UDP53 %5d.%6d %15s %d(%s/%s) %d(%s)\n",
                        gettimeofday_s(),
                        gettimeofday_ms(),
                        daddr,
                        pid(),
                        task_execname(task),
                        execname(),
                        ppid(),
                        pexecname()
                        )
        }
}
============================
I came to this modified version, because I found out,
that there are some other programs attempt to get
mDNS resolution via port 5353 (not shown above).

So I made this above, to get more context information.
A hint would be great!

Thanks so far and
best regards,
Manfred


> -----Original Message-----
> From: David Smith [mailto:dsmith@redhat.com]
> Sent: Friday, August 19, 2016 6:32 PM
> To: webman@manfbraun.de; 'Frank Ch. Eigler'
> Cc: systemtap@sourceware.org
> Subject: Re: udp.sendmsg
> 
> On 08/18/2016 09:17 PM, webman@manfbraun.de wrote:
> > Hi !
> >
> > Thanks for reply - any sorry for my late answer. The mail lands
> > unexpectedly in my spam folder ...
> >
> > In the meantime I build a little better usable script.
> > But something changed my Systemtap (no idea in mind).
> > The system tap script now failing after some time,
> > but was running for weeks without any problems. The
> > error is:
> >
> > UDP53 1471300316.1471300316458  192.168.26.254 6071(iceweasel/DNS
> Res~ver
> > #60) 1(systemd)
> > ERROR: kernel string copy fault at 0x00000000000004f0 [man error::fault]
> > near identifier 'kernel_string' at
> > /usr/share/systemtap/tapset/linux/conversions.stp:18:10
> > WARNING: Number of errors: 1, skipped probes: 1
> > WARNING: /usr/bin/staprun exited with status: 1
> > Pass 5: run failed.  [man error::pass5]
> 
> Systemtap is trying to protect you here from reading a bad address and
> potentially crashing the kernel.
> 
> Can you show us your current script so we can try to help you get around
> this?
> 
> --
> David Smith
> dsmith@redhat.com
> Red Hat
> http://www.redhat.com
> 256.217.0141 (direct)
> 256.837.0057 (fax)