Re: Excluding the bulk of UDP from IPS processing - What's the impact?

[Joel Jaeggli <joelja () bogus com>]

Jamie Riden wrote:
> 2009/8/26 Bikram Gupta <bikramkgupta () gmail com>:
> > Scenario: Perimeter IPS deployment, with Stateful firewall at the egress point.
> >
> > Traffic from out to in: Firewall will block all unsolicited UDP ports.
> > For the UDP ports where traffic is allowed (RTP data etc) through
> > firewall, do I have to pass it though IPS engine? Will there be cases
> > of exploits in such cases? Some examples please.

sip is a big source of udp ips rules.

> > Traffic from in to out: I believe IPS processing for UDP flows must be
> > enabled here.. to detect some of the p2p, IM, skype, trojan etc
> > traffic.
> >
> > I am trying to understand the impact, if I bypass the UDP flows from
> > IPS device? Can this be done realistically for some UDP traffic
> > (in->out, out->in), or NONE?
> >
> > Thanks a lot.
> >
> > Bikram
>
> Slammer was UDP. Witty was UDP.
> http://en.wikipedia.org/wiki/SQL_slammer_(computer_worm)
> http://en.wikipedia.org/wiki/Witty_(computer_worm)
>
> RTP is complex enough that I wouldn't be surprised at a few parser
> bugs popping up at some point.
>
> I'd rather get a higher-powered IPS than not looking at UDP, but it
> depends on your cost/benefit analysis.
>
> cheers,
>  Jamie

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