Snort mailing list archives

Re: Snort 2.9, RHEL 5 and afpacket DAQ


From: beenph <beenph () gmail com>
Date: Wed, 20 Oct 2010 15:03:48 -0400

In daq_afpacket.c there is a #define  which people who would like to set
bigger buffer might want to take a look.

#define AF_PACKET_MAX_BUFFER_SIZE   128

<SNIP>
  for (entry = config->values; entry; entry = entry->next)
    {
      *  if (!strcmp(entry->key, "buffer_size_mb"))
            size_str = entry->value;
*        else if (!strcmp(entry->key, "debug"))
            debug = 1;
    }
    /* Fall back to the environment variable. */
    if (!size_str)
        size_str = getenv("AF_PACKET_BUFFER_SIZE");

    if (size_str && strcmp("max", size_str) != 0)
    {
        size = strtoul(size_str, NULL, 10);
        if (size > AF_PACKET_MAX_BUFFER_SIZE)
       *     size = AF_PACKET_MAX_BUFFER_SIZE;
*    }
*   ** else
        size = AF_PACKET_MAX_BUFFER_SIZE;
*
    /* The size is specified in megabytes. */
    size = size * 1024 * 1024;

</SNIP>
On Wed, Oct 20, 2010 at 2:19 PM, Mike Lococo <mikelococo () gmail com> wrote:

On 10/20/2010 01:35 PM, Eoin Miller wrote:
afpacket is nearly identical to mmap'd libpcap. Just give afpacket a
bigger buffer and the performace should be extremely comprable, and you
don't have to use super old libpcap anymore.

I think what Ralf is asserting, and Rich and confirming, is that buffer
sizes larger than ~50MB are failing with afpacket (but not with the
Woods patches)... so it is not (yet) possible to use a comparable buffer
size for some unknown reason.

Cheers,
Mike Lococo


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------------------------------------------------------------------------------
Nokia and AT&T present the 2010 Calling All Innovators-North America contest
Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store 
http://p.sf.net/sfu/nokia-dev2dev
_______________________________________________
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