FW: Re: Is there a line of defense against Distributed Reflective attacks?
Rob Thomas
robt at cymru.com
Sun Jan 19 19:25:03 UTC 2003
Hi, NANOGers.
] The rest could be handled with a simple IDS (doesn't even need
] to match patterns... just count packets going to 27374 and the like)
There is no "simple IDS" for OC48+ links. :) Counters are possible,
though adding that many ACLs can be more than burdensome on certain
code and hardware releases. Don't even mention logging. :/ While
some ports are more obvious than others, there is still the question
of what is in the payload of a packet that increments a counter. It
may be quite benign, e.g. a SYN packet to port 80 from source port
27374.
At the edge some of these things are quite possible. At aggregation
and transit points, however, such suggestions don't scale.
] I keep saying ISPs would be much better off if they implement these
] filters. But not all of them agree. IMHO: less 'zombies' -> better
] service -> less support phonecalls.
I agree.
Thanks,
Rob.
--
Rob Thomas
http://www.cymru.com
ASSERT(coffee != empty);
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