Enrico
see inline

On Sep 26, 2011, at 8:48 PM, Enrico Papi wrote:

> we are not setting any BPF filter in snort config
> consider my previous post without that snort output error.
> our problem shows up doing the following steps:
> compile the tcpdump included in the pf_ring tar with libpcap-1.1.1-pf_ring 
> support
> start sniffing with that tcpdump on an interface not pf_ring aware after 
> loading pf_ring module in trasparent mode = 1
> results: you do not see any packets
> is it normal? can you try it?

Yes, it is normal.
When PF_RING is in transparent_mode=1,2, it expects to receive packets directly 
from the NIC, and does *not* listen for packets coming from the linux stack.

> 
> you can reproduce the same problem (no packets received) using a pf_ring 
> aware snort with daq PCAP (not daq pfring) on a non pf_ring nic. 
> in both those cases libpfring should not be used as i am not sniffing on a 
> pfring nic but on a standard nic and i should see packets since i am simply 
> using tcpdump on a standard nic.
> for now i have solved in the following way:
> use snort daq pfring for all snort instances (even on the NICs not pfring 
> aware) -- is it correct? why it works ???
> use a tcpdump version compiled using libpcap-pfring library but without 
> -lpf_ring flag -- why it works ???
> 
> a further question:
> can i put pf_ring in transparent mode=2 and use pf_ring aware applications 
> also for standard NICS?

No, with vanilla drivers you have to use transparent_mode=0

Best regards
Alfredo

> for example, in the same enviroment described in the previous post, it would 
> mean using snort with daq pfring on the intel NIC and the same snort binary 
> with daq pcap on the Chelsio T4.
> accordingly to what happens now in my system i would not see the packets 
> flowing in the Chelsio......
> 
> about DNA igb driver:
> i have to say that we have done simply a test and we do not intend to use dna 
> features.
> 
> you can reproduce the problem doing:
> compile pf_ring kernel mod, compile libpfing with dna support, compile 
> libpcap-pfiring, compile tcpdump with libpcap-pfring support
> load pfring module in  trasparent_mode = 2 , no tx mode, quickmode=1
> compile and load igb 3.x DNA driver
> start sniffing with tcpdump like this #tcpdump -i dna0
> SYSTEM HANGS.....(i do not have trace file)
> the system spec are the same of the prev. post.
> 
> 
> On 09/26/2011 12:33 PM, Enrico Papi wrote:
>> 
>> Enrico
>> the libpfring library is not able to set BPF filters as they fall into the 
>> libpcap domain, not PF_RING. MY colleague Alfredo is working at a fix for it 
>> that will be out later this week, so you       won't have to wait too long.
>> 
>> Can you please let us know how to reproduce the DNA issues?
>> 
>> Regards Luca
>> 
>> 
> 
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