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Parasitic computing


Reliable communication on the Internet is guaranteed by a standard set of protocols, used by all computers1. Here we show that these protocols can be exploited to compute with the communication infrastructure, transforming the Internet into a distributed computer in which servers unwittingly perform computation on behalf of a remote node. In this model, which we call ‘parasitic computing’, one machine forces target computers to solve a piece of a complex computational problem merely by engaging them in standard communication. Consequently, the target computers are unaware that they have performed computation for the benefit of a commanding node. As experimental evidence of the principle of parasitic computing, we harness the power of several web servers across the globe, which—unknown to them—work together to solve an NP complete problem2.

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Figure 1: Schematic diagram of our prototype parasitic computer.
Figure 2: TCP checksum.
Figure 3: Deciding satisfiability using checksum.

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We thank M. Crovella, G. W. Flake, L. Giles, S. Lawrence, D. Peenock and L. Peterson for comments on the manuscript. This work was supported by the NSF.

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Correspondence to Albert-László Barabási.

Supplementary information


1. Encoding 3-SAT problem using TCP checksum. 2. Computing with TCP. 3. Algorithm. 4. Implementations. 5. Scalability. and references.

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Barabási, AL., Freeh, V., Jeong, H. et al. Parasitic computing. Nature 412, 894–897 (2001).

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