[netflow-tools] softflowd keeps crashing

Damien Miller djm at mindrot.org
Mon Apr 13 21:04:58 EST 2009

On Mon, 13 Apr 2009, alex k wrote:

> > Are all the flows incorrectly dated, or just the ones from around the time
> > softflowd exited?
> >
> It seems to me, that the first one or two flows after the crash (softflowd
> gets started automatically) are the wrong dated ones.
> It crashed at 00:04 and was started a few seconds after that (I found a
> very fast way to do that).

Just to be clear: it is the first flows out of softflowd after a restart
and not the last couple before a crash that have invalid times? Are both
the start time and the end time incorrect?

Could you try to find the details of this flow in the softflowd debug log
and see if the times are incorrect there too? The flow start time comes from
libpcap, so it is possible that it is giving us bad data.

> >> What happened? Network error? Corrupted file? Socket problem?
> >
> > Is anything restarting (bringing down and back up) the network interface
> > on which softflowd is listening? That can cause this sort of problem.
> > This line:
> >
> >> Shutting down after pcap EOF
> >
> > Indicates that libpcap has closed itself.
> As far as I can see, the network interface had no problem at that time.
> The host is monitored and was never unreachable.
> It could have been a problem with VMware. (The IP with the wrong dated
> entries is a virtual machine.)
> How can I find out, if it's a libpcap problem? It all happens in memory,
> right?

Are you running softflowd with a pcap filter on the commandline?

You might also want to try this diff:

Index: softflowd.c
RCS file: /var/cvs/softflowd/softflowd.c,v
retrieving revision 1.98
diff -u -p -r1.98 softflowd.c
--- softflowd.c	3 Sep 2007 10:50:05 -0000	1.98
+++ softflowd.c	13 Apr 2009 11:04:10 -0000
@@ -1916,7 +1916,7 @@ main(int argc, char **argv)
 				logit(LOG_ERR, "Exiting on pcap_dispatch: %s", 
-			} else if (r == 0) {
+			} else if (r == 0 && capfile != NULL) {
 				logit(LOG_NOTICE, "Shutting down after "
 				    "pcap EOF");
 				graceful_shutdown_request = 1;

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