North American Network Operators Group

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Re: DDoS attacks, spoofed source addresses and adjusted TTLs

  • From: Mike Tancsa
  • Date: Wed Aug 03 17:12:43 2005

At 04:55 PM 03/08/2005, Christopher L. Morrow wrote:
> hops away, the TTL of the packet when it got to me was 56).  Yes, I know
> those could be adjusted in theory to mask multiple sources, but in practice
> has anyone seen that ?

what exactly was the question?
You answered it mostly-- what do people see in the real world-- plain jane unadulterated packets, or spoofed / manipulated ones. Of all the attacks I have suffered through, they all seemed to be from legit IP addresses save one and that was some time ago. However, except for 2 people in about 4 years, I have never gotten a response from various NOC/Abuse desks as to whether or not the attacking IPs I identified were in fact part of the attack or were spoofed.

However, in the cases where I had customer PCs participating in attacks, there seems to be a higher percentage of random source addresses (which get dropped before they leave my network). Have that many networks implemented RPF as to make spoofed addresses moot ?

---Mike