http://www.eicar.org/86-0-Intended-use.html
It's detected by almost any antivirus product, on my work computer the corporate antivirus immediately quarantines a file with this content.
X 5 O ! P % @ A P [ 4 \ P Z X 5 (...)
>Just for fun, there's about 8000 reachable nodes on the network at the time of writing. Assuming that a large portion of the network is unreachable (NAT, filtering, intermittent, just not listening), it's probably safe to assume there's probably at least 50,000 nodes with the complete blockchain. If we XOR just the chainstate, we cause 50000 * 430 MB of disk writes, 50000 * 430 * 2 MB read and write combined, somewhere in the region of 43TB. If we XOR the entire blockchain on disk we cause 50000 * 21000 * 2 MB of IO, around 1.95PB of RW across the wider Bitcoin network. Incredible.
It's possible I misunderstand, and overestimate the value of full nodes.
Anyway - what does being a full node entail?
It takes a few hours to a half day for the node to catch up, depending on your bandwidth and CPU, but after that it requires relatively little processing time. But you do need ~20 GB of free hard drive space for the blockchain.