[netflow-tools] Softflowd not recognizing interface index

Jason Dixon jason at dixongroup.net
Mon May 23 13:20:04 EST 2005

On May 22, 2005, at 11:11 PM, Damien Miller wrote:

> Jason Dixon wrote:
>> I've dropped pfflowd to try out softflowd as it appears to be a bit 
>> more "compliant" than the pfflowd exports.  However, I notice that my 
>> flows still don't seem to be reporting the correct index numbers for 
>> the interfaces.  I'm not very SNMP savvy, so perhaps it's my own 
>> inexperience showing.  Can someone please explain to me why the 
>> following output all have 0 as the if_index_in and if_index_out for 
>> all flows?
>> http://www.dixongroup.net/softflowd.txt
>> A good example is seen on lines 1-2 and 8-9.  Each pair represents 
>> the same SSH session but they appear to come from different softflowd 
>> agents (first from the external interface, then the internal).  
>> Regardless, they all report an if_index_* of 0, no matter the 
>> direction or agent.
> Yes, softflowd doesn't get enough information from bpf to fill these 
> in.
> If you can figure out a way to get interface names of indices out of
> libpcap I can fix it easily.

Hell, I don't even grok the significance of the if_index_* stuff, other 
than to assume that it's somehow valuable.  I would think that the 
reporting agent would always report its own interface as 0, but what do 
I know.  :)

Unfortunately, what I know about pcap could fit into a bottlecap.

Jason Dixon
DixonGroup Consulting

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