Wednesday, February 7, 2007

Another Attack on DNS Root Server Infrastructure

For those of you who need more information, Wikipedia has a good article on why DNS root servers are important to everybody.

Every time you type a URL, or click on a link in your web browser a DNS server directs your computer’s browser to the right server on the Internet. For performance reasons, you usually use the DNS server on your local network or one provided by your ISP. Your local DNS server relies in-turn, on other DNS servers in a tree-like hierarchy. Ultimately, all DNS servers rely on the smooth functioning of the thirteen DNS root servers.

An attack on the root servers is an attack on the fundamental structure of the Internet. It’s the DDOS equivalent of a doomsday device. This the sort of thing a villain like Ernest Blofeld would attempt; it could be the action of a sociopath, the prelude to a grand attempt at extortion, the test of an info-weapon or an act of war.

Fortunately, as noted by John Crain, this type of attack has become much harder to pull-off. However, Harder ≠ Impossible. The current infrastructure can handle an enormous load, but there are limits. The picture below shows the situation at 11:00 AM PST:

Picture 1: (2/6 17:00 UTC - 19:00 UTC)

As you can see in this reporting period, two of the thirteen servers are still experiencing significant load. The following picture shows the effect of the attack from its beginning:

Picture 2: (2/6 08:00 UTC - 2/7 08:00 UTC)

As you can see, the attack hit server ‘’G’’ and ‘’L’’ the hardest. The red spikes indicate an average probe failure rate exceeding 90%.

Most likely, this attack will not affect you directly. It is a lot like a solar flare’s effect on radio communications – there’s a lot more noise in the system today and don’t be surprised if you notice a slightly different “feel” to the Internet today.

The lesson here?

Performance monitoring is often a leading indicator to an attack on your computer infrastructure. It is important to understand your baseline performance and monitor the systems you rely on for any significant deviation from baseline.

For the Internet, we can thank the very good folks at RIPE .

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