[Snort-users] Alerts with the incorrect Source IP (proxy server)

Bamm Visscher bamm.visscher at ...11827...
Thu Oct 25 07:56:02 EDT 2012


If he's logging the IP of the proxy and not the external website, then
it sounds like the sensor is between the internal network and the
proxy. If that is the case, enable_xff won't help since at that
location the destination IP address hasn't been resolved (the proxy
will do that).

Brad - You can move the sensor outside the proxy and then you will get
the external website IP address, but you may have to re-architect your
proxy (turn on x-forwarded-for or use a transparent proxy) to be able
to identify the internal source of the acty. Another option would be
to add another sensor and sandwich the proxy between the two sensors.

Bamm


On Wed, Oct 24, 2012 at 2:10 PM, Joel Esler <jesler at ...1935...> wrote:
> If you have additional logging turned on, and your proxy supports it, (and
> you have "enable_xff") turned on in the snort.conf we'll log the actual IP
> in the additional data in the unified2 file.
>
> --
> Joel Esler
> Senior Research Engineer, VRT
> OpenSource Community Manager
> Sourcefire
>
> On Oct 24, 2012, at 1:27 PM, Jeremy Hoel <jthoel at ...11827...> wrote:
>
> What snort alerts what the IPs are from inside the packet. If you
> tcpdump that same connection and you are seeing the proxy talk to the
> client, and that's the packets that are making the alert then the way
> to fix that is to move the span port location.  Snort only reports
> what it sees and it can't 'infer' what the original source of the
> packets are.
>
> But more examples of your network layout and an example of the alert might
> help.
>
> On Wed, Oct 24, 2012 at 5:04 PM, Turnbough, Bradley E.
> <bturnbough at ...15650...> wrote:
>
> Hi Guys,
>
>
>
> I’m getting alerts generated, but they are coming up as the source IP of my
> proxy server.  Is there a way to tell Snort / Barnyard2 / Snorby that it
> should report the IP address of the website instead?
>
>
>
> Thanks,
>
> Brad
>
>
>
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