[Bro] invoking an analayzer without the default policy script?

Mike Wood muscletot at gmail.com
Wed Dec 5 10:36:29 PST 2007


On 12/5/07, Robin Sommer <robin at icir.org> wrote:
>
> On Tue, Dec 04, 2007 at 15:43 -0800, Mike Wood wrote:
>
> > this dns_request handler does not get called unless I add
> >
> > @load dns
>
> Most likely you haven't set the capture filter to include DNS
> packets into the analysis. Try adding this to your script (which is
> from dns.bro):
>
>      redef capture_filters += {
>         ["dns"] = "port 53",
>         ["netbios-ns"] = "udp port 137",
>      };

I gave that a shot, but still didn't see any output.

I did have success by adding the following:

global dns_ports = { 53/udp, 53/tcp, 137/udp };
redef dpd_config += { [ANALYZER_DNS] = [$ports = dns_ports] };

(also from dns.bro), and that triggered my event handler for dns_request.
Note this seemed to work with and without redefining the capture filters.

Any ideas why this is the case?  Particularly, am I only going to be
able implement my custom event handlers for analyzers that are part of
the DPD framework?

Many thanks,
Mike



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