Growing DoS attacks

Tom Sands tsands at
Thu Jan 17 13:43:50 UTC 2002

    The DDOS attacks we see are generally a mixture.  I couldn't care less about the
ICMP (which are frequent) since we already rate-limit that, and protect against Smurf
attacks as well.  UDP and SYN floods are harder to try and prevent or rate-limit with
our type of customer base.  The destination of our DDOS attacks vary greatly,
normally we don't see the IRC servers as the overwhelming majority.

    Spammers, shell hosts, our equipment, and even just normal web sties (that others
may not like) are all equal targets of DDOS attacks.  Granted there are always the
repeat offenders.

    Most of the details I have been able to see from DDOS attacks are just logs of
Source/Destination IP and packet type, not an actual packet capture to be able to
examine the packet.  I would be interested in knowing what article you read also.

Avleen Vig wrote:

> On Wed, 16 Jan 2002, Paul Froutan wrote:
> > Hello all,
> > Can some of you with larger networks let me know about the volume of the
> > DoS attacks you have experienced lately?  Our experience has been that the
> > volume (not just occurrence) is going up significantly and I'm curious on
> > the size of attacks that people are experiencing.  For reference, while a
> > year or two ago we used to get 50-100 meg attacks, now we're getting 500+ megs.
> I don't run a large network, but I am curious and will help where
> possible.
> Are you able to say what kind of DoD attacks are taking place?
> ICMP Floods? TCP Floods? UDP Floods? A mixture?
> If you feel the src addr is spoofed, have you taken a packet capture and
> looked for similarities in the packets?
> I read a paper about 5 months ago where someone had worked very hard at
> analysing the differences in packets generated by various DoS agents.
> Maybe you should attempt to trace them back?
> If they are Smurf attacks, I may be able to help more, let me know.
> --
> Avleen Vig
> Network Security Officer
> Smurf Amplifier Finding Executive:

Tom Sands
Chief Network Engineer
RackSpace Managed Hosting
tsands at

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