https://github.com/gavinandresen/bitcoin-git/tree/fuzzer

It is a transaction fuzzer; adding block fuzzing is on the TODO.

Basic usage is:
1. Use the send* RPC commands to get one or more transaction IDs
2. Run a script that repeatedly calls relayfuzzed with a nonce/txid
... and see how the connected peer(s) react to all the fuzzy 'inv/tx'
protocol messages.

I built it to stress-test BIP 16, there are lots of useful features that
could be added.  Patches welcome!

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Gavin Andresen