[ovs-discuss] [PATCH] secchan: Avoid sending NetFlow packets for empty flows.

Ben Pfaff blp at nicira.com
Fri Aug 28 22:43:02 UTC 2009


This particular change should only affect netflow.

I know that you mentioned the many used:never flows earlier in
IM.  Did you ever file a bug report on that?  It sounds like
something that we should try to understand, although it may or
may not be actually a bug.

<reid at nicira.com> writes:

> Silly question,
> Does this have the side-effect of glossing over port-scan-like activity?  I
> know my dpctl dump-flows has had dozens of thousands of flows that have
> used:'never', due to hpinging, but perhaps that was related to recently
> resolved bugs.
>
>   -Reid
>
> On Fri, 28 Aug 2009 15:08:00 -0700, Peter Balland <peter at nicira.com> wrote:
>> Seems like a perfectly reasonable check to me.
>> 
>> Peter
>> 
>> Ben Pfaff wrote:
>>> There is no value in sending out NetFlow messages when the byte counter
>>> (hence, packet counter) is 0.  This does not often happen, but it can in
>>> corner cases where a flow gets installed but never sees any traffic
>> before
>>> it is uninstalled.
>>>
>>> CC: Peter Balland <peter at nicira.com>
>>> ---
>>>  secchan/ofproto.c |    2 +-
>>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/secchan/ofproto.c b/secchan/ofproto.c
>>> index efa5c9b..b3fef1b 100644
>>> --- a/secchan/ofproto.c
>>> +++ b/secchan/ofproto.c
>>> @@ -1696,7 +1696,7 @@ rule_post_uninstall(struct ofproto *ofproto,
>> struct rule *rule)
>>>      struct rule *super = rule->super;
>>>
>>>      rule_account(ofproto, rule, 0);
>>> -    if (ofproto->netflow) {
>>> +    if (ofproto->netflow && rule->byte_count) {
>>>          struct ofexpired expired;
>>>          expired.flow = rule->cr.flow;
>>>          expired.packet_count = rule->packet_count;
>> 
>> 
>> _______________________________________________
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