[techtalk] Attacks?

[Kath]

I've been getting these showing up in my snort/logcheck logs.   May 19 17:13:13 hwnet �^F/bin�F^D/shA0�\210F^G\211v^L\215V^P\215N^L\211�^K�\200�^A�\200�\177���   What are they, how are they being done and how can I prevent/block them?   - Kath